Characteristics of sintering processes

Conclusions New, more accurate formulations of the autonomy and stress transfer principles are proposed. Quantitative characteristics of autonomy are defined. An examination is made of characteristics determining quantitatively the participation of various types of deformation (with contact fixation or disturbance) in consolidation (sintering, sintering under pressure, shaping) and characteristics determining the degree of localization of deformation. These characteristics can be expressed in the form of various functions of the paramter — the fraction of the volume of particles displaced as a result of flow of the material of a critical zone. The possibility of determining certain characteristics by experiment is demonstrated.Translated from Poroshkovaya Metallurgiya, No. 3(183), pp. 12–18, March, 1978.     

Interfacial reaction and mass transport of the components in the Al2O3-TiN system during sintering

Conclusions Results of x-ray phase analyses have shown that Al₂O₃-TiN composites produced by nitrogen and vacuum heat treatment and hot pressing retain a two-phase structure at temperatures of up to 2300°K. The changes exhibited by the Al₂O₃ and TiN lattice parameters may be indicative of oxidation and subsequent dissolution of the resultant titanium oxides both in alumina and in titanium nitride. The extent of this reaction depends on the method and conditions of heat treatment.Translated from Poroshkovaya Metallurgiya, No. 11(275), pp. 32–38, November, 1985.     

Theory and technology of sintering processes,thermal and thermochemical treatment reaction kinetics for interaction of tungsten with copper-zirconium melts

We investigated the growth kinetics of layers of W₂Zr phase on tungsten interacting with copper-silicon melts at 1150°C. We determined the limiting value of the zirconium content in the copper melt (40.1 at. %). Below this value, we do not observe the indicated layer. We discuss the mechanism of reactive diffusion in the system and the effect of zirconium additives on the liquid phase sintering of the copper-tungsten materials. We have discovered well-defined differences between the growth rates of the layers on polycrystalline and single-crystal specimens of tungsten.Institute of Problems in Materials Science, National Academy of Sciences of Ukraine. Kiev. Translated from Poroshkovaya Metallurgiya. Nos. 3–4(384). pp. 25–29. March–April 1996. Original article submitted October 25, 1994.     

Consolidation processes in the sintering of fine-grained iron-copper pseudo-alloys

The properties of fine-grained iron-copper pseudo-alloys (ICPA) and consolidation processes that occur during their sintering are studied. The grains are no larger than 0.5 μm. It was established that the specimens undergo shrinkage, not growth, when fine iron-copper mixtures are sintered within the range 600–1130 °C. This occurs as a result of active consolidation of the dispersed powder mixture, shortening of the diffusion paths, and the active formation of solid solutions based on iron and copper. Sintered ICPAs have a stable fine-grained microstructure with a maximum grain size of 0.5 μm only when they are sintered and treated in the solid phase. A coarse-grained structure is formed when ICPAs are heated to temperatures at which a liquid phase appears. Fine-grained ICPAs are also characterized by high hardness (up to 240–260 HB). Translated from Poroshkovaya Metallurgiya, Nos. 1–2(411), pp. 22–29, January–February, 2000.     

放电等离子烧结制备铁基大块非晶材料

以惰性气体雾化的非晶铁基粉末为原料,采用放电等离子烧结技术(SPS)制备大块非晶材料.探索了SPS烧结温度对烧结体的物相、相对密度、微观结构和性能的影响.试验表明,采用优化的SPS烧结工艺,用粉末冶金的方法,可以获得致密的大块非晶材料,部分性能与铸态相当.     

Carburization processes during the sintering of iron-graphite materials

Summary The authors investigated the effect of the oxide content of iron powder on the microstructure and strength characteristics of sintered iron+3% graphite material. It was found that raising the oxide content of the iron powder in the charge results in the formation of abnormal hypereutectic structures and a sharp fall in the compressive strength of the material.Some decrease in the structural abnormality of sintered iron-graphite material prepared from iron powder with a high (2% or more) oxide content is attained by decreasing the duration of sintering and increasing the cooling rate of the sintered material.The use of iron powder with a total Fe content of less than 98% in not recommended.Paper to the Fifth Republican Scientific-Technical Conference on Powder Metallurgy, Kiev, March 29–31, 1966.Translated from Poroshkovaya Metallurgiya, No. 1(49), pp. 14–19, January, 1967.     

注射成形纯钛脱粘和烧结工艺研究

粉末注射成形是制造复杂形状钛及钛合金零件的合适工艺。本文利用氢化脱氢（HDH）钛粉制备注射成形纯钛材料，研究了溶剂脱粘、热脱粘和真空烧结工艺对粘结剂脱除率、烧结显微组织和力学性能的影响。结果表明：溶剂脱粘的适宜温度为50～60℃，4h后可以脱除97％以上的可溶性粘结剂；在随后的真空热脱粘过程中，在200-450℃高温阶段降低升温速率、延长保温时间，有利于脱除剩余聚合物粘结剂；真空烧结温度为1250℃时，烧结致密度可高达98％，但表层易形成硬质TiC相和微量TiO2相；在该温度下烧结1．5h，制品抗拉强度和伸长率分别提高到349MPa和6．4％，继续延长烧结时间会导致拉伸性能下降。     

Effect of manganese on sintering processes in the Ti-Fe system

Conclusions The behavior of Ti-Fe-Mn specimens under conditions of sintering at temperatures above the eutectic point is analogous to that of Ti-Fe and Ti-Fe-Ni specimens: The changes in the linear dimensions of compacts and the magnitude of exothermic effects depend on the rate of heating to the sintering temperature. At high rates of heating the linear dimensions of Ti-Fe-Mn specimens change in a stepwise manner (their shrinkage decreases). During slow heating a decrease in the shrinkage of Ti-Fe-Mn specimens, unlike that of Ti-Fe and Ti-Fe-Ni specimens, is followed by its increase.Translated from Poroshkovaya Metallurgiya, No. 1(277), pp. 15–18, January, 1986.     

烧结热过程质量和能量平衡的诊断及分析

基于质量和能量守恒原理,对宝山钢铁股份有限公司不锈钢分公司2号烧结机进行了详细的质量和能量平衡测试.通过对测试结果的分析,全面了解本烧结机的质量和能量收支水平.在此基础上对烧结系统的热利用情况进行了研究,并将测试结果与宝山钢铁股份有限公司宝钢分公司3号烧结机的热利用情况进行了对比分析,对影响能耗的问题进行了探讨,提出了相应的改进建议.本次测试的原始数据为今后的节能技术改造提供了重要的参考依据.