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By A. M. Gaudin

IT is only in recent years that substantial progress has been made in developing a physico-chemical picture of the solid state. The molecular concept, so useful in dealing with gases, was naturally carried over to the field of crystalline solids; it has resulted in the firm implanting of erroneous concepts that only now are being eradicated successfully. Two simply written and effective books on the subject are Crystal Chemistry by Stillwell1 and An Introduction to Crystal Chemistry by Evans.' A more complete treatment of the subject is available in a book by Wells.' The monograph by Hückel4 also touches on a subject most easily perceived by reference to the brief introduction by Bragg,5 that master of the field. These texts make it clear that while some solids are built of molecules, many are built of ions, others of atoms connected in the form of giant molecules, and still others of cations and electrons. The various lattices in which these entities are systematically arranged, the joint use of several of these entities, and the transitional character of some of the bonds make for the great variety of crystalline solids. The purpose of this paper is to point out a most important corollary of present views on the structure of solids. In this connection the classification of solids in Table I is helpful. Atomic crystals are those formed by the noble gases, e.g., helium and argon. They are soft, sublime at very low temperature, of very low specific gravities, and not encountered in ores. Molecular crystals are uncommon among inorganic materials, common among organic materials. Typical examples from both inorganic and organic fields are sulphur, iodine, naphthalene, benzene, and carbon tetrachloride. These crystals are soft and have low specific gravities; where the molecules are small, the sublimation temperature is low. Filament and sheet crystals are rare. They are typified by elemental selenium and elemental arsenic, respectively. Graphite and molybdenite come near being sheet crystals. These crystals are soft in some directions, tough in others, sublime at various temperatures. Diamantine crystals, typified by diamond, are very few in number, stable at high temperatures, and extremely hard. Ionic crystals are common. Most salts, acids, and alkalies belong in the two classes of ionic crystals; examples are rock salt, fluorite, calcite, and angle-site. The salts, acids, and alkalies that do not belong in these classes are more properly regarded as transitional between ionic crystals, framework crystals, and diamantine crystals, e.g., ice and quartz. Fiber crystals are relatively uncommon mineral-ogically speaking, but common in the fields of living processes. Examples are asbestos, silk, cellulose, and wool. Many fiber crystals are so little known even now that their crystallinity may be doubted. Layer crystals, among the more interesting and useful of solids, include a wide variety of substances

Jan 1, 1956

By W. D. Robertson, H. Conrad

Incremental loading creep tests were conducted on magnesium single crystals in tension and direct shear at 78" to 364°K. The creep curves were transient in character and exhibited waves or periodic behavior, especially at small strain rates. A sigmoidal curve was frequently observed following the first occurrence of creep. Repeating of segments of a master curve was observed at all temperatures indicating that identical conditions for flow existed after various stress and strain histories. A logarithmic time law with a independent of temperature whs observed at 78°and 203°K, while a parabolic (power) time law was approximated at 298" and 364°K. The departure from logarithmic creep was attributed. to recovery, which was observed at 298" and 364°K. The temperature independence of a represents a serious objection to the theory of low-temperature creep based on the intersection of dislocations. IN a previous paper1 it was found that the initial creep rate of magnesium single crystals, y, following the addition of a stress increment in the range of 78° to 364°K, was given by the expression ? = C exp - {?H/kT} exp {B(T- h ?)} [1] where B and C are constants, AH is an activation energy of 10,300 cal per mole, T is the applied stress, ? is the total strain at the time of the stress increment, and h is the strain-hardening coefficient. The present paper is concerned with certain other features of creep behavior observed during this investigation; namely, the form of the creep curves, time laws for creep, recovery, and microscopic and X-ray observations of the structural manifestations of the creep flow. To the authors' knowledge the temperature range of the present investigation (0.08 Tm to 0.40 Tm) has not been covered previ-

Jan 1, 1959

Using 5-p Ni powder and 0.018 ,u A1203, oxide dispersion strengthened nickel alloys were prepared by mechanical mixing of powders, followed by compaction, sintering and extrusion. Processing variables such as cooling of the powder during mixing, electrostatic discharging, mixing time, amount of oxide, and so forth, were studied to determine the effects on room-temperature tensile and high-temperature creep-rupture properties and on the reproducibility of alloys. MECHANICAL mixing of metal and metal oxide powders provides one of the simplest and most inexpensive methods for preparing dispersion strengthened metal-metal oxide alloys;" however, because of large differences in specific gravity, powder particle diameters and other variables, difficulties have been encountered in reproducing alloys and alloy properties. Using 5-p Ni powder and 0.018 p A1203, the following variables were investigated: a) Blending techniques b) Blending time c) Volume fraction of oxide for the selected pow- ders d) Sintering of compacts before extrusion Cooling of Powders During Blending— Cremens and Grant had indicated that dry ball milling of the powder mixture gave superior results over other procedures. When ultra-fine metal and oxide powders became available and comminution was unnecessary or offered little gain, the use of dry mixing in a Waring Blendor gave optimum results.' In the current study, observations of the powder mixtures indicated that considerable heat was generated due to the high speed of the Waring Blendor (15,000 rpm). This heating appeared to produce some degree of clustering and pelletizing. To minimize such agglomeration, a Pyrex cooling coil was installed in the mixing vessel. A double coil, water cooled, proved to be quite satisfactory, providing a fair degree of cooling along with good erosion resistance. Discharge of Electrostatic Charge—Electron-microscopy showed that agglomeration was minimized by the cooling procedure but was not entirely eliminated. It appeared that some of the ag- glomeration had to be explained on the basis of an electrostatic attraction due to the high-speed blending operation. These charges had the effect of promoting the growth of alumina clusters. At the end of the blending procedure such clusters had an effective size which was as much as 50 times that of the individual powder particles and were very tightly bunched. Several methods were utilized to try to discharge the electrostatic forces to minimize the clustering. One successful method, utilized in alloy 17, involved continuous exposure during blending to a radium source of 50 millicuries at a distance of 1.5 ft from the container. A number of other methods were noted to work equally well. Fig. 1 shows the more open oxide structure which results from such a treatment, permitting the matrix metal to penetrate into the cluster more effectively. The combination of powder cooling and discharging led to noticeably improved structures. Fig. 2 shows a cross and a longitudinal section in alloy M-17, one of the best alloys, illustrating the marked decrease

Jan 1, 1961

By H. R. Ogden, E. S. Bartlett, A. G. Imgram

Notched and unnotched tensile specimens of wrought and recrystallized, oxygmted and hydro-genated tantalum and columbium were tested over a range of temperatures selected to encompass the ductile-to-brittle transition. Increasing the oxygen content of tantalum and columbium increased their strength, and raised their ductility transition temperature, but did not cause a marked deterioration of notch properties below that of commercially pure material. The adverse effects of oxygen were more pronounced for recrystallized structures than for wrought material. The effects of hydrogen are complicated by strain aging or slow strain rate hydrogen embrittlement at -105°F. However, in general, hydrogen had only a minor effect an strength, but markedly increased the effective transition tem-terature and caused a deterioration of notch properties . BCC metals including the refractory metals in Groups Va and VIa (V, Cb, Ta and Cr, Mo, W) can be expected to undergo a ductile-to-brittle transition and exhibit brittle fractures at low temperatures.' Notch embrittlement is associated with this phenomenon, and can be a serious design problem. Table I compares the tensile transition behavior and notch sensitivity of commercially pure Group Va and VIa refractory metals. The Group VIa refractory metals have considerably higher transition temperatures, and become notch sensitive at higher temperatures, than do the Group Va refractory metals. In addition, the Group VIa refractory metals are sensitive to metallurgical structure. Recrystallized structures generally have higher transition temperatures than wrought material of the same composition. The relatively poor transition behavior of the recrystallized structures of these metals is generally attributed to the segregation of interstitial impurity atoms at grain boundaries. Pronounced sensitivity to structure is not evident with commercially pure Group Va refractory metals, however. Since these metals have higher solubilities for interstitial elements than do the Group VIa metals ,4 it can be expected that higher total interstitial concentrations are necessary to develop a comparable degree of grain boundary segregation and to produce a similar sensitivity of transition temperature to structure. Increasing only the concentration of interstitial atoms in solution would tend to increase the flow stress of a metal in relation to its cleavage fracture stress and thereby raise its transition temperature, but would not be expected to cause a marked sensitivity of transition temperature to structure. A research program has been conducted at the Battelle Memorial Institute to evaluate the effects of interstitial oxygen and hydrogen on the transition behavior and notch sensitivity of tantalum and columbium, and to evaluate the effects of structure on "contaminated" material. EXPERIMENTAL PROCEDURES Notched and unnotched tensile specimens of oxygenated and hydrogenated tantalum and columbium with both wrought and recrystallized structures were tested over a range of temperatures selected to encompass the ductile-to-brittle transition Oxygen levels selected for study in both tantalum and columbium were nominally 500 and 1000 ppm, whereas nominal hydrogen contents were 150 and 500 ppm in tantalum and 150 and 300 ppm in columbium. Oxygen and hydrogen additions were made directly to 6-in. lengths of 1/2-in.-diam electron beam melted wrought bar stock, in a Sieverts Apparatus. Subsequent high-temperature annealing was required for homogenization of the oxygenated material, but was not necessary in the case of hydrogenated stock. The oxygenated and hydrogenated bars were then swaged to 1/4-in.-diam rods. Tensile specimen blanks were cut from the 1/4-in.-diam rods and annealed to achieve stress-re-

Jan 1, 1963

By J. C. Fisher

Martensite transformations in steels and other alloys are characterized in part by the absence of composition changes during the growth of a new phase. Transformation occurs rapidly, and there is insufficient time for long range diffusion or partition of alloying elements to take place; martensite reactions in alloys thus are similar to phase transformations in single component systems. A fundamental understanding of martensite transformations in steels is impossible without knowledge of the free energy change upon transforming austenite (face centered cubic iron containing alloying elements) to ferrite (body centered cubic iron containing alloying elements) of the same chemical composition. The present paper assembles the best information available concerning the influence of temperature and composition on this free energy change. Most of the material has been taken from the work of Johansson,' Mehl and Wells,2 Zener3,4 and Smith;5 and indirectly, through these authors, from the work of Austin.6 In agreement with the generally accepted viewpoint, martensite is assumed to be an ordered solution of carbon in ferrite of the same composition as the parent austenite; only at high temperatures and low carbon concentrations is the carbon in ferrite distributed at random. The properties of the disordered solution are estimated by extrapolating the known properties of iron-carbon solid solutions into the range of supersaturation, and the free energy change associated with ordering is estimated from the theory developed by Zener. By incorporating Smith's recent thermodynamic measurements and Zener's theory of ordering, the present analysis modifies previous estimates of the free energy change associ- ated with martensite transformations. Consider a two component system consisting of a solvent A and a solute B. Let Na and Nb represent mol fractions of A and B respectively, let aa = raNa and ab = YbNb represent activities, and let superscripts 1 and 2 refer to phases 1 and 2. The partial molal free energies of A and B in phases 1 and 2 can be summarized as follows: free energy standard state Fa' - Fao1 = RT In an1 pure A' Fa2 - Fa2 = RT In aa2 pure A2 Fb1 - Fbo = RT In ab1 pure B Fs2 - FB2 = RT In aB2 pure B. The free energy of a gram atom of phase 1 is* AF1 = Na'Fa1 + Nb'Fb1 and that of phase 2 is AF2 = NA2FA2 + NB2Fb2. A martensite transformation from phase 1 to phase 2 requires Na1 = Na2 = Na and NB1 = NB2 = Nb, and the free energy change per gram atom accompanying transformation is AFi-2 = NA(Fa2 - Fa1) + Nb(Fb2 - Fb1) = NA[RT In (aA2/aA1) + AFa1?2] + Nb RT In (aB2/aB1) = Na[RT In (ra2/ra1) + AFa1?2] + Nb RT In (TaVTB1). [1] where yn2, yn1, yB2, yB1 are activity coefficients, and where Ma'+* is the free energy change upon transforming a gram atom of pure A from phase 1 to phase 2 at the temperature in question. For martensite transformations in plain carbon steels, A = iron (Fe), B = carbon (C), 1 = austenite (7). 2 = ferrite (a), and Eq 1 is AFr ?a= NFe[RT In (rf.a/rfer) + AFF.r?a] + TVc RT In (eca/rc1)- L2] Nothing is known concerning the values of yFea and yca for carbon concen- , trations in excess of 0.025 pct. However, the approximation rf.7 = 7f." = 1 cannot be appreciably in error for small carbon concentrations, and Eq 2 reduces to Afr-a = NfeFfer?a1 + NC RT In (rca/rcr)- [3] Johanssonl and Zenera have calculated MFfr?a from the specific heat measurements compiled by Austin.6* Their calculated values agree closely, and are summarized in Table 1. The activity coefficients relative to graphite for carbon dissolved in iron vary with temperature according to the relationships d In rcr/d(1/T) = AHcr-R dlnyca/d(l/T) = AHCa/R where AHc? and AHca are the heats of solution of graphite in y and a iron. Assuming the values of AH to be independent of carbon concentration and temperature, In rCr = AHcr/RT + I1 In rca = AHCa/RT + 12

Jan 1, 1950

By AIME AIME

OPPORTUNITY may not be knocking but it, at least, is waiting for you, your family and your friends in that amazing republic south of the Rio Grande. For the first time we are able to publish the official itinerary for the forth-coming Mexico City meeting of 1936. As shown on Page 351, the deluxe special train leaves St. Louis on Thursday. Nov. 5 at 5:30 p.m., returning to St. Louis on Nov. 18 at 8:15 a. m. The schedule provides seven days and six nights in Mexico City with numerous excursions to nearby towns and resorts. The oldest surviving city in' North America is Mexico City, dating back at least to the twelfth century. It was the Aztec capital when Cortez arrived in 1519. The famous cathedral still standing was built on a foundation of sculptured Indian images and the remains of a great Aztec temple. Today it is a city of romance.

Jan 1, 1936

By Corliss R. Kinney

SINCE the first atomic bomb exploded over Japan, a great deal of speculation has been published about the use of atomic energy instead of coal for the production of power. Atomic energy, in time, may displace coal for this purpose, but atomic energy will not displace coal in supplying chemical raw materials to the rapidly expanding carbon-chemicals market. Modern civilization demands large quantities of carbon compounds and the logical source of many of these is coal. Consequently, many progressive operators are considering the possibilities of the utilization of coal as a chemical raw material as never before. Furthermore, the demand for clean, smokeless, and ashless fuels will continue to increase and the only way to handle coal under those conditions is to take it apart, just as crude petroleum is taken apart. One can readily imagine where the petroleum industry would be now if it had insisted on selling customers only crude oil, perhaps emulsified with a little salt water to correspond to the moisture and mineral matter in raw coal. The time seems to be coming at an accelerated pace when mine operators will find that competing for a highly selective fuel market by producing a larger tonnage at smaller cost will be less profitable than to increase the value of a smaller tonnage many fold by producing something more valuable to industry and civilization than raw coal. For example, about 750,000 tons of carbon black selling for $50 to $60 per ton was produced in the United States in 1945. This tonnage is insignificant compared with the total production of coal in the United States, but a very tidy tonnage, together with the coal necessary to operate the process, for any mine operator fortunate enough to obtain a method of producing a better carbon black from coal. From the point of view of tonnage, the manufacture of coke of various kinds and its by-products is at present the most important source of carbon chemicals from coal. Nearly 20 per cent of the coal mined in this country is used for this purpose. A large proportion of the coke is used for the production of iron and steel, but even in this operation a considerable part of the coke is used for a chemical purpose; that is, the reduction of the ore to metallic iron. In addition, large quantities of coke are used in manufacturing many important products that find their way into the market. POSSIBILITIES OF ACETYLENE One of the important chemicals manufactured from coke is calcium carbide, from which many products are made. One of these is acetylene. This hydrocarbon can also be manufactured from natural gas or from waste oil-refinery gas and' these industries will probably offer competition for the manufacture of acetylene. Coke-oven gas can be used for making acetylene and should receive consideration

Jan 1, 1946

By H. C. George

At the annual meeting of the Institute in February, 1927, we had a comprehensive discussion of Petroleum Engineering Education. This discussion covered basic training and prerequisites, laboratories and equipment, graduate courses, availability of lecturers, geological engineering, petroleum production engineering, refinery engineering, transportation engineering and economics and management. However, there are several phases of petroleum engineering education, which many members of the Institute felt should be further discussed at this year's meeting. The first was expressed by me in a letter to those participating in the written discussion, from which I quote as follows: "We fell that the question of handling engineering graduates who enter the petroleum industry should be thoroughly discussed. "During the first five years after graduntion from college, how can these young men be best trained to be of the greatest service to the industry and at the same time do work which will be interesting and of a character which will make them feel that they are accomplishing something and making progress leading toward personal advancement?" Both the written and oral discussion would indicate three groups of opinion; first, those who advocate letting the young engineers go into the industry and take care of themselves without any supervision, direction, or guidance; second, those who advocate the taking of young engineers into the industry and letting them go through all the steps that any laborer or any other mian without a technical education would take, but with some supervision, and third, those who advocate that young cngineers should be given special training for several years after entering the industry. Of course all of these different groups are found in rnost of our industries. The Doherty training school of the Empire Gas & Fuel Co., finds its counterpart in the practice of the Gcneral Electric and Westing-house companies in the electrical industry and the Baldwin and Brooks Locomotive works in mechanical engineering.

Jan 1, 1928

By Marie L. V. Gayler

Without diffusion taking place in liquid metals and alloys, no castings could be made; it is therefore the most important factor affecting the structure of metals. Diffusion involves the interchange of atoms, a process which takes place during the life history of an ingot. In the liquid, atoms are in a state of high thermal agitation, but this thermal vibration is reduced in amplitude with falling temperature. When solidification sets in, the atoms arrange themselves on an ordered space lattice and the changes in structure which take place in the solid are due to the interchange of atoms on this space lattice. The rate of atomic interchange—e.g., of diffusion—is most rapid at temperatures close to the melting point and decelerates as the temperature is lowered. At room temperature, the rate of diffusion is practically negligible in most alloys, and any change in structure can only be brought about by using methods which will accelerate the rate of diffusion. The rate of diffusion depends on three factors (I) temperature; (2) concentration gradient and (3) activation energy. The growth of grains and particles in the solid alloy also depend on these factors and are therefore intimately associated with diffusion. The rate of homogenization in a cast alloy depends on several factors, such as: (I) rate of solidification, which involves grain and particle size which, in their turn, depend on diffusion: (2) the nature of the constituents; (3) the temperature interval between the melting point of the metal or alloy and the temperature at which it is being heat-treated. It is well known that coarse, cast structures are extremely difficult—if possible— to homogenize, and the finer the grain size and particle size, the more readily solid solution will take place. The rate of diffusion depends, also, largely on the nature of the constituents; for instance, copper and magnesium form solid solutions with aluminum quite readily but nickel and iron do not; neither do certain intermetallic compounds, such as alpha and beta FeSi. Furthermore, the actual formation of intermetallic compounds may be a very slow process, particularly when they are formed in the solid state as equilibrium products. For example, BFeSi is formed in the solid as the result of the reaction aFeSi + A1 —+ PFeSi. The particles of aFeSi become surrounded with a reaction ring of PFeSi. This layer is formed as the result of diffusion of atoms taking place between the aluminum matrix and aFeSi. As the amount of aFeSi surrounding the core of aFeSi increases the concentration gradient becomes low and so the rate of diffusion of atoms also decreases until it practically ceases. This occurs after a comparatively thin layer of ßFeSi has been formed. It follows that when intermetallic compounds of this type are formed in the solid, as the result of diffusion, it is generally impossible ever to attain equilibrium, since the forma-

Jan 1, 1944

By Marie L. V. Gayler

Without diffusion taking place in liquid metals and alloys, no castings could be made; it is therefore the most important factor affecting the structure of metals. Diffusion involves the interchange of atoms, a process which takes place during the life history of an ingot. In the liquid, atoms are in a state of high thermal agitation, but this thermal vibration is reduced in amplitude with falling temperature. When solidification sets in, the atoms arrange themselves on an ordered space lattice and the changes in structure which take place in the solid are due to the interchange of atoms on this space lattice. The rate of atomic interchange—e.g., of diffusion—is most rapid at temperatures close to the melting point and decelerates as the temperature is lowered. At room temperature, the rate of diffusion is practically negligible in most alloys, and any change in structure can only be brought about by using methods which will accelerate the rate of diffusion. The rate of diffusion depends on three factors (I) temperature; (2) concentration gradient and (3) activation energy. The growth of grains and particles in the solid alloy also depend on these factors and are therefore intimately associated with diffusion. The rate of homogenization in a cast alloy depends on several factors, such as: (I) rate of solidification, which involves grain and particle size which, in their turn, depend on diffusion: (2) the nature of the constituents; (3) the temperature interval between the melting point of the metal or alloy and the temperature at which it is being heat-treated. It is well known that coarse, cast structures are extremely difficult—if possible— to homogenize, and the finer the grain size and particle size, the more readily solid solution will take place. The rate of diffusion depends, also, largely on the nature of the constituents; for instance, copper and magnesium form solid solutions with aluminum quite readily but nickel and iron do not; neither do certain intermetallic compounds, such as alpha and beta FeSi. Furthermore, the actual formation of intermetallic compounds may be a very slow process, particularly when they are formed in the solid state as equilibrium products. For example, BFeSi is formed in the solid as the result of the reaction aFeSi + A1 —+ PFeSi. The particles of aFeSi become surrounded with a reaction ring of PFeSi. This layer is formed as the result of diffusion of atoms taking place between the aluminum matrix and aFeSi. As the amount of aFeSi surrounding the core of aFeSi increases the concentration gradient becomes low and so the rate of diffusion of atoms also decreases until it practically ceases. This occurs after a comparatively thin layer of ßFeSi has been formed. It follows that when intermetallic compounds of this type are formed in the solid, as the result of diffusion, it is generally impossible ever to attain equilibrium, since the forma-

Jan 1, 1944

By B. F. Buie

For over 200 years meerschaum has been a significant item of trade between the Near East and countries to the west. Best-known for its use in making smoking pipes and cigar and cigarette holders, it is also used in making a variety of decorative and ornamental items. It is easily carved, and is given an attractive, lustrous finish by rubbing. No published specifications are known, but compact form, purity, uniform whiteness or light color, and uniform, porous texture appear to be requisites. Fig. I a shows the appearance of a piece of crude meerschaum from Turkey; Fig. lb a carved item; and Fig. lc, d, and e show the fibrous and porous texture as revealed by the scanning electron microscope. Neither a major industrial mineral nor a precious stone, meerschaum nevertheless holds a record of long-and continuing-association with art and personal affairs of man. It is also a mineral to which modem methods of exploration and production probably could be profitably applied. An interesting account of the preparation and use of meerschaum in the early part of this century is given by Sterrett (1907). Geology and Mining Mineralogy Meerschaum is recognized now to be the compact variety of sepiolite, the claylike variety of which is one of the minerals included in the chapter on clays. The word meerschaum, from the German meaning "sea foam," was in earlier times used synonymously with sepiolite, a word of Greek origin suggestive of the resemblance of the compact variety-then the only variety known-to cuttlefish bone. At one time meerschaum was used as the commercial name, and sepiolite for the scientific name. However, to think of meerschaum as the name by which sepiolite is known commercially is no longer valid, in view of the recent emergence of the earthy variety as a competitor of bentonite and other clay materials. Present tendency is to restrict the term meerschaum to the compact variety, and to use the term sepiolite as a more general name to include both the compact and earthy varieties. This is the terminology followed in this publication. Meerschaum typically is white to light gray, has a hardness of 2 to 2 ½ , conchoidal to irregular fracture, and specific gravity varying with porosity from about 2 to less than 1. The composition is somewhat variable,- but is near that determined by Schaller (1936) for sepiolite as 2MgO.3SiO2.4H2O. A more modern for mula based on X-ray determination of the crystal structure is given by Caillére and Henin (1961) as (Site) (Mg9)030(OH)6(0H2)46H20. The reason for the firm, compact nature of meerschaum, in contrast with the earthy variety of sepiolite, is not fully understood. It may be due to the presence of a very minor amount of some bonding material such as silica. Scanning electron microscope (SEM) photographs of a specimen from Turkey (Figs. lc-le) indicate that the meerschaum is composed predominantly, if not entirely, of crystalline fibers which merge into sheetlike forms in a complex, intertwined mass. Detailed X-ray and crystal structure data, as well as some data on thermal stability range, are given by Caillère and Hénin (1961) for the sepiolite family of minerals. Mode of Occurrence and Origin Most authors have attributed the origin of meerschaum to alteration of serpentine or other magnesian minerals. The occurrence in alluvium and other surficial deposits does not necessarily indicate that the alteration was supergene. In fact, hydrothermal origin appears more likely for some deposits, though not for all.

Jan 1, 1983

ASIDE from the John ,Fritz Medal, in which the Institute participates through its representation on the John Fritz Medal Board, the Institute itself has four awards it may make annually, as follows : the Robert W. Hunt Medal and Prize, the J. E. Johnson, Jr., Award, the James Douglas Medal, and the William Lawrence Saunders Medal. ROBERT W. HUNT MEDAL AND PRIZE The partners of Robert W. Hunt established a fund which was presented to the Institute at a fitting ceremony on May 27, 1920, to establish an annual medal and a sum of money to be awarded under the following rules: 1. The award shall consist of two prizes: first of a gold medal, second of a sum of money; a certificate to accompany each prize. The money prize shall not be awarded to a member over 40 years of age, but under unusual circum- stances, both prizes may be allotted to one person provided that he is not over 10 years of age. In general it will be understood that the Committee shall award the money prize to the younger men, rather than the medal. 2. The awards shall be made not oftener than once a year to that person or persons contributing to the Institute the best original paper or papers on iron and steel. The scope of the term "iron and steel" shall be determined by the sub-committee considering the awards. In general, papers dealing with the practical side of the subject have preference over those dealing with the theoretical side in recognition of the fact that Captain Hunt's main' contributions to the industry have been in the improvement of production and quality of material. 3. A sub-committee of three to five, including the Chairman of the Iron and Steel Committee, shall be appointed by the Iron and Steel Committee annually to adjudge the award subject to approval. 4. The awarding committee shall submit its report to the Iron and Steel Committee at its October meeting, and the award shall be certified to the Secretary of the Institute in time to permit the presentation to be made at the Annual Meeting of the Institute. 5. The recipient of the award shall be designated "The Hunt Medallist." This prize is administered by the Iron and Steel Committee. Awards of the medal have been made as follows: 1920-Robert Woolston Hunt. 1926-Charles Lewis Kinney, Jr. J. E. JOHNSON, JR., AWARD This award is made from the income of a fund of $3000 donated by Mrs. Margaret Hilles Johnson in memory of her husband, J. E. Johnson, Jr., who was a prominent engineer, author of two valuable volumes on iron blast-furnace construction and practice, vice-

Jan 1, 1928

By John M. Hancock

IN beginning my remarks, may I make it entirely clear that since January 4, 1947, I have not been a member of the United States Delegation to-the United Nations Atomic Energy Commission I am speaking, therefore, in purely a personal capacity. Because of the interest of the engineering profession with reference to uranium, and because of the title assigned me for this talk, I am going to assume that you know what the United States Plan is for the control of atomic energy. At best, in the limited time, I could only summarize, at the risk of giving undue emphasis to the items mentioned, and at the risk of omitting many important parts of what seems so far to be a complete and well-rounded Plan for meeting the problem. I will aim to comment upon those aspects of the Plan that continue as problems and involve apparent, or obvious, misunderstandings and contrary views The control of atomic energy represents not only a problem but a challenge-both faced by- all the peoples of the world It involves a new approach to the problems of the kinds that arise between nations, problems that have not ever been solved even by international treaties in their efforts to outlaw weapons of war. These efforts range from the Kellogg-Briand treaty to outlaw war, and its obvious failure to prevent World War II, to the interdiction by the Pope of the use of the crossbow in the days of the Crusades. All previous plans have been failures-that makes

Jan 1, 1947

With only one certain exception coal was never used by the Indians, before white men came to America, for any purpose except as an ornament or for paint. Within the past few years it has been discovered that the Hopi Indians in Navajo County, Arizona, used lignite for burning pottery, about 1000 A. D., as dated by tree rings. They were able to obtain a clear color in their ware that could not be obtained with brushwood fires. The coal was mined by hammers from outcrop openings, some of which can still be seen, and the tools used have been found in them.1 (See also p. 376.) Small figurines made of splint or cannel coal have been found at various localities in western New York, in Ohio and possibly other places, evidently made for ornaments. There is no reason to think they are of any greater age, if as old, as that mentioned above. Some crushed coal was used by the Indians as a black pigment in painting themselves, but apparently the eastern Indians never used coal for any other purposes. Some think that several tribes of Indians in the Northwest, along the Missouri, used coal as fuel, the basis being a statement attributed to Radisson about 1660. In the Jesuit Relations of 1659-1660 it was stated that Radisson anti Groseilliers had just returned from a visit to Lake Superior and beyond. "In the country of the Poualak, which means 'warriors' they say `as wood is scanty in supply and small in size in their country, nature has taught them to make fire with coal from the earth (charbon de terre) and to cover their cabins with skins.'"2 This statement was only hearsay with the good fathers, and the reputation for veracity of the two explorers is not of the best, and it is extremely probable that instead of coal they used turf, dry grass or buffalo chips. In fact in Radisson's Voyages' he does not mention coal at all in his account of the third voyage, when he was supposed to have seen it used. His accounts of his travels are badly mixed, and he and his companions were much better travellers than narrators. None of the early travellers up the Missouri River saw any evidence even then that the Indians were familiar with the use of coal. In the writer's opinion it is unlikely that coal was used as stated by the Jesuits.

Jan 1, 1942

By E. R. Russell, N. E. Richards

The current ejyiciency of aluminum cells was derived from the metal produced over a period of time and the theoretical faradaic yield. The difference in the actual amount of aluminum in the cathode at the beginning and end of the period must be determined. The weight of aluminum in the cathode was calculated from the dilution of an added quantity of impurity metal. Use of multiple indicator metals, copper, manganese, and titanium, demonstrated that the weight of aluminum in cells can be determined to within 1 pct with routine but careful chemical analyses. Over intervals of the order of 30 days, current efficiencies reliable to within 1 pct can be obtained. INVESTIGATIONS beginning with those of Pearson and waddington ,' through the most recent published work of Georgievskii,9-11 illustrate the direct relationship between the composition of the anode gas and the applicability of analysis of anode gases to the control of alumina reduction cells. McMinn12 noted the lack of an independent method for measuring cell production efficiency over the short term. There is no doubt that changes in the current efficiency are immediately reflected in the composition of anode gases. However, the accuracy of faradaic yields calculated from gas analyses depends upon the degree of interaction between primary anode gas and Carbon.6 A conventional industrial practice of obtaining long-term current efficiency for production units from mass balances and quantity of electricity is generally insensitive to the impact of planned control of any one or more of the influential reduction cell parameters such as temperature, alumina concentration, and mean interelectrode distance. Consequently, there is a real need in the aluminum industry for a procedure to obtain the absolute cell current efficiency over a short term—10 to 30 days—both for the calibration of values obtained from gas analysis6 and for evaluating the effect of controlling specific parameters in the reduction process. The amount of aluminum produced may be determined by considering the cathode pool as a reduction of an impurity metal in aluminum. Analyses over a period will show a decreasing concentration of the impurity due to the accumulation of aluminum solvent. The increase in aluminum inferred from analyses is the amount produced by the cell during the period. Combining weights of the cell aluminum in the cathode at the beginning and end of a specific period, weights of aluminum tapped and the quantity of electricity passed during the interval will yield the current efficiency. Smart,I3 Lange;4 Rempel,15 Beletskii and Mashovets,16 and winkhaus17 have used dilution techniques to determine aluminum inventory in alumina reduction cells. A technique for determining the weight of aluminum in production cells by addition of small amounts of copper to the aluminum cathode was described by smart.13 The precision in values of the aluminum reservoir through dilution of copper in the cathode ranged from about 1 to 3 pct depending upon the quantity of copper added in the range 0.2 to 0.01 wt pct, respectively. Because the method appears so direct and apparently simple, one would not anticipate difficulties in application to industrial cells. The objective of this study was to resolve this problem associated with the trace metal dilution technique for determining the amount of aluminum in a cell. The approach in evaluating trace metal dilution as a basic factor in determining the weight of aluminum in the cell reservoir, and the absolute current efficiency of the Hall-Heroult cell, was to dilute more than one trace metal in the aluminum cathode so that we could discriminate among complications arising from physical mixing, the possibility of separation of intermetallic compounds, loss of the added elements, and chemical detection. EXPERIMENTAL METHODS These experiments are not complex but require standardized procedures. The technique involves addition of the trace metals to the cathode, knowing when these metals are homogeneously distributed in the liquid cathode, timing of the sampling, employing accurate and precise analytical methods, using reliable procedures for monitoring the amount of electricity passed through the cell, and accurate weighing of aluminum removed from the cell during the particular period. More accurate results might be obtained if the increment in concentration of the added indicator metals were of the order of 0.1 to 0.2 wt pct. The method must be applicable to production units and, hence, the contamination of the aluminum minimized. For this reason, the concentration of trace metals in the cathode was kept below 0.07 wt pct and generally at 0.04 wt pct level. Trace quantities of copper, manganese, titanium, and silicon are already present in virgin aluminum and are suitable as additives from electrochemical and analytical points of view. Concentration of silicon is quite dependent upon the characteristics of the raw materials and was not used extensively in this work. Chemical Analyses. All instrumental analyses require calibration against an absolute technique such as a gravimetric, volumetric, or spectrophotometric method which represents the ultimate in sensitivity, precision, and accuracy. On review, the best methods for copper appeared to be optical absorption without

Jan 1, 1969

By M. A. Mayers, J. A. Thompson

In recent years, the problem of damage to coke-oven walls by expanding coal charges undergoing carbonization has engaged great attention on the part of research workers in this field, and has led to the development of many devices for estimating these pressures.l-14 Only in Russell's method" and in the Koppers ovens7 are conditions quite similar to those in commercial ovens. Tests even in these ovens are empirical because no information has been published to permit an evaluation of "scale effects." Owing to the relatively large wall area in these test ovens, the average wall pressure determined may be lower than that existing in localized areas. This factor may be compensated for in part by the testing of coal charged into the test oven at a bulk density that is as high as the highest that is believed to exist in commercial ovens. Both of these lacks might be filled by the development of an adequate gauge for the direct measurement of wall pressure exerted by the charge in commercial coke ovens in normal operation. Previous attempts to elaborate such instruments7,15 have resulted in units which, because they had to be water-cooled, probably produced changes in the conditions of carbonization, and which had to be removed from the oven before carbonization was complete, to avoid their destruction. Late in 1941 the Coal Research Laboratory undertook to develop such a gauge, in which gas pressure was balanced against the charge pressure and which thus would not require water cooling, on a suggestion made in 1937 by one of the present authors and William B. Warren, a former member of the Laboratory staff. The gauge heads themselves were to be simple and cheap enough so that they might be discarded after each run if seriously damaged. This would permit them to be left in place throughout the carbonizing period, when they could be pushed out with the coke. The basis of the design, of which the latest exemplification is shown in Fig. I, was that as the internal gas pressure within a flexible metal envelope was increased, the flexible wall would move away from a stop when the gas pressure just overbalanced the charge pressure. If the stop were an insulated electrical contact, the point of balance could be indicated by the breaking of an electric circuit. It was anticipated that, while the instrument must operate at high temperature, the presence of a strongly reducing atmosphere throughout the carbonizing period would so reduce the danger of scaling that mild steel could be used for the gauge. This expectation has been justified. Danger of attack on silica oven walls by the steel gauge body can be eliminated by cementing asbestos paper or an alundum or silica plate to the back of the gauge body. The gauge head itself has a relatively heavy mild-steel body, A, into which standard ¼-in. pipe B is screwed to conduct gas and electrical leads. The body is closed by a single bellows C, consisting of two annuli of 0.011-in. (o.a8-mm.) cold-rolled shim-steel spot-welded together at their outside edges. The lower one is

Jan 1, 1944

By J. A. Thompson, M. A. Mayers

In recent years, the problem of damage to coke-oven walls by expanding coal charges undergoing carbonization has engaged great attention on the part of research workers in this field, and has led to the development of many devices for estimating these pressures.l-14 Only in Russell's method" and in the Koppers ovens7 are conditions quite similar to those in commercial ovens. Tests even in these ovens are empirical because no information has been published to permit an evaluation of "scale effects." Owing to the relatively large wall area in these test ovens, the average wall pressure determined may be lower than that existing in localized areas. This factor may be compensated for in part by the testing of coal charged into the test oven at a bulk density that is as high as the highest that is believed to exist in commercial ovens. Both of these lacks might be filled by the development of an adequate gauge for the direct measurement of wall pressure exerted by the charge in commercial coke ovens in normal operation. Previous attempts to elaborate such instruments7,15 have resulted in units which, because they had to be water-cooled, probably produced changes in the conditions of carbonization, and which had to be removed from the oven before carbonization was complete, to avoid their destruction. Late in 1941 the Coal Research Laboratory undertook to develop such a gauge, in which gas pressure was balanced against the charge pressure and which thus would not require water cooling, on a suggestion made in 1937 by one of the present authors and William B. Warren, a former member of the Laboratory staff. The gauge heads themselves were to be simple and cheap enough so that they might be discarded after each run if seriously damaged. This would permit them to be left in place throughout the carbonizing period, when they could be pushed out with the coke. The basis of the design, of which the latest exemplification is shown in Fig. I, was that as the internal gas pressure within a flexible metal envelope was increased, the flexible wall would move away from a stop when the gas pressure just overbalanced the charge pressure. If the stop were an insulated electrical contact, the point of balance could be indicated by the breaking of an electric circuit. It was anticipated that, while the instrument must operate at high temperature, the presence of a strongly reducing atmosphere throughout the carbonizing period would so reduce the danger of scaling that mild steel could be used for the gauge. This expectation has been justified. Danger of attack on silica oven walls by the steel gauge body can be eliminated by cementing asbestos paper or an alundum or silica plate to the back of the gauge body. The gauge head itself has a relatively heavy mild-steel body, A, into which standard ¼-in. pipe B is screwed to conduct gas and electrical leads. The body is closed by a single bellows C, consisting of two annuli of 0.011-in. (o.a8-mm.) cold-rolled shim-steel spot-welded together at their outside edges. The lower one is

Jan 1, 1944

WALTER N. CRAFTS,* Toronto, Canada (written discussion?).-During the forging of 9.2-in. shells -for the United States Army, it was noticed that better results were obtained in certain instances when test bars had been held sometime before pulling. An investigation, therefore, was made by our metallographer, Mr. F. M. Arnold, to determine the effect of seasoning. The forging consists of a single operation, piercing a solid cast blank. The test sections were cut from the walls by an oxyacetylene flame, one piece from the nose end and one from the base on the opposite side. The test pieces were not heat treated in any way and the tests and seasonings were carried on at normal atmospheric temperatures. The specifica-tions were as follows: Standard 2-in. test bar, 0.505 in. in diameter; elastic limit, over 19 long tons, or 42,500 lb.; ultimate stress, 39.6 to 49.1 long tons, or 87,500 to 110,000 lb. per sq. in.; elongation, over 13 per cent. As a preliminary test two heats were selected; BP555, which was tested and reported failed on elongation on Aug. 20; and B01771, which was tested and reported failed on Aug. 24. On Aug. 29, retests were cut and machined from the same shells and held till Sept. 3 (5 days) when they were pulled. Both sets of results are given below.

Jan 12, 1919

By C. B. Post, G. V. Luerssen

It is generally recognized that non-metallic inclusions in steel come from two principal sources. First are the chemical reactions in the furnace, or in subsequent deoxidation, resulting in slag which does not free itself from the metal. Much information has been published concerning these chemical reactions and their control through proper attention to slag viscosity, composition of deoxidizers, and other qualities. The studies of this subject by C. H. Herty, Jr. and others through the medium of physical chemistry have yielded much information for the steelmaker. The second source is erosion of ladle refractories, such as lining brick, stoppers, nozzles and runners, causing entrapped particles of globules of fluxed silicate material. In contrast with the large amount of information available on the first source, relatively little has been published on the subject of erosion which, in the case of basic electric melted steel, is the principal source of nonmetallics. This is probably due to the fact that the problem was assumed to be one of simple mechanical erosion, which could be solved primarily by modification of ladle practices. Good improvements have been made by elimination of slurries in the ladle, better ladle and runner refractories, and more attention to pouring temperatures. It is doubtful, however, that this problem has been recognized in its true light since it is not one of simple mechanical erosion but rather one of chemical reaction between the metal and the refractories; and in this sense is as much a problem of physical chemistry as the reactions involved in the actual steelmaking process. The influence of ladle refractories on the resulting cleanness of steels was early recognized by A. McCancel who examined large inclusions in steels made by both acid and basic practices. His chemical analyses showed the large influence exerted by the manganese content of the steel on erosion of the ladle and nozzles used in those days. The presence of MnO in such inclusions led McCance to the hypothesis that both basic and acid steels react chemically with the ladle refractories so that small globules of fluxed refractories are carried in the stream into the molds. This early work of McCance was checked by one of the present authors on basic electric bearing-steel, and it was found that on steels containing as low as 0.40 pct manganese the fluxed surface of the ladle lining after delivering such a heat showed as high as 25 pct MnO by actual analysis. Furthermore, by lowering the manganese content of the steel to 0.20 pct, ladle erosion was decreased with a corresponding decrease in silicate inclusions in the steel. Limitations placed on the manganese content for the required inherent properties made it impossible to pursue this line further, and subsequent attention was concentrated on improved ladle refractories, care in keeping the ladle clean and free from loose refractories up to the time of tapping, and pouring the steel at optimum temperature. Our study of the chemical reactions at the metal-brick interface between steel and ladle refractories was revived in 1939 as a result of an experimental observation made on the cleanness of alloy steels of the SAE types. This observation showed that the relative cleanness of such steels made in basic electric arc furnaces of 12 ton capacity and poured in ingots ranging from 1100 to 2200 lb weight was determined to a large extent by the ratio of the manganese and silicon contents, provided other steelmaking variables such as tapping temperature, pouring temperature, pouring time, amount of aluminum added for grain size control, and degree of deoxidation in the furnace were kept reasonably constant. Detailed studies made on the deoxidation and slag practice during the refining period of basic electric furnace practice showed that these two variables exerted some influence on the resulting cleanness of steel in the form of bars and forgings. The important variable, the manganese-silicon balance, was not apparent until heats were made in succession by the best furnace practice kept under fairly rigid metallurgical control. Another observation pertinent to this work concerned the similarity in the microscope of slag particles causing magnaflux or step-down indications in subsequent rolled bars, and the patches of slag frequently seen on the surface of ingots. These patches are generally believed to come from the glassy metal-brick interface in the ladle and represent an entrapment of such glass (both from the ladle brick and nozzle) in the metal as it flows over the refractories in the neighborhood of the nozzle. These glassy particles are carried down into the mold with the liquid steel, and gradually coalesce into a slag "button" which floats on the surface of the steel as it rises in the molds. Periodically the button is washed to the side of the ingot where it is trapped between the surface of the ingot and the mold, later appearing as a slag patch on the surface of the ingot after stripping. Even though most of the small glassy particles coalesce into a slag button while the ingot is being poured, it is logical to suspect this step in the steelmaking process as being a source of slag lines large enough to cause trouble

Jan 1, 1950

By L. Valentik

Many attempts have been made during the last 40 years to evaluate the performance of gravity separation equipement, that is, the effectiveness with which light and heavy particles are separated. The most comprehensive treatment of the subject was made by Cerchar at the 1st International Conference on Coal Preparation held in Paris in 1950. The methods suggested by the Conference were accepted and very widely used in the last two decades. This paper discusses an improved method of evaluation in the light of the now-accepted standard presentation. The float-and-sink analysis of the product is presented on a Gaussian distribution curve, resulting in an easier visualization of the inherent difficulties of separation. The ogives of the distribution curve me then plotted, giving a quantitative measure of the deviation from perfect separation as an error distance instead of an error area. Illustrations of the new method are given both for gravel and for coal preparation, but the content is valid and applicable to other types of minerals which are separated by gravity methods. Many attempts had been made during the last forty years to evaluate the performance of heavy-media separation (HMS) equipment, that is, the effectiveness with which floats and sinks are separated.'-' The most comprehensive treatment of the subject was made by Cerchar at the 1st International Conference on Coal Preparation held in Paris. 6 The primary aim was the thorough understanding of the mechanism of separation and the unified presentation of data on gravity separation so that the evaluation and comparison of washery performance could be made from all over the world. No strict overall standardization has been achieved, but after the conference a more or less uniform presentation of performance was accepted, which, during the last two decades, has been very widely used. In this paper, illustration of the old methods and an improved method of evaluation will be given. HEAVY-MEDIA SEPARATION (HMS) PERFORMANCE CRITERIA In the ideal HMS process, all material lower in density than the specific gravity of separation (SGS) would be recovered as floats and all material of higher density would appear as sinks. In order to evaluate the misplaced material, the washery products are tested at the density at which the washing unit is operated. The original type of plot1,7, 8 is shown in Fig 1; this was developed primarily for coal cleaning units. The curve for raw coal represents the cumulative percentages of sink material. The refuse curve is also plotted as a cumulative sink, the percentages being expressed in terms of raw coal. This diagrammatic representation of the results of washing units has the merit of easy visual observance of the degree of separation obtained. The error areas (cross-hatched) are a measure of the amount of misplaced material and therefore they can be used to characterize the quality of separation. The ideal and actual separating performance between floats and sinks can be best seen from the partition curve developed by Tromp,2 where the ordinate is the percentage recovery of the sinks, and the abscissa is the specific gravity (Fig. 2). It can be seen from the shape of the curve that as the SGS is approached, the proportion of material reporting to the improper product increases rapidly. In fact, the SGS can be defined as the density of the material in the feed that is distributed equally between float-and-sink products. When the upper half of the curve is inverted, a shape similar to that of a Gaussian error distribution curve is obtained and therefore the analysis of gravity separation may be carried out by using the law of probability. The shape of the curve in Fig. 2 is determined partly by the density composition of the feed, and partly by the sharpness with which the unit separates floats from the sinks.9, l0

Jan 1, 1970