Search Documents

By G. R. Kotler, W. A. Tiller, W. C. Johnston

Experiments carried out on 100 g samples of molten tin and Sn-Pb alloys showed that the magnitude of the field strength, H, does not effect the supercooling, aTn, at which the initial nucleus of solid forms. However, the nuwlber of nuclei forming per cc, n, is found to increase greatly with H for fixed ATN and to increase with ATN for fixed H. The value of n increases greatly with the presence of solute and is found to he indefiendent of the cooling rate of the simples. Further, the most effective time for stirring to enhance n is immediately following the initiation of recalescence. The effect of inducing nucleation with the aid of a mechanical impact both in the presence and absence of stirring has also been studied. All proposed mechanisms for the enhancement of n by physical means seem to be inadequate in accounting for these results. IN any real nucleation experiment there are two effects influencing the results that would not be predieted from classical homogeneous nucleation theory. These may be separated into chemical and mechanical effects. The chemical effects are twofold. 1) Nucleation catalysts are present which enhance the nucleation frequency of new grains over that predicted by classical homogeneous nucleation theory.' 2) Solute will restrain the growth of nuclei so that many others may form.2,3 The mechanical effects are also two-fold. 1) Vibration (sonic or ultrasonic) of the freezing liquid enhances the nucleation frequency of new grains over that given by the chemical effects alone.4-6 2) Macroscopic fluid-flow effects produce the same effect as l).'7' It is also possible to influence the nucleation experiment by certain physical effects such as the application of electric and magnetic fields.9 From classical homogeneous nucleation theory one would predict the following relationship between the nucleation rate, N1 (number of nuclei formed per unit volume per unit time), and bath supercooling, AT, for an isothermal experiment.

Jan 1, 1963

By J. T. Crawford

ALTHOUGH nearly 10 pct of the total tonnage of coal produced annually within the United States is handled by bulk freighters on the Great Lakes, very little of the detail connected with it has been published other than occasional newspaper stories and publication of tonnage statistics. Of the total tonnage floated on the Lakes each year some 10,000,000 is stored and distributed from the port of Duluth Superior, at the western end of Lake Superior commonly known as the Head of the Lakes. This port has the largest single area concentration of coal docks in the world. Since this area contains the largest ore docks, the largest movable material handling bridge, the largest and highest grain elevator and the largest coal briquetting plant in the world, it is entirely fitting and proper that here also should be located the largest coal dock and what we believe to be the worlds largest clam shell. Of the sixteen coal docks operated by ten companies, five are owned and operated by the North Western-Hanna Fuel Co. which has two docks on the Superior, Wis. water-front and three docks in Duluth, Minn. It is with these five docks that we are primarily concerned. GENERAL HISTORY In the summer of 1871 a small sailing vessel entered the harbor of Duluth Superior with the first commercial coal cargo. All the coal brought up that first year did not amount to more than 3000 tons. During the year 1877 the first dock equipped for handling coal was built in Duluth. Coal receipts increased to 52,785 tons in 1879 the first year for which an official record was kept. Since then the volume of water-borne coal to the Head of the Lakes steadily increased to a maximum of 12,688,321 tons in the year 1923. This tonnage was nearly equalled in the year 1927 and the next highest tonnage recent year was in 1946 when 10,105,703 tons were unloaded. The average annual bring-up over a ten year period 1938 to 1947 was 8,605,231 tons. Approximately 30 pct of the coal unloaded at the Head of the Lakes is handled over the docks of the North Western-Hanna Fuel Co. Competition of other fuels coupled with expansion of coal fields in the mid-west have held coal receipts for Duluth-Superior at a relatively constant figure during the last eight years although the total tonnage of coal floated on the Great Lakes has more than doubled in the past 25 years. From the shovel and wheelbarrow method of unloading early cargoes to the horsepowered windlass derrick with a wooden tub was but a short step. The first movable coal handling, steam operated,

Jan 1, 1948

By R. E. Reed-Hill, J. L. Martin

Kinking is an important deformation phenomenon in poly crystalline a zirconium. The crjlstallo-gvaphic features of the most important form of kinking have been determined with the aid of twins formed at 77°K in grains previously kinked at high temperatures. It has been .found that the kink-band boundaries correspond to walls of edge dislocations with (1150) Burgers vectors and dislocation lines parallel to (1070). The present observations imply that basal slip is an important secondary-slip mode in polycrystalline zirconium. Previous single-crystal studies13 did not veveal this mode Other evidelzc.e for (0002)(1120) slip is also presented. ThE first studies of kinking in hexagonal metals were made by orowan,1 using single-crystal cadmium wires. He suggested that this was a new de- formation mode in metals, different from ordinary glide or twinning. Next, Hess and Barrett2 studied zinc-crystal rods in compression, and were able to offer an explanation of the phenomenon described by Orowan. They concluded that kinks required no new deformation mechanism and were a special form of deformation band that developed gradually and solely from basal glide. Similar kink bands were then observed by Washburn and parker3 on zinc crystals deformed in tension at low stresses and high temperatures. In titaniun,4 kink bands associated with {1010}<1120> prism slip have been observed in coarse-grained specimens. Magnesium5 and rhenium6 have also been observed to kink in conjunction with their basal- and {1010} prism-slip systems, respectively. Yttrium has (1010) as a predominant slip plane, but no observations of kink bands were reported.7 Since no previous investigations of kink bands in zirconium have apparently been made, this study was proposed. Its aim was to determine the crys-tallographic features of a type of kink band frequently observed in polycrystalline zirconium. EXPERIMENTAL APPARATUS All tests were performed on a type TTC Instron machine. The cross-head speed usually chosen in tension or compression was 0.02 in. per min. Ten-

Jan 1, 1964

By Earl Oliver

SEVERAL notable papers, and free discussion on many controversial subjects, marked the various sessions of the Petroleum Division at the annual meeting. The Division first convened on Tuesday afternoon, Feb. 16, and wound up with a dinner and technical meeting on Thursday night. H. C. Fowler presided at the opening session, which was devoted to problems of engineering research and production engineering. Joseph Chalmers abstracted his paper on the flow of air and gas through porous media, in the preparation of which E. L Rawlins and D. B. Talia-ferro contributed. G. H. Fancher told how much he and his associates at Pennsylvania State College were interested in this field, and described the problems they had met in conducting test work. He made a plea for standardization of testing methods. Mr. Fowler then read an abstract of written discussion by Professor Barb, which was followed by discussion by Dr. Fancher and Mr. Chalmers of technical points in connection with the Chalmers&apos; paper. H. H. Hill abstracted written discussion from Messrs. Wilde and Moore, of the Humble company. The second paper, by K. B. Nowels, on computing pressure drop in the pipe of flowing oil wells, was abstracted by the author. Messrs. Blair Smith, G. W. Coggeshall, and I. I. Gardescu participated in the discussion, and the chairman abstracted written discussion prepared by Mr. Rawlins. Most of this had to do with the viscosity of gas¬oil mixtures, on which subject Mr. Nowels said there was great need of accurate technical information.

Jan 1, 1932

In many lines of engineering, much excellent standardization work had been done before the war but the war emphasized its importance and showed most clearly the need of cooperation to prevent the confusion caused by the promulgation of overlapping standards by independent bodies. The American Institute of Mining and Metallurgical Engineers, American Institute of Electrical Engineers, American Society of Civil Engineers, American Society of Mechanical Engineers, and American Society for Testing Materials, recognizing the value of what had been done, invited the Government Departments of War, Navy and Commerce to appoint representatives to act with them to continue this work; the body so formed is the American Engineering Standards Committee. It has required time to definitely formulate its objects and to arrange methods for accomplishing them that would be effective without interfering with the many organizations that have been doing such excellent work in this line. The American Engineering Standards Committee has just completed and adopted a revision of its Constitution, which has been sent to the Governing Boards of all the Departments and Societies represented on the Committee with a request for its ratification. The new Constitution changes the name to American Engineering Standards Association as more fittingly indicating the wide scope of the interests involved. The objects of the association are stated as follows: 1. To unify and simplify the methods. of arriving at engineering standards, to secure cooperation between various organizations and to prevent duplication of standardization work. 2. To promulgate rules for the development and adoption of standards, 3. To receive and pass upon recommendations for standards submitted as provided in the Rules of Procedure, but not to initiate, define, or develop the details of any particular standard. 4. To act as a means of intercommunication between organizations and individuals interested in the problems of standardization. 5. To give an international status to approved American engineering standards. 6. To cooperate with similar organizations in other countries and to promote international standardization.

Jan 7, 1919

Discussion of the paper of A. P. WATT, presented at the St. Louis meeting, October, 1917, and printed in Bulletin No. 130, October, 1917, pp. 1476 to 1563. THE CHAIRMAN (0. M. _BILHARZ, Miami, Okla.).-Mr. Watt&apos;s reference to sorting or hand-picking of the ore in the lead district, which is being introduced at Mine La Motte, is especially interesting. I believe, from my former experience in the district, that hand-picking should be practised to some extent by all the companies in the Lead Belt. I know that a great many thousand tons containing only very small amounts of lead are passed through the mills, which, of course, is not to the advantage of milling machinery. That procedure may be Warranted at times of high prices, but I think that hand-picking should ordinarily be adopted to some extent: ERNEST GAYFORD, Salt Lake City, Utah.-On page 1525, speaking of the settling of slime previous to treatment either on slime tables or by flotation, Mr. Watt states: "The settling area allowed per ton of dry slime varies from 11 to 16 sq. ft.-an average for the district would be about 13 sq. ft. of settling area per ton of dry slime. This figure applies when the, discharge contains 20 per cent. solids." Mr. Ramsey, of the Dorr company, is here and I would like to ask him whether a settling area of 13 sq. ft. per ton of dry slime per 24 hr. is not considerably above the average area of Dorr settling tanks, and whether 20 per cent. solids is not above the general dilution for that&apos; capacity? I should also like to know what is the general average on slimes of that character. E. R. RAMSEY, Denver, Colo.-An allowance of 13 sq. ft. per ton does seem rather large. I am not familiar with the settling characteristics of the dolomitic gangue, but as an average over the country, I should say that 6 or 7 sq. ft. would be nearer correct for discharge at that consistency. L. A. DELANO, Bowie Terre, Mo.-We have had an opportunity to try our tanks at the highest capacity, and-find that by thickening the slime to 30 per cent. solids we average 12 sq. ft. per ton of dry slime. ERNEST GAYFORD.-DO you find any definite ratio between the thickness of the discharge and the settling capacity of the tank? Do you consider that the tank has a larger capacity if the discharge is 3 to 1 than if it is 50 per cent. solids? L. A. DELANO.-I think it has greater capacity with the thinner discharge. It depends a good deal on the density of feed to the tanks; in our case the feed contains 2.5 per cent. solids.

Jan 1, 1918

By E. E. Barker

ALTHOUGH flotation was known to be a successful process prior to 1912, Utah Copper Co.&apos;s ores were not entirely treated by this process until 1923. Experiments had been conducted, of course, prior to that time, and in February, 1917, the first unit of the Arthur plant was changed over from gravity concentration to flotation. On May 16, 1918, the entire Arthur plant was on flotation, excepting the coarse concentrate which was tabled prior to fine grinding. The reasons for the delay in adopting flotation at these plants were, first, that it was decided to await the outcome of the litigation with the Butte & Superior Mining Co., which began with an injunction served on Oct. 3, 1911. This litigation continued for years. Then the demands on the plants in the war years 1916, 1917 and 1918, really precluded any further drastic changes during that period, as all efforts were bent on maximum tonnage, and the cry of tonnage, rather than of recovery, was the major issue. The postwar depression followed these years of intensive production, so that it was not until 1922 that the Magna plant was equipped to use this process. Excepting, then, the amount of coarse concentrate that was tabled, 1923 was the first year when the Utah Copper Co.&apos;s ores were on, a full flotation basis. EFFECT OF FLOTATION ON ORE RESERVES The object of this paper is to point out the effect that flotation has had on the operations of the Utah Copper Co. In 1905, when D. C. Sackling began making history in copper, the ore reserves were 34,000,000 tons, with a grade of 2 per cent. copper and a mill capacity of 700 tons daily. The point of cut-off between nonprofitable and profitable grades was 1.2 per cent. A few years later the capacity was increased to 6000 tons, when 1.1 per cent became the point of cut-off. Ore reserves had climbed to 80,000,000 tons, having a grade of 1.9 per cent. In 1911 there was an ore reserve of 300,000,000 tons, with a grade of 1.5 per cent and a cut-off of 1 per cent.; in 1918 the ore reserve was approximately 400,000,000 tons, and a grade of 1.38 per cent., and point of cut-off 0.95 per cent., based on normal costs and prices. Up to this

Jan 1, 1928

By R. M. Brick

The etched mierostructures of cold-worked alpha brasses, after reductions in excess of about 20 per cent, exhibit dark lines or markings, which have been termed "deformation bands," "etch bands," and "strain markings." The terms will be used synonymously in this report. The markings are similar in their general appearance to etch figures found in cold-worked iron, aluminum and other cubic metals but in certain respects may differ noticeably. At reductions of from about 20 to 50 per cent in brass, they appear as straight dark lines of irregular spacing and at random directions in different grains, but apparently intimately associated with definite crystallographic planes, usually {ill), in each crystal. At higher reductions, the markings on the rolling plane tend to appear in a direction transverse to the rolling direction in all crystals but may bend away at considerable angles, particularly near grain boundaries. Samans,1 on the basis of X-ray and micrographic studies of two single crystals of brass, rolled to a 50 per cent reduction, showed that the lines of deformation were the edges of thin mechanical twins parallel to octahedral planes. Barrett and Levenson2-4 have made comprehensive studies of the deformation of iron and of aluminum. They show that in these two metals the deformation markings originate by division of the original homogeneous crystal into banded areas differing in orientation by an amount that increases with the degree of deformation. The markings thus cannot be twin bands, and Barrett, in a review of this subject,2 attributed Samans&apos; results on brass to an accidental choice of deformation that left the bands in approximately a twinned relationship. On the other hand, Mathewson6 has suggested that in some cases mechanical twinning offers a better rationalization of the coverage of some (111) pole figures of worked brass than the assumption of band rotation into symmetry positions. Considering next a deformed and annealed alpha brass, the most striking aspect of its microstructure is the multiplicity of twin bands.

Jan 1, 1940

By R. M. Brick

The etched mierostructures of cold-worked alpha brasses, after reductions in excess of about 20 per cent, exhibit dark lines or markings, which have been termed "deformation bands," "etch bands," and "strain markings." The terms will be used synonymously in this report. The markings are similar in their general appearance to etch figures found in cold-worked iron, aluminum and other cubic metals but in certain respects may differ noticeably. At reductions of from about 20 to 50 per cent in brass, they appear as straight dark lines of irregular spacing and at random directions in different grains, but apparently intimately associated with definite crystallographic planes, usually {ill), in each crystal. At higher reductions, the markings on the rolling plane tend to appear in a direction transverse to the rolling direction in all crystals but may bend away at considerable angles, particularly near grain boundaries. Samans,1 on the basis of X-ray and micrographic studies of two single crystals of brass, rolled to a 50 per cent reduction, showed that the lines of deformation were the edges of thin mechanical twins parallel to octahedral planes. Barrett and Levenson2-4 have made comprehensive studies of the deformation of iron and of aluminum. They show that in these two metals the deformation markings originate by division of the original homogeneous crystal into banded areas differing in orientation by an amount that increases with the degree of deformation. The markings thus cannot be twin bands, and Barrett, in a review of this subject,2 attributed Samans&apos; results on brass to an accidental choice of deformation that left the bands in approximately a twinned relationship. On the other hand, Mathewson6 has suggested that in some cases mechanical twinning offers a better rationalization of the coverage of some (111) pole figures of worked brass than the assumption of band rotation into symmetry positions. Considering next a deformed and annealed alpha brass, the most striking aspect of its microstructure is the multiplicity of twin bands.

Jan 1, 1940

By Kenneth Cottingham

The year 1941 brought a considerable increase in drilling activity in Ohio. In 1940, the total of wells completed was 1228, whereas in 1941 it was 1561, or an increase of approximately 27 per cent. Of the 1561 wells, 333 were oil wells, 701 gas wells and 527 dry holes. The completions for the past five years are shown in Table I; the number of productive oil or gas wells for the year 1941, arranged by producing formations, are given in Table 2; the number of wells, oil, gas or dry, completed in each county in 1941, in Table 3, and wells by sands in Table 4. The production of oil increased by about 500,000 bbl. in 1941, nearly all of the increase being in Pennsylvania grade. In 1940, the total production was 3,052,000 bbl. from 25,500 wells. In 1941 the total production was 3,547,534 bbl. from 24,801 wells. The increase in production is chiefly due to the Clinton pool in Clayton township, Perry County, which is briefly men- tioned later in this review. The number of oil wells, by grades of oil, and the total quantities produced are shown in Table ;. Annual oil production for five years is listed in Table 6. The average prices paid for crude in 1941 were slightly higher than in 1940 These 1941 prices, with dates of change, are shown in Table 7. The maximum production of natural gas in Ohio was in the year 1915, when the total was just under 80 billion cu. ft. The maximum consumption occurred in the year 1916, and was approximately 169 billion cu. ft. For the past several years, Ohio has ranged from eighth to eleventh, in order of gas production for the different states, being in tenth place in 1940. In the matter of consumption, however, Ohio remains in fifth place. Preliminary figures for 1940 indicate that production of natural gas increased II per

Jan 1, 1942

By Kenneth Cottingham

The year 1941 brought a considerable increase in drilling activity in Ohio. In 1940, the total of wells completed was 1228, whereas in 1941 it was 1561, or an increase of approximately 27 per cent. Of the 1561 wells, 333 were oil wells, 701 gas wells and 527 dry holes. The completions for the past five years are shown in Table I; the number of productive oil or gas wells for the year 1941, arranged by producing formations, are given in Table 2; the number of wells, oil, gas or dry, completed in each county in 1941, in Table 3, and wells by sands in Table 4. The production of oil increased by about 500,000 bbl. in 1941, nearly all of the increase being in Pennsylvania grade. In 1940, the total production was 3,052,000 bbl. from 25,500 wells. In 1941 the total production was 3,547,534 bbl. from 24,801 wells. The increase in production is chiefly due to the Clinton pool in Clayton township, Perry County, which is briefly men- tioned later in this review. The number of oil wells, by grades of oil, and the total quantities produced are shown in Table ;. Annual oil production for five years is listed in Table 6. The average prices paid for crude in 1941 were slightly higher than in 1940 These 1941 prices, with dates of change, are shown in Table 7. The maximum production of natural gas in Ohio was in the year 1915, when the total was just under 80 billion cu. ft. The maximum consumption occurred in the year 1916, and was approximately 169 billion cu. ft. For the past several years, Ohio has ranged from eighth to eleventh, in order of gas production for the different states, being in tenth place in 1940. In the matter of consumption, however, Ohio remains in fifth place. Preliminary figures for 1940 indicate that production of natural gas increased II per

Jan 1, 1942

By Roshan B. Bhappu, Thomas J. Lien

The DYNA WHIRLPOOL Processor (DWP) is a cylindrical dynamic heavy media vessel. It is used to beneficiate fine ore sizes from one and one-half inches in diameter down to 65-mesh. Process units available treat up to 80 tons per hour. Units can be manifolded for higher capacity plants. Finely ground magnetite and ferrosilicon are used for media. , Installed capital costs are from $4,000 to $6,000 per ton hour of feed. Operating costs are from $0.30 to $0.50 per ton of feed. The DWP is used to beneficiate metallic and non-metallic ores and coal. The OCC Vessel is a static heavy media separator used to beneficiate coarse ore up to six inches in diameter and auto scrap. Process units available treat up to 300 tons per hour.

Jan 1, 1978

By L. H Levenson, Charles S. Barrett

The orientation of metal crystals and grains, both large and small, can be detcrmined conveniently and accurately without the use of X-ray apparatus. This seems to be appreciated by so few metallurgists that it may be useful to explain in detail the method we have found most satisfactory in the laboratory—the reflection of light from crystallographie etch pits. This note includes a description of a suitable inexpensive instrument and instructions for etching various metals and for plotting the data. As the stereographie projection is used to facilitate handling the data, this note may he considered as an appendix to an earlier review of the metallurgical uses of the stercographie projection.&apos; Various methods involving etch pits have been used by other investigators. Bridgman&apos;s method2 consists of attaching the specimen to a sphere (a transparent sphere is convenient4 , holding it at arm&apos;s length, and marking a spot on it when it has been turned so that the eteh pits reflect light into the eye of the observer from a lamp standing behind him. It has an accuracy of about 2" and is extrernely rapid. A greater accuracy can be obtained by having the reflected light fall on a screen, as has been done by Czochralski,5 Chalmers,6 and Schubnikov.7 All of these methods have been intended for undeformed single crystals. Tammann and his coworkers3,8 developed a method for estimating the number of grains in a polyerystalline aggregate having orientations in a given region of the stereographic triangle and thus obtained statistical information about deformation and reerystallization textures. While the method has had some use in recent years,9 it is not applicable to the majority of problems in physical metallurgy. Smith and Mehl10 determined orientations by plotting the directions of the sides of individual etch pits on a stereographic projection. The accuracy is limited to about 3" and the method requires careful polishing and high magnification.

Jan 1, 1940

By Charles S. Barrett, L. H. Levenson

The orientation of metal crystals and grains, both large and small, can be detcrmined conveniently and accurately without the use of X-ray apparatus. This seems to be appreciated by so few metallurgists that it may be useful to explain in detail the method we have found most satisfactory in the laboratory—the reflection of light from crystallographie etch pits. This note includes a description of a suitable inexpensive instrument and instructions for etching various metals and for plotting the data. As the stereographie projection is used to facilitate handling the data, this note may he considered as an appendix to an earlier review of the metallurgical uses of the stercographie projection.&apos; Various methods involving etch pits have been used by other investigators. Bridgman&apos;s method2 consists of attaching the specimen to a sphere (a transparent sphere is convenient4 , holding it at arm&apos;s length, and marking a spot on it when it has been turned so that the eteh pits reflect light into the eye of the observer from a lamp standing behind him. It has an accuracy of about 2" and is extrernely rapid. A greater accuracy can be obtained by having the reflected light fall on a screen, as has been done by Czochralski,5 Chalmers,6 and Schubnikov.7 All of these methods have been intended for undeformed single crystals. Tammann and his coworkers3,8 developed a method for estimating the number of grains in a polyerystalline aggregate having orientations in a given region of the stereographic triangle and thus obtained statistical information about deformation and reerystallization textures. While the method has had some use in recent years,9 it is not applicable to the majority of problems in physical metallurgy. Smith and Mehl10 determined orientations by plotting the directions of the sides of individual etch pits on a stereographic projection. The accuracy is limited to about 3" and the method requires careful polishing and high magnification.

Jan 1, 1940

By R. E. Carter, C. Wagner, F. D. Richardson

By means of inert markers of radio-platinum, it has been shown that cobalt metal oxidizes by out-ward diffusion of cobalt atoms through the oxide. Oxidation rates have been measured at various temperatures and oxygen pressures and have been found to agree with the rates calculated from the Wagner equation and the authors&apos; values for the diffusion coefficient of cobalt in the oxide. The distribution of radio-cobalt in growing oxide loyers has been accurately measured and found to be different from that predicted from the Wagner oxidation theory. Attempts have been made to measure the change of lattice parameter of the oxide with composition. SEVERAL investigators have shown that cobalt metal oxidizes according to the parabolic law,1-3 but no detailed study has been made of the oxidation mechanism. Cobaltous oxide has a metal-deficient lattice, but the defect concentration which is dependent on the oxygen pressure is only approximately known.&apos; From the similarities in the structures of "CoO" and "FeO" and the rate laws governing the oxidation of cobalt and iron, Gulbransen- as suggested that cobalt, like iron," oxidizes by diffusion of cobaltous ions through the oxide layer. To substantiate this hypothesis, he has attempted to measure the oxidation rate of cobalt as a function of the oxygen pressure but has been able to report only that the rate depends on a "small" power of the pressure. On the other hand, Preece," Valensi,&apos; and Arkharov&apos; all have suggested from indirect evidence that oxygen diffuses through the COO to the metal-oxide interface. The present authors, in a previous paper,&apos; have shown that the rate of diffusion of cobalt in cobaltous oxide is dependent on the oxygen pressure. In that investigation, they also found that cobaltous oxide disks made by complete oxidation of cobalt metal were porous at their centers (Fig. 5L, ref. 4). Both these facts strongly suggest that oxidation of the metal proceeds via outward diffusion of cations. In order to establish the mechanism unequivocally, oxidation experiments were made with inert radioactive platinum markers, and the dependence of oxidation rate on oxygen pressure was measured. In addition, an attempt was made to determine the form of the cation vacancy gradient, which the marker experiment showed must exist across a growing oxide layer. This was done by depositing radioactive Co on the surface of a cobalt disk and then measuring the tracer distribution across the oxide layer produced by partial oxidation of the metal. Finally, an X-ray examination was made in an attempt to find the expected change of lattice parameter of COO with oxygen pressure. Experimental The apparatus and materials used were substantially the same as those previously described by the authors.4 Marker Studies: The use of inert markers to follow oxidation reactions was first attempted by Pfeil" in 1929, and radioactive markers have recently been used by Davies et al.&apos; In the investigation reported here, the markers were applied as an (NH4)2PtCI6 slurry in several thin streaks across both faces of four disks of cobalt metal 1 mm thick and 14 mm in diameter. The disks were then oxidized almost to completion at 1200°C in pure oxygen. After oxidation, they were mounted and sectioned and auto-radiographs were taken to locate the markers. Oxidation Rate: The oxidation rate of cobalt was measured at 1148°C at oxygen pressures ranging from 0.0055 to 1.0 atm and at 1000°, 1148", and 1350°C under 1 atm of oxygen. The rate was deter-

Jan 1, 1956

US 4,181,520 - Direct reduction of iron oxide ore to sponge iron in a rotary kiln. Ore is fed into the kiln along with coal briquettes and passed through a preheating zone and then a reducing zone countercurrent to the flow of a kiln atmosphere which includes air or other oxygen-containing gas. The agglomerated coal is heated at such a rate that it disintegrates into fine particles in the preheating zone. The coal is largely recovered for reuse, while reduction is effected with a reducing flame rather than the coal. G. Reuter and W. Schnabel, assigned to Metallgesellschaft AG. Jan. 1, 1980. 6 pp. (75-36). Filed- 10-19-78 (952,870). Priority: West Germany, 1-14-75 (2,501,182). Same: British 1,532,969, dated Nov 22, 1978.

Jan 1, 1982

By A. J. Teplitz, R. J. Goodwin

A new type water shut-off for use in air drilling has been developed. The method has been 99 to 100 per rent effective in several different formations of inter-ranular-type porosity. Since costs for materials, time and equipment used are relatively small, the process should extend economies of air drilling to many new areas. The treatment involves a new technique for forming a water-inroluble precipitate within the pores of a rock. Advantage it taken of the difference in mobility of a liquid and a gas in porous media to achieve the greatest volume of precipitate in a given pore. Reactants selected for the laboratory (2nd field tests were aluminum sulfate solution and gaseous ammonia. This process has been tested in both intergranular and fractured-type porosities. It has consistently shut-of between 99 and 100 per cent of the water flowing from formations having intergranular-type porosity and perrlreuhilities ranging from a few millidarcise to over a darcy The treatment is not particularly suitable for shutting-off water from fractured formations although plugging of the order of 50 per cent or greater has been achieved in all such applications. Among advantages of the treatment are: (I) no reaction waiting rime after a relatively short placement time, (2) a low mate-rials cost of about $3/f1 of hole treated, (3) use of common service-type equipment for treatment, and (4) no unusual requirements for mixing and placement. INTRODUCTION In rotary drilling with air or gas it has been possible to increase bit life by tenfold and more than double rate of penetration over corresponding performance when drilling with mud. These factors have amounted to as much as 22 per cent savings on total cost of drilling a well. However, these advantages are rapidly lost when water is encountered in an air- or gas-drilled well because water interferes with the removal of cuttings from the hole and also gives rise to other difficulties. In attempting to combat water troubles, operators have commonly resorted to such measures as mist drilling, treatment with cement or chemicals, converting to conventional mud drilling, or setting casing. In many cases these measures have either been costly or ineffective. In an effort to overcome this problem, studies were undertaken to develop an effective and economical water shut-off technique for use in formations possessing inter-granular-type porosity. Extensive laboratory experimentation finally led to a unique method for producing a water-insoluble precipitate within the pores of a sandstone. The unique part of the treatment is use of a liquid and a gas to form the precipitate, and in this case the reactants used were aluminum sulfate solution and gaseous ammonia. The reaction between these two materials is shown in the following equation. Al2 (SO1)3 - 18 H20 6NH2? saturated Water- Solution Cat 2A1(OH)3 . n H20 3(NH4)2SO • n H20 Solid Solid That is, a solid precipitate consisting of aluminum hydroxide and ammonium sulfate is formed when ammonia reacts with aqueous aluminum sulfate. The aluminum hydroxide is insoluble in water and the ammonium sulfate, though soluble, can only be removed from the formation pores by diffusion—an extremely slow process. Although the precipitate formed by the reaction is not particularly firm, great strength is not needed for a precipitate to bridge and plug intergran-ular-type porosity. A flow path in such a system is extremely tortuous and involves a great variety of pore

By Clarence Zener

THEORETICAL considerations by one of the authors have led1 to the prediction that the dynamic internal friction of annealed metals has a broad maximum at a certain grain size. This prediction they have veri-fied2 for alpha brass. In the present paper the theory is extended to include the precise manner in which the internal friction varies with grain size on either side of the maximum. New experimental data are pre¬sented to test this extended theory. The physical basis for the type of internal friction that is being investi-gated lies in the interplay between stress and temperature. Just as local fluctuations in temperature give rise to local fluctuations in stress, so like-wise fluctuations in stress give rise to fluctuations in temperature. But temperature gradients give rise to necessarily irreversible thermal cur-rents, and hence to internal friction. The theory for this type of internal friction has been developed quantitatively,3 and has been experimentally verified,4,5 for the particularly simple case of the transverse thermal cur-rents accompanying transverse vibrations. Of more fundamental impor-tance are the intercrystalline thermal currents accompanying all types of vibration. The variation in stress across grain boundaries arises from the elastic anisotropy and at least partial random orientation of the individual crystallites. An exact quantitative treatment of the internal friction due to these thermal currents is of course out of the question. However, much information can be obtained from general arguments.1,6 Thus when the frequency of vibration f is low, or when the grain size d is small, adja-cent grains remain nearly in thermal equilibrium, and vibration proceeds isothermally with little internal friction. Again, when the frequency is high, or the grain size large, the heat flow per cycle is small, the vibration proceeds adiabatically with little internal friction. The internal friction will become a maximum in the transition region. The degree of adiabatic-

Jan 1, 1940

By William Blauvelt

Tun technical and engineering problems in the manufacture of coke are today the problems of the byproduct oven. Except in a few special localities, practically no beehive ovens have been built in the United States for the last 5 or 6 years except as renewals of old plants, and during these years the total number of beehive ovens in existence has been steadily falling. On the other hand, the number of byproduct ovens has increased from 4624 in 1911 to a total of about 7660 in operation at the end of 1917; with 2800 building, this makes a total of about 10,460 which will be in operation in 1918, or shortly thereafter. Preliminary Government estimates place the total production of coke for 1917 at 56,600,000 tons, the largest tonnage in the history of the industry. Of this 34,000,000 tons or 60 per cent. was beehive, and 22,-600,000 tons, or 40 per cent. was byproduct coke. Some time in 1918 the production of byproduct coke should pass the beehive output, and when the byproduct ovens now building are completed the total byproduct capacity will be about 40,000,000 tons of coke per. annum, which is over 70 per cent. of the record-breaking total coke production of 1917. The reasons for these changes in the coking industry are familiar to all of us, and need not be discussed here.

Jan 3, 1918

By J. Weertman

An explanation is advanced for the recent results of Barrett and Sherby on the high-temperature creep of fee metals. Their measurements indicate that metals with a low stacking fault energy creep at a much slower rate than metals with a high stacking fault energy. The explanation is based on the assumption that the rate of core diffusion is much smaller in partial dislocations than in perfect dislocations. An experiment is suggested to test this assumption. The explanation also requires that the jog density is small on widely split dislocations. SHERBY and Barrett1,2 recently established an important result in the field of high-temperature steady-state creep. They have shown that fee metals whose dislocations split into partial dislocations separated by a wide stacking-fault ribbon creep at a much slower rate than fee metals whose dislocations are not split appreciably. The creep rates in the two cases may differ by a factor as high as 6000. (For the purpose of comparison, the test temperature of each metal was chosen so that its rate of self-diffusion was equal to a standard value. Similarly the stress levels were such that the ratio of the stress to an appropriate elastic modulus was the same for each metal. In all cases the stresses were sufficiently low that the steady-state creep rate was proportional to the stress raised to a power.) It is the purpose of the present paper to attempt an explanation of this interesting and significant result of Sherby and Barrett. The activation energies of high-temperature creep of the metals tested by Sherby and Barrett (aluminum, nickel, copper, and silver) were equal to their self-diffusion activation energies. Hence it appears reasonable to assume that this type of creep is controlled by a dislocation-climb process, which in turn is controlled by the diffusion of vacancies to or from dislocation lines. (It will be assumed that the diffusion of interstitial atoms is unimportant in the climb process. The analysis could be repeated for the case in which interstitial atoms are important.) In prior papers374 I have treated dislocation climb by using the assumptions that core diffusion is extremely fast down a dislocation and that a dislocation always maintains an appropriate vacancy concentration in its immediate vicinity. In this

Jan 1, 1965