Search Documents

By Meifeng Zhi

Separation of uranium and molybdenum in the alkaline leach solution of a U–Mo ore was studied. A process of acidification-solvent extraction-precipitation uranium and molybdenum was determined. The influences of solution acidity and phase ratio of acidic scrubbing on separation of uranium and molybdenum were examined. The molybdenum extraction equilibrium isotherm was drawn. The results show that the separation of molybdenum and uranium can be achieved by acidifying the alkaline leach solution, solvent extracting molybdenum using trialkylamine at equilibrium pH 2.5, and scrubbing the loaded organic phase using sulfuric acid solution. The strip solution can directly precipitate ammonium molybdate. Uranium can be directly precipitated from the raffinat

By Hui Zhang

The leaching behavior of palladium powder in aqueous solutions containing NaCI or N'H4Cl was investigated. Cupric ion was used as an oxidant for the dissolution reaction. The effect of a number of leaching parameters such as temperature, concentration, stirring speed and surface area on the leaching rate was studied. The leaching system containing chloride and cupric ion was found to be very effective for the dissolution of metallic palladium. Based on the experimental results the overall leaching rate was believed to be controlled by a chemical reaction step. The dissolution rate of palladium was found to be first order with respect to the concentration of cupric ion and second order with respect to the concentration of chloride.

Jan 1, 1996

By G. Kyle Green

Zirconium chlorinator residues contain an array of rare earths, scandium, unreacted coke, and radioactive thorium and radium. Because of the radioactivity, the residues must be disposed in special waste containment facilities. As these sites become more congested, and with stricter environmental regulations, disposal of large volumes of wastes may become more difficult. To reduce the mass of disposed material, the U.S. Bureau of Mines (USBM) developed technology to recover rare earths, thorium and radium, and unreacted coke from these residues. This technology employs an HCl leach to solubilize over 99% of the scandium and thorium, and over 90% of the rare earths. The leach liquor is processed through several solvent extraction stages to selectively recover scandium, thorium, and rare earths. The leach residue is further leached with an organic acid to solubilize radium, thus allowing unreacted coke to be recycled to the chlorinator. The thorium and radium waste products, which comprise only 2.1% of the original residue mass, can then be sent to the radioactive waste facility.

Jan 1, 1995

By M. Opler

Presently, only a few large copper refineries are able to produce Grade A cathodes from copper scrap. Today's technology needs large plants for smelting, converting or refining the main impurities and casting the anodes for electrolytic refining. A new ECUPREX® PROCESS, by-passes all pyrometallurgical operations and produces directly copper cathodes starting from copper scrap with high lead and tin contamination. Copper scrap from chopped cables, copper cements and electronic scrap are suitable feed for ECUPREX® PROCESS. This process uses a non-conventional electrolyte and produces a surprisingly high quality, smooth cathode assaying only few ppms of total metallic impurities. Bench-scale work followed by a successful mini-pilot plant run, has led to the construction of an operating pilot plant equipped with a 1,000 Ampere cell. The results of the operations of this pilot plant are presented and described in this paper.

Jan 1, 1995

By M. Krishna, Jayagopal Uchi1, Shanta Sastry, B. M. Satish

"A well-considered composite of ZA-27 reinforced with weight percentage 0, 2, 4, and 6% of alwninite particulate has been made by compocasting technique. The elastic properties of ZA- 27 /alwniniute particulate composite were determined by using U1M. The results showed that the modulus of elasticity and UTS of the composite gradually increases with increase in the wt.% of reinforcement. However, the overall ductility decreased monotonically with an increase in reinforcement. The results of these tests· as well as the predictions of several model~ for composite strengthening available in the literature were compared with experimental results. The data observed from Young's modulus by measurements studies were compared with theoretical results predicted by Eshelby model.IntroductionMetal matrix composites (MMCs) have received increasing attention in _the recent decades as engineering materials. The introduction of a ceramic reinforcement into a metal matrix produces a composite material resulting in an attractive combination of physical and mechanical properties that cannot be obtained with monolithic alloys. Particulate reinf9rced MMCs among the discontinuously reinforced MMCs have attracted quite a lot of attention both in the industrial sectors and the academic communities. There is an increasing need for knowledge about the processing techniques and mechanical behavior of particulate MMCs in view of their production getting enhanced and their commercial applications becoming wider [I]. Interest in particulate reinforced MMCs is mainly due to easy availability of particles and economical processing techniqu"

Jan 1, 2000

By R. Nilsson

In the present work the sulphide capacities of Ca0-Mn0-Si0, ternary slags have been measured in the temperature range 1798 - 1873 K by equilibrating the slag with a gas-mixture containing CO, CO,, SO, and Ar. The results are compared with the data reported in literature. A theoretical model has been developed in the present work where the sulphide capacity is expressed as a function of the slag composition and temperature. The model enables the estimation of sulphide capacities of complex slags with a knowledge of the capacities of simpler systems.

Jan 1, 1994

By Lucas Nana Wiredu Damoah, Lifeng Zhang

"Increasing demand for Solar Grade Silicon (SoG-Si) due to rising interest in renewable energy has lead to increased SoG-Si Top – cut scraps generated from the multi-crystalline silicon making process. Due to the high cost of SoG-Si and the potential to use the top-cut scraps as feedstock material, there has been increased effort to develop cost effective and efficient technologies. As a result, several methods to recycle the top-cut scraps are currently been applied, and researched. These include settling under gravitation field, which is a slow process to be industrially applicable. Natural settling of inclusions by gravitational force is a slow process and not attractive to the industry. Recent experiments on Top-cut SoG-Si scrap under high frequency, high voltage, electromagnetic field showed that SiC inclusions settled within a short time to the bottom of the crucible and the characteristic rod-like morphologies of Si3N4 inclusions in SoG-Si were not detected. This study investigates the enhanced settling of SiC inclusions and the behavior of Si3N4 particles under the influence of high frequency, high voltage, electromagnetic field in Top-cut SoG-Si.IntroductionThe photovoltaic industry depends on silicon based PV materials either as single-crystalline silicon, or multi-crystalline Si (MC-Si), or amorphous Si [1] for over 90 % of its market share. [2] MC-Si produced by directional solidification of solar grade silicon melt dominates the silicon PV market. During the directional solidification process, SiC and Si3N4 particles within the melt are pushed by the solidification front to the top of the ingot which is the last to solidify. Therefore the top of the ingot is cut generating what is known as top-cut solar silicon scraps. The Si3N4 particles are mainly from the coating material at the inside surface of the silica crucible and from air absorption during the solidification process. The SiC particles mainly stem from the carbon reduction process of the primary production of silicon [3]. Due to the growth of the PV industry as a result of global demand for clean, reliable, and affordable energy [4], there is the need to develop new methods to compliment exiting ones to recycle SoG-Si waste (e.g. top-cut) for sustainability."

Jan 1, 2012

By A. V. Kuznetsov, R. I. Kamkin, V. M. Paretskiy, A. Y. Mamaev, V. P. Bystrov, A. S. Vernigora

"Vanukov furnace technology is an efficient, proven pyrometallurgical injection technology, used extensively in Russia and Kazakhstan for a number of different applications. The technology was most widely adopted for processing copper sulfide concentrates for matte in smelters in Norilsk, Revda (Russia) and Balkhash (Kazakhstan). The following applications also were developed and tested at industrial scale: treatment of sulfide lead and lead-zinc concentrates, laterite nickel ore, production of cast iron, treatment of antimony gold-containing ores, and municipal solid waste. In this paper, current experience of Vanukov furnace application to these technologies is described with a number of general development trends and new areas of application.IntroductionAt the present time, the Vanukov process, developed at the Moscow State Institute of Steel and Alloys at the Department of metallurgy of non-ferrous, rare and noble metals with collaboration with other research organizations, is a highly efficient technological solution for processing different kinds of raw materials. The process was invented by Professor Andrey Vladimirovich Vanukov, whose research work began in 1949. From 1956 to 1975 test runs of the technology were carried out at the smelters in Norilsk and Balkhash. In 1976 a pilot Vanukov furnace was built in Ryazan. Furnace designs was modified to suit the various test programs. A major objective of each experiment was the determination of optimal working conditions for processing different types of raw materials such as copper, copper-nickel, copper-zinc, lead or pyrite concentrates, and materials containing secondary lead and zinc. After the death of Andrey Vladimirovich Vanukov in 1986, this technology and furnaces based on the technology were named after him: “Vanukov process” and “Vanukov furnace”. Today, the following furnaces based on Vanukov technology are either working or were tested at semi-industrial scale: three in Norilsk, two in Revda (Russia) and two in Balkhash (Kazakhstan) for treatment of copper sulfide concentrates for matte, one in Orsk (Russia) for processing laterite nickel ore, one in the Buruktal plant (Russia) for antimony gold-containing ores for antimony oxide sublimates and gold-containing metallic antimony, and one in China for processing sulfide lead and lead-zinc concentrates for production of black lead and zinc-containing sublimates."

Jan 1, 2011

By K. Pagalthivarthi, P. V. Desai

"During solidification of alloys, many inter-related physical processes, such as melt convection, mass diffusion, heat transport, macrosegregation and melt-undercooling occur. Several research workers have studied one or more of these effects separately. To answer important questions on solidification behavior, an overall approach interrelating the processes is necessaryAs a first step toward accomplishing the overall modeling, the freezing of a binary liquid metal is examined. The various stages during freezing of the alloy are critically described to build a continuum model for the entire process. Diffusive mixture theory is used to write the conservation equations for the liquid and the mushy zones. The concept of local thermodynamic equilibrium in the presence of curvature effects is used to restrict the number of degrees of freedom within the mushy zone. Constitutive equations relating flux quantities and affinities, the governing differential equations and boundary conditions are discussed briefly for the freezing process.IntroductionA solidification study encompasses such facets as solifidication time, microstructure, macrosegregation of the solute, shrinkage effects and soundness of the casting. Influence of one or more of the coupled heat and mass transfer phenomena such as local solute redistribution, thermosolutal convection, melt undercooling at dendrite tips and heat dissipation to the ambient have all been previously examined [1-3J. Several studies have examined the individual facets of alloy solidification as isolated processses. In fact, the transport processes occur simultaneously and a comprehensive model should include their inter-relationships. In particular, some of the existing studies of the mushy zone [4-6J do not emphasize thermodynamic completeness. This work represents an attempt to develop a thermodynamically consistent model of the entire solidification process on physical grounds."

Jan 1, 1986

Designing rigging systems for complex castings has been more of an art than a science. Foundrymen have used thumb rules based on past experience to develop working designs. Of late, attempts are being made to formalize the procedure through the use of rule based expert systems, process modeling and other tools. Designing risers is one of the challenges of the rigging system design. Once the riser location have been determined, an optimization technique coupled with a casting simulation code can be used to determine the optimum riser dimensions. The main drawback of using a finite element or a finite difference based process simulation code along with the optimization routine is that the computation time involved is too large. Such an approach, thus, is unrealistic for practical situations where different options have to be explored and conclusions drawn in a short period of time. This difficulty has been avoided in the present work. The optimization scheme has been coupled with a modulus based solution routine to optimize the riser dimensions. The modulus calculations provide a good and quick estimate of the freezing time at different points in the casting. A functional, obtained from these freezing time values, is minimized by altering the dimensions of the riser until an optimum shape is obtained. Some examples have been included to illustrate the utility of this technique.

Jan 1, 1994

By Seshadri Seetharuman

The present paper summarises a series of measurements of the interaction parameter of oxygen in liquid copper with respect to a third element, e(M)o, where M is Mn, Zn, As, Se or Te which are common impurities in the liquid metal. The technique employed was the solid electrolyte galvanic cell method. The cell used may be represented as Pt, W or cermet / Cu-O-M // ZrO2 - CaO // AO, A /PT where AO/A represents a suitable oxide/metal reference. The measurements indicate that Mn and Zn interact very strongly with oxygen in liquid copper while, in the case of arsenic the interaction parameter is nearly zero. The behaviour of the elements Se and Te is unique with respect to oxygen interactions in copper bath. At oxygen levels, xo= 10-4 ? 10-5, the apparent interaction parameters are negative, comparable to that for sulphur. On the other hand, at lower oxygen levels, the results indicate that the interaction parameter values are positive. The results are discussed in the light of some of the theoretical models for solute interactions in liquid metals.

Jan 1, 1993

By Takeo Fujino, Nobuaki Sato, Junichi Hasegawa, Masato Nakazawa, Kohta Yamada

"Tantalum oxide thin films were deposited on quartz substrates by laser ablation of Ta2O5 target using Nd:YAG pulse laser. Deposition-was observed when a laser light energy higher than 200 mJ and its repetition rate higher than 3 Hz. A thin film of 0.1 µm thickness was obtained by the ablation using a laser light of 300 mJ and 6 Hz for 2 sec. The thickness of the film increased with increasing energy, repetition rate and irradiation time of laser. By the SEM observation, it was found that many island-like particles were deposited on quartz substrate forming a thin film. The obtained thin film, which was identified as ? Ta-O by X-ray diffraction, was oxidized to Ta2O5 by the heat treatment in air at I273 K for 3 h.IntroductionTransition metal oxides have a potential to show special characteristics in electrical, magnetic and/or optical properties. When such compounds are fabricated in the form of thin film, the special properties would be improved or new characters would appear in comparison with bulk materials. Tantalum penta-oxide is widely used as a capacitor since Ta2O5 shows high dielectric constants up to high temperatures. The tantalum solid capacitor has been fabricated by the electrical oxidation of sintered Ta metal cylinder followed by MnO2 film coating. However, further improvements, reduction and layered structure formation, are required for compacting the devices. The layered structure of thin films would be applicable for the above requirements. The formation ofTa2O5 film by low pressure CVD1), photo CVD2) and magnetron sputtering3l were reported. The laser ablation -method is one of the most convenient techniques for the deposition of thin films from their compounds, such as oxides. Formation of Ta2O5 film by pulse laser deposition (PLD) method using ArF excimer4), Nd:YAG (533nm)5) and TEA CO2 6 lasers was reported. In these PLD studies, ablation was carried out in relatively high oxygen pressures resulting in formation of Ta2O 5 film. In this paper, the deposition of tantalum oxide thin film by the laser ablation of Ta2O 5 using Nd:YAG pulse laser was examined at a viliety oxygen pressures ranging from 10-8 to 10 Torr. The morphology of the films was also investigated in relation with substrate temperature and oxygen pressure."

Jan 1, 2000

By J. Chen Kuriyama

One method to store hydrogen effectively involves the use of metal complexes such as the alkali-element aluminum hydrides. The hydriding/dehydriding properties of these materials depend on how to prepare them with different structures and microstructures. The present work focused on a high-energy ball milling technique to produce Ti-doped lithium tetrahydridoaluminate (LiA1H4) and lithium hexahydroalanate (Li3AIH6) powders with nanocrystallites. The phase structures and dehydriding/rehydriding characteristics were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller measurement, thermogravimetry, and differential scanning calorimetry. The mechanism of dehydrogenation and rehydrogenation was also examined by means of X-ray photoelectron spectroscopy (XPS). The results on the relation between the reversible hydrogen storage and catalysis function of the Ti-doped complex hydride indicate that both the homogenous distribution of Ti+AI nanoclusters and the Ti¬catalyst with Ti e> Ti3+ (Ti0/Ti2+/Ti3+) defect sites play important roles in optimizing the reversible hydrogen storage.

Jan 1, 2002

By D. Neuschiltz, M. Witthaut, R. Cremer

"Metastable (Ti,Al)N coatings with fee structure have been shown to exhibit superior performance as compared to TiN under conditions of wear at elevated temperatures due to their better oxidation resistance and hardness. The oxidation resistance of these coatings increases significantly with increasing Al-content. However, the deposition of (Ti,Al)N films with Ti/ Al ratios below about 30/70 leads to a hexagonal structure which is not suitable for tribological coatings. Only little is known about the location of the cubic to hexagonal phase transition and hence about the optimum composition of (Ti,Al)N hard coatings.To determine the position of this transition, Tii-xAlxN films with different Ti/Al ratios were deposited on high speed steel at substrate temperatures between 100 and 700 °C by means of reactive MSIP. The composition of the films was determined by electron probe microanalysis (EPMA) and X-ray photoelectron spectroscopy (XPS), the crystallographic structure by thin film X-ray diffraction (XRD).It could be shown that in case of deposition temperatures of 300-700 °C a two-phase region exists in the metastable TiN-AlN phase diagram, which expands with increasing temperature, wheras at 100 °C substrate temperature no two-phase region was observed. But in opposition to the phase diagram known from literature, which is based on thermodynamic estimations, the detected two-phase region is narrow for typical PVD temperatures, thus allowing the deposition of cubic single-phase Al-rich (Ti,Al)N hardcoatings for tribological applications. Based on these results, a new Ti1-xAlxN film with x = 0.62 has been developed, which showed an increase of oxidation resistance by a factor of 4."

Jan 1, 1998

By George A. Calboreanu

In order to overcome drilling and tapping of high hardness wear resistent material in slurry pumps, most of time mild steel inserts are mounted in the mold and after pouring they become an integrated part of the casting. This process is limiting the size and design possibilities of slurry pumps and efforts were made to drill and tap the hard iron itself. The paper will present practical results obtained in drilling and tapping Cr-Mo wear resistent material with hardness in excess of 700 HBN. The life time of the slurry pump parts used in hazardous waste fuel transportation with high slurry velocity and 15% solid loading some of it being quartz, increased 2.5 to 6 times.

Jan 1, 1996

By Shufeng Yang, Anping Dong, Yongfeng Chen, Jingshe Li, Lifeng Zhang, Liyuan Sun

"Instead of nickel-based stainless steel, a nitrogen-bearing stainless steel was produced to reduce the production cost stemming from the shortage of nickel recourses. Thermodynamic model to calculate the saturation nitrogen content in the stainless steel were developed and the model was validated by experimental measurement. The experiments were performed with a high temperature induction furnace. Nitrogen gas under constant pressure was injected into the crucible with a top lance by which the nitrogen was transferred to the molten stainless steel. The effects of chemical composition, temperature, superficial active elements and nitrogen-flow rate on transferring nitrogen to the steel were investigated and discussed.IntroductionWith the rapid production growth of stainless steels, nitrogen-bearing stainless steel has recently attracted more and more attention for their high strength and excellent corrosion resistance imparted by interstitial nitrogen without decreasing its toughness and ductility. Moreover, the addition of nitrogen to the stainless steel as a substitute for nickel leads a lower consumption of nickel, so significantly lowers the high production cost stemming from the shortage of nickel recourses. However, production of the nitrogen-bearing steel is difficult since nitrogen is a gas element and has a low solubility in the steel. So efficiently increasing the amount of nitrogen in steel continues to be one of the main concerns for the production of nitrogen-bearing steels.Currently there are some special processes to produce austenitic stainless steels with a very high N content, including pressurized electroslag remelting, counter-pressure casting, special induction melting and powder metallurgy, etc [1]. Special expensive vacuum system was required for these processes. Alloying nitrogen at a normal pressure can be performed by alloy addition or gas injection. Blowing nitrogen gas is a more economic and advisable method since the nitrogen-bearing alloy is quite expensive and contains high content of impurities. A number of investigations have been reported on the solubility of nitrogen gas in pure iron [2] but few in iron-based multi-component alloys such as stainless steel.In the current study, the effects of steel chemical composition, temperature, superficial active elements and nitrogen-flow rate on transferring nitrogen to the steel were experimentally investigated with a high temperature induction furnace."

Jan 1, 2011

By Claude Lorenson

"The Spyrometer™ imaging pyrometer brings new dimension of imaging capabilities to temperature measurement technology by combining a high temperature video camera with scanning optical pyrometry. This gives the operators the ability to observe process conditions while measuring the temperature of virtually any object or region in the field of view. Since the lens tube of the camera can be air or water cooled, it is possible to see inside furnaces giving a very good view of many different types of metallurgical processes. Specific benefits in process knowledge and maintenance tasks for furnaces in different types of metal industries are discussed.1-Principles of Imaging PyrometryLens tube, camera and processorImaging pyrometry is the combination of video imaging and computer-driven pyrometry that measures the temperature of certain zones (selected by the operator) within the image viewed on the monitor screen. To obtain a detailed image of the metallurgical process under observance, it is necessary to place the optical objective of the camera close to the process. The Spyrometer™ (which is Quadtek's tradename for its imaging pyrometer) objective is housed in a lens tube that is cooled and permits insertion inside the vessel of interest. The length of the lens tube is chosen on the basis of making sure that the tip of the tube is just beyond the refractories lining the inside of the furnace. In most pyrometallurgical processes, we have found that the most reliable system set-up uses a water cooled shroud to cool the lens tube optics. A sapphire window provides maximum protection from the environment. Even in the case of the water cooled version, there is an air purge for the lens that keeps the objective clean and protects against hot metal splashes."

Jan 1, 1997

By Ying Mao, Zhancheng Guo, Long Ma, Huiqing Tang

"A new 2D computational fluid dynamic (CFD) model was developed for the gaseous reduction of iron ore fines in an innovative reactor-multilayer moving-fluidized bed. The solution of the proposed model was performed by integration of FLUENT and PHOENICS. Numerical results of cold state were compared with the experimental data and the agreement between them was good. A hot case-gaseous reduction of iron ore fines using syngas with this reactor was simulated using the present CFD mode. Results indicate that under the given simulation conditions, total pressure drop is 90 Pa less than that under cold state though the gas supply rate is increased about 4m3 under hot state. Gas temperature decreases from 1073 K at the bottom to 500 K at the top, Utilization efficiency of the gas reduction potential is about 27 %. For ore fines reduction, the final reduction fraction could reach 0. 70 and solid temperature 900 K.IntroductionWith the development of coal gasification technology, various coals could be converted to Syngas with air or steam. Therefore gaseous reduction of iron ore fmes becomes an acceptable alternative process for iron making besides blast furnace route[!] and moreover it still has some advantages in processing low grade iron ore fines[2]. Gaseous reduction using fluidized bed technologies is the most competitive in all direct reduction iron-making processes up to now. It has the advantage that ore fines can be directly charged to the process without prior treatment while its disadvantages are particle agglomeration and high gas/solid ratio[3]. To avoid these advantages, a new reactor, multilayer moving-fluidized bed reactor has been developed for carrying out the gaseous reduction. Hydrodynamic behaviors of gas and fines in the reactor were studied and the results were satisfying[4]. However, due to its unique structure of the multilayer moving-fluidized bed and unique gas-solid flow pattern, models of multiphase flow as IPSA, DPM and Eulerian Model could not give a satisfying solution. The current paper is developed a new CFD model and a new solution approach for simulation of the reactive gas-solid flow in the multilayer moving-fluidized bed for its optimization, design improvement and future scale-up."

Jan 1, 2013

By Yuanyuan Wang, Hong Li, Xueting Liu, Hao Bai, Kang Zhou

"Phase change materials are widely used in efficient utilization of energy and new energy technology. Especially, more attention has been paid to composite phase material, which is applied on architectural energy-saving and efficient working fluid. In this paper, stearic acid-silicon dioxide composite material was prepared by sol-gel process from tetraethyl orthosilicate (TEOS) and stearic acid (SA). The material was investigated by Field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR) and Differential scanning calorimeter (DSC). The FE-SEM results show that 3D-grids of silicon dioxide were formed clearly and SA was encapsulated in the silicon dioxide shell. The FT-IR results show that there were no chemical reactions between silicon dioxide and SA, which is the chemical property of the composite material, is stable. The DSC results show that the composite phase change material has favorable heat capacity. This material is expected to be used to make a cooling working fluid.1. IntroductionEnergy thermal storage becomes increasingly prominent issue in recent years, because thermal storage has been used in many aspects, for example, it can be added into building materials to improve heat conditioning. Another potential application of thermal storage materials is that the intermittent waste heat can be collected and recycled effectively by using the thermal storage facility. Thus, energy thermal storage plays a significant role in conserving available energy and improving its utilization [1]. Energy thermal storage includes sensible heat storage and latent heat storage. The latent heat storage has great heat density with a constant temperature during the phase change process [2-5]. Large quantities of latent heat storage will be absorbed and released when phase change takes place. Based on the former researches, some phase change material (PCM), such as fatty acid and paraffin waxes, has been proved to have high latent heat storage capacity and appropriate thermal properties [5-6]. However, using the PCM in energy storage systems directly is restricted, e.g. some properties of organic PCM, like form-stability and thermal conductivity, are not good enough to use. Meanwhile, almost all the inorganic PCMs are corrosive and most materials may cause sub cooling and segregation [7-9].The other problem is that the leakage when the temperature reaches the phase change point. Therefore, encapsulated composite phase change material (CPCM) emerged in order to solve the problem of leaking out, minimize the sub cooling and prevent phase segregation. [10-13] However, the easy flammability of fatty acid also has hindered the development of PCM. Accordingly, it has been found out that silicon compounds are environmentally friendly promising substitutes for halogen-containing flame retardants. Especially, silsesquioxanes are excellent in the flame retardancy. So CPCM can be encapsulated with SiO2 acting supporting material."

Jan 1, 2014

By Kan Song, Lin Liu, Hengzhi Fu, Jun Zhang, Haijun Su, Xiaojiao Jia

"Al2O3/YAG/ZrO2 eutectic in situ composite has been regarded as new generation of high temperature structural material due to its excellent performance even close to its melting point. The directionally solidified Al2O3/YAG/ZrO2 eutectic ceramics are prepared by recently developed Laser Floating Zone Melting (LFZM) apparatus in which a splitter mirror is used to obtain two beams with the same quality from one CO2 laser. With the two laser beams irradiate the sample from opposite directions, the sample is zone melted. The apparatus configuration and the solidification processing are described in detail. The solid/liquid interface morphology is studied and the mechanism of microstructure formation especially the characteristic of eutectic cellular is discussed. It is shown that YAG and ZrO2 phases play a leading role during the ternary eutectic growth. Meanwhile, the relationship between the solidification microstructure and the processing parameters are investigated.IntroductionAl2O3/YAG/ZrO2 ternary eutectic in situ composite, due to its excellent high temperature mechanical properties, is now considered to be a promising candidate material as a replacement of nickel based super alloy for new generation aero space engine turbine blade [1]. They exhibit flexural strength of 360-500 MPa from room temperature to 2073K in air atmosphere [2]. The compression creep strength at 1873K is 433MPa with the strain rate of 104/s [3]. However, because of the high melting point and complex physical properties, there remain still many difficulties for its application. One of the bottlenecks is the poor understanding of the relationship between microstructure and solidification conditions."

Jan 1, 2012