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By Makoto Ohlsuka

The ternary Ni2MnGa intermetallic compound is an intelligent material which has both a ferromagnetic property and a shape memory effect (SME). The use of the shape memory alloy films for an actuator of micro-machines is very attractive because of its large recovery force. The purpose of the present study is to investigate the effects of fabrication conditions and to clarify the relationships between these properties and fabrication conditions of the Ni-Mn-Ga films. The Ni-Mn-Ga films with a thickness of nearly 5 um were deposited with a radio-frequency magnetron sputtering apparatus using a Ni50Mn25Ga25 or Ni52Mn24Ga24 target. They were heat-treated at various temperatures between 873 and 1273 K for homogenization and ordering and then cooled in a furnace. The composition of the films depended on the sputtering power. The as-deposited films were crystalline and had columnar grains. After the heat treatment the grains widened and the grain boundary became indistinct with the increasing heat treatment temperature. The martensitic transformation temperature of the heat-treated films increased with increasing nickel content. Furthermore the effect of plastic deformation and constraint aging on SME is also investigated. After plastic deformation, the two-way SME was shown through the martensitie transformation and its reversion, The intensity of X-ray diffraction peaks from stress-induced martensitie phase was found. The constraint-aged films also showed the two-way 3ME by thermal cycling.

Jan 1, 2003

By Shun Myung Shin, Kang Jeong, Kyoungkeun Yoo, Jin Koo, Dong Hyo Yang, Soo Sohn

"The optimum discharging condition to dismantle the batteries without explosion was investigated to recycle the lithium primary batteries, which could be exploded by heating too much or crushing. The 3 waste lithium primary battery cells were discharged with 500 cm3 of 0.5 kmol·m-3 sulfuric acid. Fe concentration and pH increased rapidly after 3 days at 35? and after 1 day at 50?. Chromium concentration increased by 4 days at 35? and 2 day at 50?and then decreased, and nickel concentration was very low. Because Li concentration increased gradually, Li became dissolved after the dissolution of cover material. When the discharged batteries were shredded, the batteries discharged at 50°C were not exploded and those discharged during 3 days at 35°C were exploded. This result shows that the waste batteries could be stabilized within 1 day at 50°C and 4 days at 35°C. Introduction Lithium has some advantages for battery e.g. it is the lightest metals and also has the highest electrochemical potential at 3.04V[1]. For over thirty years lithium primary batteries became famous for their performance in various applications such as IT, medical, and military[2,3]. They gained a reputation for their long shelf life, constant voltage, wide operating temperature range, and low self-discharge characteristics[3-5]. World primary lithium battery market was expected to grow from $820.6 million in 2003 to $1,1355.3 million in 2010 (http://www.frost.com, Frost & Sullivan)[2-4]. The lithium primary batteries have very various sizes and components. Lithium batteries are made with lithium metal as anode active material and non-aqueous solvent as electrolyte. As cathode active material, various kinds of materials were used such as manganese dioxide (nominal voltage, 3.5V), thionyl chloride (3.6V), and carbon monofluoride (3.0V). In Korea, 50 % of the spent lithium primary batteries must be recycled because spent lithium primary batteries have been listed in EPR (Extended Producer Responsibility) of the enforcement degree of the act on the promotion of saving and recycling of resources. However, the batteries have been landfilled since there is no economic method to recycle the batteries in Korea[2,3]. When the batteries were heated too much, charged, pierced, over discharged, or short-circuited, the batteries explode because lithium reacts violently with water or air and because contents such as lithium, electrolyte, and sulfur become flammable by high temperature[4]. Therefore, it is so difficult to recycle safely the spent lithium primary batteries."

Jan 1, 2008

By Kafui Nyavor

The indirect, and the direct contact mechanisms of bacteria oxidation of sulfides were studied using Thiobacillus ferrooxidans and pyrite. The aim was to determine which of the two generally aeeepted mechanisms played a dominant role, if any, during acid mine drainage (AMD) formation from the oxidation of sulfide minerals. The results show that at a pH of 4.5 where T. ferrooxidans are quite active, but where initial chemical oxidation of pyrite to Fe2+ is limited, the bacteria were unable to directly oxidize pyrite to any significant extent. Whereas, in the presence of Fe2+, T. ferrooxidallS assisted oxidation of pyrite by the indirect mechanism was observed and sustained over the pH and Eb range where the bacteria is active. The results lead to the conclusion that the direct contactmechanism of pyrite oxidition by T. ferrooxidans is insignificant. The predominant, and possibly the only, pathway involves the indirect bacteria oxidation of available Fe2+ to Fe3+, which in turn oxidizes FeS2 to generate additional Fe2+ and acidity in a cyclic process.

Jan 1, 1996

By M. Drozd

Multi-use pad operators require an efficient and economic method to destroy cyanide in their process residues so new material can be stored on the pad and leached. Operators of the dedicated or single-use pads require an effective cyanide destruction method for pad closure. Cyanide destruction can be accomplished by utilizing oxidants such as hydrogen peroxide or calcium hypochlorite, or by utilizing ferrous sulfate which sequesters the cyanide in strong acid dissociable complex. Ferrous sulfate can be the preferred method of cyanide destruction because it is a less costly chemical, reaction rates are almost immediate and unlike oxidants, it can penetrate the total depth of a pile without being destroyed by side reactions. Literature indicates that the (Fe(CN)6)-4 com~lex is produced slowly but it appears that complexes such as Fe(CN)4(H20)2-or Fe(CN)4(OH)2)-4, are formed quickly and should have no U.V. sensitifity, unlike (Fe(CN)6)-4. Stoichiometry of the testwork indicates that Fe«CN)4(OH)2)-4 complex may be the species formed. The usage of ferrous sulfate has the advantage of being able to bring ~ level down that divalent metal ions such as Cu++, Cd++, Hg++, Pb++ and Zn will form insoluble complexes and precipitate from solutions does not destroy weak acid dissolvable complexes and can leave a heavy metal problem behind after cyanide destruction.

Jan 1, 1990

Al2O3,-WC Composite powder for cutting tools was synthesized by self-propagating high-temperature synthesis using A1 powder as a reducing agent. WC, W2C and Al2O3 were concurrently formed in WO3Al-C system. It was found that the complete reaction was achieved with excessive addition of carbon and appropriate processing parameters such as degree of dilution, particle size of aluminum, compaction pressures of green pellets and carbon source. The final product which was leached by 50% HN03+HF diluted solution was consisted of Al2O3-55wt% WC having 2-3um of mean particle size.

Jan 1, 1999

By Suchun Zhang

The alkaline oxidation of refractory gold concentrates containing arsenopyrite and pyrite at ambient temperatures and pressures has been found to be accompanied by the simultaneous dissolution of gold without the addition of cyanide. A detailed study has been made of the kinetics of the oxidation of the pure minerals and of several concentrates. The reaction products of the oxidation of arsenic and sulphur have been monitored using chromatographic techniques. In the case of arsenopyrite, thiosulfate, monothioarsenate, arsenate and sulfite are the principal products while thiosulfate has been confirmed to be the dominant product of pyrite oxidation. Gold, either as added powder or as a constituent of the concentrates has been found to dissolve simultaneously during the alkaline oxidation of both arsenopyrite and pyrite, and this appears to be associated with the in-situ formation of thiosulfate as a lixiviant. The effects of temperature, stirring speed, oxygen partial pressure, alkalinity and pulp density on the oxidation of arsenopyrite and the dissolution of gold have also been investigated. Keywords: Gold, dissolution, arsenopyrite, pyrite, alkaline, oxidation, thiosulfate, thioarsenate

Jan 1, 2005

By M. K. Mohan

Lead recovery from process solutions contributes not only to the conservation of resources but also clean environment. Zeolites are natural aluminosilicates, which finds applications as catalysts and in wastewater treatment. In the present investigation, studies were taken up on the processing of Pb from process solutions by zeolites. Effects of pH of the solution, time and type of zeolite viz. chabazite, mordenite, erionite and clinoptilolite on the removal of Pb from solutions was investigated. Rate of sorption was found to depend on the pH of the solution and about 99 pct. recovery was observed at pH 6. Optimal conditions were established for the maximum recovery of lead from process solutions. Possible sorption mechanisms were proposed. The calculated adsorption constants calculated from Langmuir and Freundlich equations showed that the adsorption of lead on chabazite was strong.

Jan 1, 1999

By Zhitong Sui

Based on several case studies on the precipitating behavior of valuable nonferrous metal compounds (VNMC) in molten slags a green technology for the recovery of VNMC from molten slags was proposed. This technology involves three steps: (I) The selective enrichment of the dispersed VNMC into the designed mineral phase in the molten slag; (2) The selective coarsening of the designed mineral phase to a critical grain size in the molten slag; (3) The selective separation from tailing of the grown mineral phase in the solidified slag by dressing or hydrometallurgy processes. This is a clean and low cost technique and has a great capacity to deal with a large quantity of slags. The utilization of the recovered VNMC such as Titanium, Boron, Vanadium compounds was summarized as examples of application. It was confirmed by experiments that the precipitating behavior of the designed mineral phases like Perovskite(CaTiO3), Suanite(2MgO*B2O3) and Sincosite(CaOoV2O5*P2O5) in molten slags is obviously affected by operation factors such as temperature, chemical composition, heat-treatment, additives and so on. The precipitating kinetics and mechanism of the VNMC from molten slags during solidification processes were also investigated.

Jan 1, 2003

By Xiang (Frank) Chen, Mikhail A. Sokolov, Randy K. Nanstad

"Nickel-base Alloy 617 is being considered as a structural material for application in the secondary heat exchanger of the New Generation Nuclear Plant, a very high temperature gascooled reactor. Thermal aging of Alloy 617 plate and welds is being performed with tensile, Charpy impact, and fracture toughness tests conducted at temperatures to 950°C. Results of testing for thermal aging to 5,300 h have been obtained and are presented; varying effects of thermal aging temperature and time on fracture toughness are observed. The 9Cr-1MoV (Grade 91) ferritic steel is a candidate for structural applications in the sodium fast reactor. Fracture toughness testing of unaged Grade 91 steel has been performed to evaluate specimen size effects in preparation for future testing of the material in the thermally aged condition. Results for material in the mill-annealed and heat treated conditions are presented and show that this heat of Grade 91 steel does not indicate a small specimen bias on the fracture toughness Master Curve reference temperature.IntroductionThe behavior of advanced engineering materials will be a critical factor in the performance of Generation IV reactors. In the case of materials utilized for reactor internals and pressure vessels, the effects of irradiation and long time thermal aging are major issues. The environmental conditions for some of the Gen IV reactors are generally beyond present day reactor technology, requiring new experimental data as well as analytical predictions of expected behavior of candidate materials at conditions for which there are only sparse or no experimental data. The radiation environments and several key materials issues for some Gen IV systems are summarized in Section 5 of [l] as a starting point for modeling and microstructural analysis of Generation IV materials. More detailed descriptions of materials research and development needs and recommended activities for the SCWR, VHTR, and GFR are provided in references [2, 3, 4], respectively. Mansur, et. al. provide an interesting comparison of materials needs for Generation IV reactors to corresponding needs for fusion reactors and spallation neutron sources in [5]. The two primary candidate reactor systems currently undergoing significant research and development by the U.S. Department of Energy (DOE) are the New Generation Nuclear Plant"

Jan 1, 2012

By K. Yamada, T. Takaoka, A. Ozeki, M. Yamaga, Y. Kawai, S. Nishioka, Y. Kikuchi

"Recently, smelting reduction of chromium ore in BOF has been actively investigated as a key unit process for an innovative future stainless steelmaking. The prominent feature of this new process route is energy and process saving, and production cost saving. The development is already in the midst of application to the commercial production, however there still remain the following key technologies to be established for the full use of the process. One is a speed up of the reduction of chromium ore to match with sequential continuous casting, and the other is efficient combustion of carbonaceous materials in BOF to reduce their consumption, and hence to assure the steel quality. High degree of post combustion technology and new charging technology, i.e., ore-coal-flux-oxygen mixed injection, could be effective for those two subjects. In 2000 or beyond, the new process would have become quite popular owing to the establishment of those key technologies.Introduction Since stainless steel was invented, its production has continued to expand because of its attractive combinations of functions of excellent corrosion resistance, good formability, a pleasing appearance, and a wide range of strength levels. New types of stainless steels as well as new applications are continually being developed.Compared to the production of ordinary steels (1), stainless steel production (2,3) shows steady growth worldwide, while the former production remains on the same level, as Figure 1 shows. It can be estimated that future production would show further growth since materials consumer demands are more fashionable, or more functional, which could be satisfied by stainless steels.Thus market needs would be met, if it could be produced with reasonable production cost. The emergence of an innovative production technology is then potentially requested as VOD and AOD processes have emerged, which has saved substantial production cost. This paper describes a possibility of a future stainless steelmaking process, which uses the in-bath smelting reduction of chromium ore in BOF, and which would save production as well as energy cost."

Jan 1, 1988

By Michele L. Bustamante, Gabrielle Gaustad

In recent years, t h e future supply of tellurium has been called into question due to the anticipated rapidly increasing demand from thin film cadmium telluride photovoltaics. Since tellurium is produced as a byproduct of other extractive processes – principally, the electrolytic refining of primary copper sulfide ore – it is important to explore the dynamics of the parent metal extraction and processing – in this case copper – when attempting to answer this question. This research explores the changing landscape of global copper production; introducing system diagramming and the concept of byproduct intensity (BPI) to illustrate concerning downward trends in tellurium supply potential. Upon closer inspection, it is concluding that, while a likely contributor to these downward trends, the increased use of non- traditional copper production techniques alone are not responsible; other factors include market substitution and incomplete data reporting. Additionally, a review of literature on tellurium recovery processing reveals a promising outlook for future supplies; highlighting potential for improvements in yield, which allow producers to make better use of what is available, even in the face of suppressed BPI.

Jan 1, 2014

By G. Van Weert

The pellet reactor was developed approximately 20 years ago in the Netherlands for softening drinking water. Since then, some 35 plants have been built, ranging in capacity up to 8500 m3/h. Applications now also include removal of phosphates and fluorides and the production of metal carbonates and sulphides from waste streams. The pellet reactor consists of a fluidized bed, wherein the process solution is thoroughly mixed with the precipitation reagent at special inlet nozzles to give over-saturation of the compound to be precipitated. In water softening applications, the compound is CaCO,. In the case of nickel or other metal waste streams, Na2CO3 solution is added in sufficient amounts to precipitate metal (hydroxy) carbonate on the fluid bed particles. These grow typically to dense spheroids, which are removed when they reach 0.8 to 1.0 mm diameter. These spheroids are easily dewatered, free flowing and low dusting. The latter property is becoming an attractive advantage in connection with new plant hygiene regulations. The operation of a 60 cm diameter pellet reactor on nickel containing plating waste is described and the properties of the produced nickel carbonate spheroids are discussed.

Jan 1, 1993

By Rauno Peippo

Horizontal Waste Heat Boiler (WHB), today's proven and dominating technology for copper smelter gas cooling, has been utilized by the industry for over half a century. During this time development has taken place in geometry, flow characteristics, cleaning technology and design details. This development has been driven by improved understanding of the specific process requirements, gained both by wide experience and by utilizing new emerging design tools, like computer flow modeling. It had to wait till mid 90's to unite effective and proven Spring Hammer cleaning technology and the process benefits gained by gas guiding vanes or baffle wall in the copper smelter WHB design. The new design has demonstrated improvement in gas cooling efficiency and the process conditions down stream in form of less dust sticking problems in the boiler and precipitators. Reduced weak acid production has also been reported as a result of the design. The theoretical aspects, computer flow modeling results and actual benefits measured in old smelting line modernization are discussed. Experience £tom modernization projects such as Phelps Dodge, Atlantic Copper, Mexicana de Cobre, and Nippon Mining, Saganoseki, are discussed. In mechanical design there has been development resulting improved gas tightness with less corrosion and better control of dust sulfation. An essential improvement is the integration of the boiler hopper and dust removing conveyor. Having no steel plate casings in the hopper and conveyor section but using of boiler tube membrane instead eliminates thermal expansion differences. The dust conveyor will be effectively cooled against hot dust lumps falling down while the acid dew point corrosion is prevented in the cooler sections of the hopper. Conceptual features are presented of a new generation Copper Flash Smelter WHB presently under construction at Boliden Mineral, Skelleftehamn, Sweden, where the latest development and innovations are adopted.

Jan 1, 1999

By Takeshi Nagano

"Prior to discussing future trends of non-ferrous metals smelting and refining, the past developments are looked back. Social and economic environments in Japan over the past two decades are reviewed. Technological developments to comply with these environments are explained, taking for examples the cases of the Mitsubishi continuous smelting and converting process and Onahama's jumbo tank system for copper tankhouse. After considering the factors which will influence the improvements in non-ferrous processing, future trends are forecasted generally for copper, zinc, lead, aluminum and rare earth metals. Recent development works in Japan for the future are also introduced. In the discussed area, it appears that the emergence of new innovative processes would be difficult. The progress will be made rather toward the sophistication of the existing technologies, utilizing the advancement of the related technologies such as computers, electronics, etc. IntroductionThis paper discusses the future trends of non-ferrous metals smelting and refining on the occasion of the international symposium, ""The Metallurgical Processes for the Year 2000 and Beyond"".It is considered that the improvement of technology is greatly influenced by the social and economic environments which surround it. From this standpoint, review was made of Japanese case over the past two decades. Various new technologies were developed also in the non-ferrous metal world to comply with the requirements under the above environments. The examples are described in the cases of the Mitsubishi continuous smelting and converting process and Onahama's jumbo tank system for copper electro-refining.After foreseeing the major factors which will affect the technological developments in the future, the trends are forecasted for copper, zinc, lead, aluminum and rare earth metals generally. Some development works in Japan, which will give suggestions for future trends, are also introduced in some detail."

Jan 1, 1988

By M. Moinpour, E. Liao, C. Y. Aw, D. J. Brown, P. W. Cheung

"Currently, silicon-based insulated-gate field-effect devices are being widely developed as the basic structural elements in a new generation of chemical microsensors. In this paper, we discuss some of the process considerations related to the fabrication of the Chemically Sensitive Field-Effect Transistor (CHEMFET). This ion-sensitive CHEMFET (or ISFET as it is often called) can be used for pH measurements (i.e., as a pH sensor) when the gate insulator of the electrolyte/insulator interface is made of Si3N4 obtained by the LPCVD method. Effects of processing parameters such as the Si3N4 deposition rate, gas composition, total flow rate, annealing treatment, etc. on Si/Si02, Si/Si3N4 and Si/Si02/Si3N4 structures are discussed in relation to the CHEMFET fabrication. Their effects on the electrical characteristics and chemical response of the sensor are also examined. Capacitance-Voltage (C-V) measurements and ESCA analysis have been used to interpret the results. The Si3N4/Si02 double dialectric layer provides improved ion blocking for the gate insulator in electrolyte solutions with enhanced pH sensitivity over time. The stability and performance of the fabricated CHEMFET sensors were tested by measuring the pH sensitivity in various storage conditions. The SEM analysis was used to evaluate the hydration effect at the ISFET's gate insulator with respect to different storage conditions.IntroductionThere has been a continuous interest in the development and fabrication of various chemical microsensors for chemical and biomedical applications over the last fifteen years. The application of semiconductor (particularly silicon) technology to the area of sensor fabrication has led to an emergence of a new generation of miniaturized, microelectronic, solid-state chemical sensors. There are numerous clinical situations where continuous monitoring of body electrolytes concentrations such as Na+, K+, Ca+2 , etc. and blood gases (pH, Po2 , and PC02) would be essential for the effective diagnosis and management of patients under critical conditions. Solid- state microsensors can be used for direct and continuous in vivo measurement of the above parameters in most instances."

Jan 1, 1988

By I. Goy D. Gaballah

Decontamination of synthetic K2Cr2O 7 solutions containing 10 to 1000 ppm of hexavalent chromium using chemically treated barks have been studied at a laboratory scale. Metal removal from solutions depends on the pH, the initial concentration and the bark species. The use of a pulp density of 2 % in an agitated flask at the optimum pH for 2 hours leads to a percentage chromium removal of about 95 of the initial metallic ions content. Other trials conducted by column percolation permit the determination of the maximum retention capacity of the treated bark. Depending on the bark species, oak or pine, the rate of saturation is 110 and 215 mg of Cr per gram of bark respectively. The incineration of the metal charged barks gives recyclable, ashes containing 36 and 54 % of chromium metal for the oak and pine barks respectively. Experiments, of Cr6+ removal from industrial effluents containing up to 1800 ppm have been carried out on the semi-pilot plant scale. They have lead to the elimination of about 90 % of hexavalent chromium from this industrial waste solution. Further studies are conducted in order to define the hexavalent chromium binding mechanisms on bark constituents.

Jan 1, 1992

By Takashi Miyamoto, Hideo Nakae, Hideki Yamaura, Takeshi Yanagihara

"For the production of partially composed metal matrix composites, namely discontinuous MMCs, using a casting· process, the interpenetrated phase composites with SiC particles were fabricated by pressureless iDfiltration using molten Al-Si alloys. This process is based on a wetting phenomenon, therefore, we discussed the technique based on the reactive wetting. The SiC particles coated by diluted water glass were sintered in a mullite Tammann tube and simultaneously infiltrated with molten Al-Si alloys in air at 1173~1573K. As for the improvement of the wettability between the SiC and the liquid aluminum alloy, Fe3O 4 powder was mixed with the water glass due to the thermit reaction between Fe3O4 and molten aluminum alloy. In some experiments, pure aluminum powder was placed on the sintered SiC to increase the interfacial area and the chemical reaction between the sintered Sic. and the melt. By combining these conditions, we succeeded in the complete infiltration without pressure at 1173K.IntroductionAs is well known, the mechanical properties of metal matrix composites (abbreviated MMCs) are superior than that of ordinary metals. However, their use has not been widely accepted because the production cost is very high due to their poor machinability. Therefore, the production of partially composed, namely discontinuous MMCs, by as the Lanxide process [l,2] has been investigated for many years. The Lanxide process, it takes a long time, sometimes up to 10h, in a nitrogen atmosphere for the infiltration. Therefore, the cost will be higher for common use. On the other hand, a high 'pressure process has been adopted for the production of discontinuous MMCs by the Toyota Motor Corp.[3]."

Jan 1, 2000

By Hu Long

In this, the first systematic study of the oxidation of orpiment (As2S3) in sulfuric acid solution under oxygen pressure at temperatures above 170°C, the effects of retention time, temperature, particle size, oxygen partial pressure, the concentration of sulfuric acid and pulp density were evaluated. The effects of cupric and ferric ions on the oxidation rate of As(III) to As(V) were also examined. The products of oxidation are As(III), As(V), SO42- and elemental sulfur. At temperatures ranging from 170 to 230°C, most of the arsenic was found to be in the trivalent state, and oxidation to As(V) with oxygen was very slow. This was confirmed by attempting to oxidize a synthetic arsenious solution. However, the rate of oxidation of As(III) to As(V) is rapid in the presence of ferric ion. Elemental sulfur was found at all temperatures investigated, which can be further oxidized to sulfate at high temperature.

Jan 1, 1999

By Cong Wang, Kexin Jiao, Yongan Zhao, Haibin Zuo, Jianliang Zhang

Traditional refractory materials for blast furnace hearth lining are mainly composed of carbon bricks and the ceramic cup. However, these materials can’t meet the demands for long service life design of blast furnaces. In this paper, a new refractory called carbon composite brick (CCB) was introduced, which combined the advantages of carbon bricks and the ceramic cup. In this case, the resistance of the CCB against corrosion was equal to the ceramic cup and the thermal conductivity of the CCB was equal to carbon bricks. From the results of more than 20 blast furnaces, the CCB could be well used in small blast furnaces and large blast furnaces. In the bad condition of low grade burden and high smelting intensity, the CCB gave full play to the role of cooling system, and effectively resisted the erosion of hot metal to improve the service life of blast furnaces.

Jan 1, 2015

By A. E. Isaacson

The U.S. Bureau of Mines is studying the effect of supercritical water, at 400' C and 3,500 psi, and subcritical water, at lower temperatures and pressures, on mixtures of minerals and metals to determine the possible applications of water at high temperature and pressure for processing these materials. This research was conducted using a flow-through bench-scale system. Copper-bearing minerals studied were chalcocite, chalcopyrite, covellite, and cuprite. In general, mixtures of copper minerals and pyrite reacted to form bornite. Intermediate phases formed were chalcopyrite and digenite. Similar reactions occurred between pyrite and metallic copper. A mixture of chalcopyrite and pyrite was inert in supercritical water'. The reaction between cuprite and metallic zinc yielded metallic copper. The cuprite was reduced by hydrogen generated by the reaction between metallic zinc and water. None of the reactions occurred exclusively in supercritical water, but also occurred in water at high temperature and pressure below the critical point. 'Experimental results did show that a dual-reaction process, consisting of solid-state diffusion and fluid transport, was occurring.

Jan 1, 1989