脉冲电流烧结技术的研究进展

脉冲电流烧结（Ｐｕｌｓｅ ｅｌｅｃｔｒｉｃ ｃｕｒｒｅｎｔ ｓｉｎｔｅｒｉｎｇ，ＰＥＣＳ）是材料科学领域开发出的一种新型快速烧结技术，已广泛应用于金属与合金、结构陶瓷、氧化物超时体、复合材料、热电材料、离电材料、高分子材料以及功能梯度材料的制备；检验结果，对脉冲电流烧结非导电性粉体的烧结过程和机理，提出自己的观点。     

An Analysis Method for Capability Reliability of a Thermal System

ＡｎＡｎａｌｙｓｉｓＭｅｔｈｏｄｆｏｒＣａｐａｂｉｌｉｔｙＲｅｌｉａｂｉｌｉｔｙｏｆａＴｈｅｒｍａｌＳｙｓｔｅｍＪｉｎＪｉａｓｈａｎＷａｎｇＳｈａｏｍｉｎｇＣａｉＱｉＮａｖａｌＡｃａｄａｍｙｏｆＥｎｇｉｎｅｒｉｎｇＷｕｈａｎ４３００３３，Ｐ．Ｒ．Ｃｈ...     

GdSe涂层(CdSe/Ni)的烧结工艺对半导体隔膜电极(SnO_2·P/CdSe/Ni)性能的影响

通过Ｘ射线衍射（ＸＲＤ）、扫描电子显微镜（ＳＥＭ）、透射电子显微镜（ＴＥＭ）和高能电子衍射（ＲＨＥＥＤ）等技术，研究了由蒸发冷凝法制备的ｎ型半导体材料ＧｄＳｅ超细微粒涂层（ＣｄＳｅ／Ｎｉ）的烧结工艺。实验指出，烧结后的ＧｄＳｅ粉体涂层的结晶形态、膜层的致密均匀性以及结晶粒度的尺寸等均与烧结的工艺条件密切相关。将涂在Ｎｉ箔上的ＧｄＳｅ粉体膜层置于氩气氛中，在缓慢升降温的条件下，于４５０～５００℃温度下恒温２ｈ的多次重复烧结，可以获得表面平整致密、在衬底Ｎｉ箔上附着力强的ＧｄＳｅ多晶膜层，以下称ＣｄＳｅ／Ｎｉ为烧结体。将烧结体应用于半导体隔膜电极（（ＳｎＯ２·Ｐ／ＣｄＳｅ／Ｎｉ）中，可有效地改善半导体隔膜电化学伏打电池（ＳＣ－ＳＥＰ电池）的光电化学特性。     

Study on the Methods of Equipment Maintenance Management

ＳｔｕｄｙｏｎｔｈｅＭｅｔｈｏｄｓｏｆＥｑｕｉｐｍｅｎｔＭａｉｎｔｅｎａｎｃｅＭａｎａｇｅｍｅｎｔＧａｏＰｅｎｇｘｉａｎｇＱｉｎｇｄａｏＵｎｉｖｅｒｓｉｔｙＱｉｎｇｄａｏ２６６０７１，Ｐ．Ｒ．ＣｈｉｎａＡｂｓｔｒａｃｔＴｈｉｓｔｈｅｓｉｓｄｉｓｃｕｓ...     

快速烧结制备纳米Y-TZP材料

研究了快速热压烧结和放电等离子快速烧结（ＳＰＳ）制备纳米Ｙ－ＴＺＰ材料．利用快速热压烧结和 ＳＰＳ快速烧结,可在烧结温度为 １２００℃、保温９～１０ｍｉｎ条件下,制得相对密度超过９９％的 Ｙ－ＴＺＰ材料．研究发现：虽然快速热压烧结和 ＳＰＳ烧结都可使Ｙ－ＴＺＰ在相同温度下的密度高于普通热压烧结,但两种快速烧结所得Ｙ－ＴＺＰ的晶粒都大于无压烧结所得;另外,快速热压烧结所得样品的结构不够均匀,而ＳＰＳ烧结的样品的均匀性较好．文章对产生这些现象的原因进行了理论探讨．     

Introduction of IJPEM

ＡＩＭＳＡＮＤＳＣＯＰＥＴｈｅＩｎｔｅｒｎａｔｉｏｎａｌＪｏｕｒｎａｌｏｆＰｌａｎｔＥｎｇｉｎｅｒｉｎｇａｎｄＭａｎａｇｅｍｅｎｔ（ＩＪＰＥＭ）ｉｓａｎｅｗｊｏｕｒｎａｌｐｕｂｌｉｓｈｅｄｂｙｔｈｅＮｏｒｔｈｗｅｓｔｅｒｎＰｏｌｙｔｅｃｈｎｉｃａｌＵ...     

CA SELECTS Carbon ＆ Graphite Fibers

ＣＡＳＥＬＥＣＴＳＣａｒｂｏｎ＆ＧｒａｐｈｉｔｅＦｉｂｅｒｓＩＳＳＵＥ２０１２１：１３５８８５ａ纤维增强酚醛树脂复合材料的制备Ｈｏｊｏ，Ｊａｔｓｕｏ；，Ｙｏｓｈｉｎａｇａｅｔｃ．ＪＰ０６，１００，７０６（９４，１００，７０６）标题复合材料具有高的树脂...     

Introduction of IJPEM

ＩｎｔｒｏｄｕｃｔｉｏｎｏｆＩＪＰＥＭＡＩＭＳＡＮＤＳＣＯＰＥｈｅＩｎｔｅｒｎａｔｉｏｎａｌＪｏｕｒｎａｌｏｆＰｌａｎｔＥｎｇｉｎｅｅｒｉｎｇａｎｄＭａｎａｇｅｍｅｎｔ（ＩＪＰＥＭ）ｉｓａｎｅｗｊｏｕｒｎａｌｐｕｂｌｉｓｈｅｄｂｙｔｈｅＮｏｒｔｈｗｅ...     

Introduction of IJPEM

ＩｎｔｒｏｄｕｃｔｉｏｎｏｆＩＪＰＥＭＡＩＭＳＡＮＤＳＣＯＰＥｈｅＩｎｔｅｒｎａｔｉｏｎａｌＪｏｕｒｎａｌｏｆＰｌａｎｔＥｎｇｉｎｅｒｉｎｇａｎｄＭａｎａｇｅｍｅｎｔ（ＩＪＰＥＭ）ｉｓａｎｅｗｊｏｕｒｎａｌｐｕｂｌｉｓｈｅｄｂｙｔｈｅＮｏｒｔｈｗｅｓ...     

Introduction of IJPEM

ＩｎｔｒｏｄｕｃｔｉｏｎｏｆＩＪＰＥＭＡＩＭＳＡＮＤＳＣＯＰＥＴｈｅＩｎｔｅｒｎａｔｉｏｎａｌＪｏｕｒｎａｌｏｆＰｌａｎｔＥｎｇｉｎｅｒｉｎｇａｎｄＭａｎａｇｅｍｅｎｔ（ＩＪＰＥＭ）ｉｓａｎｅｗｊｏｕｒｎａｌｐｕｂｌｉｓｈｅｄｂｙｔｈｅＮｏｒｔｈｗ...     

Electric Current-Assisted Sintering of 8YSZ: A Comparative Study of Ultrafast High-Temperature Sintering and Flash Sintering

Electric current-assisted sintering (ECAS) is a promising powder consolidation technique that can achieve short-term sintering with high heating rates. Currently, main methods of performing ECAS are indirect heating of the powder compact in a conductive tool or direct heating with current flowing through the powder compact. Various influencing factors have been identified to explain the rapid densification during ECAS, such as ultrahigh heating rates, extra-high temperatures, and electric field. However, the key consolidation-enhancing factor is still under debate. This study aims at understanding the role of heating rate on the enhanced densification during ECAS of 8 mol% Y₂O₃-stabilized ZrO₂ (8YSZ) by experimental and numerical methods. Two different heating modes, ultrafast high-temperature sintering (UHS, indirect heating) and flash sintering (FS, direct heating), are studied. The novel UHS technique is successfully applied to consolidate the 8YSZ samples. Additionally, finite element methods (FEM) combined with a constitutive model is adopted to predict the densification and grain growth. Furthermore, a comparison of UHS and FS is performed to investigate the thermal effect (heating rate) and athermal effect (electric field) individually. The results indicate that the high heating rate is the key factor of the rapid densification during UHS and FS of 8YSZ.     

Pulse electric current sintering of hydroxyapatite/β-tricalcium phosphate composites

Hydroxyapatite (HA)/β-tricalcium phosphate (β-TCP) composites attract attentions as bone implant materials. As one of the fabrication method of HA/β-TCP is mixing of HA and β-TCP powder in advance of sintering. This method enables to control the ratio of content of β-TCP easier. However, it is difficult to obtain dense composites. In this study, we focused on pulse electric current sintering (PECS) to obtain dense HA/β-TCP composites. The sinterability is evaluated with relative density and grain size measurements. Composition of sintered body was also characterized by X-ray diffraction. In comparison with pressureless sintering, PECS increased relative density of the composites without grain growth. In HA/β-TCP sintered by PECS, the phase transformation from β-TCP to α-TCP was promoted. This is due to higher thermal energy by spark discharge during PECS. On the other hand, sintering additives (MgO) inhibited phase transformation. It was suggested that sinterability of HA/β-TCP composites was improved by PECS.     

Thermo-mechanical stability of porous alumina: effect of sintering parameters

Recently, we proposed a two-step heating schedule involving pulse electric current sintering (PECS), a kind of pressure assisted vacuum sintering, and subsequent post-heat treatment in air to fabricate porous alumina support, using commercially available alumina and carbon powders [J. Mater. Res. 18 (2003) 751]. During pressure assisted vacuum sintering, Al₂O₃–C system of low porosity was obtained and in second stage, i.e. during post-heat treatment in air, carbon particles present in the Al₂O₃–C system burnt out to form highly porous Al₂O₃ support. Following our previous brief study, the effects of sintering parameters such as temperature, pressure, and heating rate on the properties of the porous alumina were investigated. The porosity varied between 28 and 38% depending on the sintering parameters. As desired, the pore size distribution did not change with post-heat treatment temperature and hence the mechanical properties as well. It was concurred from this present study that the sintering parameters of PECS greatly influenced pore characteristics and other properties of porous compacts. We admit that the initial composition ratio of powder mixture (Al₂O₃:C) also plays important role on properties such as porosity, pore size, etc. which is beyond the scope of this present study.     

Sintering,thermal stability and mechanical properties of ZrO2-WC composites obtained by pulsed electric current sintering

ZrO₂-WC composites exhibit comparable mechanical properties as traditional WC-Co materials, which provides an opportunity to partially replace WC-Co for some applications. In this study, 2 mol.% Y₂O₃ stabilized ZrO₂ composites with 40 vol.% WC were consolidated in the 1150°C–1850°C range under a pressure of 60 MPa by pulsed electric current sintering (PECS). The densification behavior, microstructure and phase constitution of the composites were investigated to clarify the role of the sintering temperature on the grain growth, mechanical properties and thermal stability of ZrO₂ and WC components. Analysis results indicated that the composites sintered at 1350°C and 1450°C exhibited the highest tetragonal ZrO₂ phase transformability, maximum toughness, and hardness and an optimal flexural strength. Chemical reaction of ZrO₂ and C, originating from the graphite die, was detected in the composite PECS for 20 min at 1850°C in vacuum.     

用放电等离子技术烧结TiB2陶瓷

利用脉冲大电流快速烧结技术（也称放电等离子烧结SPS技术）研究了TiB2的烧结过程。结果表明：升温速率对烧结样品的相对密度、晶粒尺寸及烧结过程中真空室气压均有重要影响。最佳的升温速率使TiB2烧结晶粒相对最小、烧结体相对密度较高。分析认为，在SPS条件下的快速升温有利于颗粒表面活化，烧结体晶粒尺寸既受控于烧结时间，也受控于晶粒生长活化能。     

快速致密化制备SiCp/Fe复合材料及其性能研究

研究了一种电流直加热动态热压快速致密化工艺,采用此工艺克服了粉末冶金法和铸造法的局限性,快速制备了10vol%SiCp/Fe复合材料,考察了材料在不同烧结电压和不同烧结时间情况下的致密化行为及其力学性能,结果表明此工艺制备的10vol%SiCp/Fe复合材料,相对密度达到99.6%,布氏硬度为477HB,抗拉强度为912MPa,显微组织细小均匀.     

Densification of pure magnesium by spark plasma sintering-discussion of sintering mechanism

In this study, high-quantity pure magnesium was prepared by SPS, and the sintering densification mechanism was discussed by using numerical simulation and simultaneous experiment. Results show that a layer of dense magnesium oxide was formed at the surface of Mg particles, and the oxide reduction can be observed owing to the effect of oxide film removal in SPS. The high energy pulsed current flows preferentially through particle contact surfaces, which provides the conditions for the generation of micro-arc between particles and the temperature at the particles contact point can be up to 1979 °C. With the low pressure at the initial sintering stage, local high temperature induced by micro-arc makes the melting (even evaporation) appearance. At the same sintering temperature of 570 °C, the obvious difference in bending strength also demonstrates the significance of spark discharge in SPS. The formation process of sintering neck demonstrates that sintering process is the reflection of melting (even evaporation), diffusion and plastic deformation. In order to realize tiny area and high-quality connection between powder particles, an innovative powder sintering technology using high-frequency pulse electric current (High frequency pulse current assisted sintering) is proposed based on the enlightenment of the skin, proximity and arc discharge effect of high-frequency pulse current. This technology is also instructive for other alloys and engineering materials.     

A review on selective laser sintering/melting (SLS/SLM) of aluminium alloy powders: Processing,microstructure, and properties

Manufacturing businesses aiming to deliver their new customised products more quickly and gain more consumer markets for their products will increasingly employ selective laser sintering/melting (SLS/SLM) for fabricating high quality, low cost, repeatable, and reliable aluminium alloy powdered parts for automotive, aerospace, and aircraft applications. However, aluminium powder is known to be uniquely bedevilled with the tenacious surface oxide film which is difficult to avoid during SLS/SLM processing. The tenacity of the surface oxide film inhibits metallurgical bonding across the layers during SLS/SLM processing and this consequently leads to initiation of spheroidisation by Marangoni convection. Due to the paucity of publications on SLS/SLM processing of aluminium alloy powders, we review the current state of research and progress from different perspectives of the SLS/SLM, powder metallurgy (P/M) sintering, and pulsed electric current sintering (PECS) of ferrous, non-ferrous alloys, and composite powders as well as laser welding of aluminium alloys in order to provide a basis for follow-on-research that leads to the development of high productivity, SLS/SLM processing of aluminium alloy powders. Moreover, both P/M sintering and PECS of aluminium alloys are evaluated and related to the SLS process with a view to gaining useful insights especially in the aspects of liquid phase sintering (LPS) of aluminium alloys; application of LPS to SLS process; alloying effect in disrupting the surface oxide film of aluminium alloys; and designing of aluminium alloy suitable for the SLS/SLM process. Thereafter, SLS/SLM parameters, powder properties, and different types of lasers with their effects on the processing and densification of aluminium alloys are considered. The microstructure and metallurgical defects associated with SLS/SLM processed parts are also elucidated by highlighting the mechanism of their formation, the main influencing factors, and the remedial measures. Mechanical properties such as hardness, tensile, and fatigue strength of SLS/SLM processed parts are reported. The final part of this paper summarises findings from this review and outlines the trend for future research in the SLS/SLM processing of aluminium alloy powders.     

Y-α/β-sialon的气压烧结

研究了Ｓｉ３Ｎ４粉末粒度分析发现相组成,ＡｌＮ粉末的粒度及分阶段烧工艺对气压烧结α／βｓｉａｌｏｎ的致密化,产物相组成和力学性能的影响,采用三阶段保温烧结（１７００℃,１ｈ,１８００℃,１ｈ及１９５０℃,１５ｈ）减少了Ｓｉ３Ｎ４与液相在高温反应促进了材料致密,适当的烧结工艺下及用适当的埋粉,细ＡｌＮ原料有利于材料致密。细Ｓｉ３Ｎ４原料（０．３μｍ）中氧杂质增加导致复合材料中α－ｓｉａｌｏｎｓ相减少     

氧化物陶瓷闪烧机理及其应用研究进展

闪烧是近些年广受关注的一种电场辅助烧结技术。本文介绍了闪烧的起源与发展, 并对闪烧的基本特征进行了分析。在闪烧孕育与引发过程的研究方面, 发现了孕育阶段的非线性电导特征和电化学黑化现象, 提出了氧空位主导的缺陷机制; 在闪烧阶段的快速致密化研究方面, 提出了电场作用导致的缺陷产生和运动会在粉体颗粒间产生库仑力, 有利于烧结前期的致密化过程, 同时发现闪烧致密化过程中还伴随着金属阳离子的快速运动; 在闪烧阶段的晶粒生长和微结构演变方面, 发现了试样温度沿电流方向呈非对称分布, 试样中间位置的晶界迁移率明显提高, 提出电化学缺陷对微观结构有重大影响。基于上述研究成果, 本团队利用电场作用下出现的低温快速传质现象, 发展了陶瓷闪焊技术, 实现了同种陶瓷/陶瓷、陶瓷/金属, 甚至异种陶瓷/陶瓷之间的快速连接; 发展了陶瓷闪烧合成技术, 不仅实现了典型氧化物陶瓷的快速合成, 而且实现了高熵陶瓷和具有共晶形貌的氧化物陶瓷的快速合成; 发展了氧化物陶瓷的电塑性成形技术, 初步实现了氧化锆陶瓷低温低应力下的快速拉伸和弯曲变形。本文最后总结了闪烧机理研究面临的挑战, 并从焦耳热效应和非焦耳热效应两方面展望了闪烧的发展方向, 期望对闪烧技术在国内的发展有所裨益。