低温烧结氮化铝陶瓷烧结助剂的研究进展

分析烧结助剂在低温烧结制备高热导率AlN陶瓷过程中的作用和机理;综述AlN低温烧结助剂的研究实践;介绍烧结助剂的选择原则和几种不同烧结助剂体系对AlN陶瓷材料的烧结致密度与热导率的影响.     

BN含量对注射成形AlN-BN复相陶瓷性能和组织的影响

采用粉末注射成形和无压烧结相结合的工艺制备AlN-BN复相陶瓷,讨论了AlN-BN混合料的流变性能以及BN含量对复相陶瓷热导率、硬度以及显微组织的影响.研究结果表明,AlN-BN混合料具有良好的流动性和较小的温度敏感性,适宜陶瓷注射成形.复相陶瓷的热导率、致密度以及硬度随着BN含量增加而降低,主要是由于BN本身具有较低的硬度和热导率以及在烧结过程中形成特殊的卡片房式结构阻碍了AlN烧结致密化造成的.综合考虑热导率和可加工性能的要求,最佳的BN质量分数在10%~15%之间,所制备的复相陶瓷的热导率大于120W·m^-1·K^-1,硬度低于HRA80,致密度大于90%.     

Effect of Y2O3 and Dy2O3 on Microstructure and Mechanical Behaviors of Aluminum Nitride Ceramics

The effects of two types of additives, Y2O3 and Dy2O3, on the sintering and mechanical behaviors of AlN ceramics were investigated. The experimental results show that the sintering temperature can be decreased and the mechanical behavior can be improved by adding rare earth in AlN ceramics. The strength of AlN ceramics with Y2O3 and Dy2O3 are 326 and 320 MPa, respectively, which are 97.6% and 93.9% higher than the un-doped AlN ceramics. The fracture behavior on the fracture surfaces of rare earth oxide AlN ceramics was found to be a mixed mode of transgranular fracture and intergranular fracture. As a result, it is concluded that the improvement of bending strength of AlN ceramics with Y2O3 and Dy2O3 addition are mainly achieved by strengthening the grain boundary.     

高导热氮化铝陶瓷的粉末注射成形技术

氮化铝(AlN)陶瓷具有热导率高、热膨胀系数低、电阻率高等特性以及良好的力学性能,被认为是新一代高性能陶瓷基片和封装的首选材料,为了满足微电子技术发展对微型复杂形状高导热陶瓷零部件用量日益增加的需求,该文作者研究利用粉末注射成形技术制备高导热AlN陶瓷零部件.该技术以AlN粉末为原料,加入5%Y2O3为烧结助剂;选用蜡基粘结剂体系(PW+PP+SA),确定粉末装载量为62%(体积分数),注射温度为160～170℃,注射压力为90～100 MPa;采用溶剂脱脂+热脱脂工艺脱脂;在1850℃流动氮气氛中烧结.所制备出的AIN陶瓷热导率达232.4 W/(m·K).     

Effect of prior heat treatment for commercial-grade aluminum nitride powder in gas atmospheres and activating additions on the structure and properties of hot-pressed ceramics based on it

The effect of carbon-containing additions and prior heat treatment in hydrogen and nitrogen for commercialgrade AlN powder on the chemical composition, structure, and also some physicomechanical properties of hot-pressed ceramics based on it are studied. It is shown that hot pressing occurs mainly in the solid phase. The fracture mechanism for hot-pressed ceramics varies from intercrystalline (using unprocessed AlN powder) to predominantly transcrystalline, the grain size of the basic phase decreases, and thermal conductivity and strength parameters increase. Translated from Poroshkovaya Metallurgiya, Nos. 5–6(413), pp. 100–107, May–June, 2000.     

高热导率氮化铝陶瓷制备技术进展

作者详细介绍了高热导率氨化铝陶瓷制备工艺的研究状况,包括粉末的合咸、成形、烧结3个过程.指出低成本的粉末制备工艺和氨化铝陶瓷的近净成形技术是很有价值的研究方向.     

Effects of Behaviors of Aluminum Nitride Ceramics with Rare Earth Oxide Additives

The effects of three types of additives, Y₂O₃, Nd₂O₃ and Er₂O₃ on the behaviors of AlN ceramics were investigated. The experimental results showed that the sintering temperature could be decreased and the mechanical behavior could be improved by adding rare earth oxide in AlN ceramics. The highest strength and fracture toughness of AlN ceramics with 2% Y₂O₃ addition were 311 MPa and 3.5 MPa·m^1/2, respectively. Second phase of AlN ceramics with Y₂O₃ addition was identified as Y₃Al₅O₁₂ formed by the reaction with Al₂O₃, meanwhile that with Nd₂O₃ was identified as NdAlO₃. The fracture behavior of AlN ceramics with Y₂O₃ and Nd₂O₃ were a mixed mode of transgranular fracture and intergranular fracture. Because of the high evaporation rates of Er₂O₃ (1.2 × 10⁻⁵ g·cm⁻²), no aluminium erbium oxide was found in the AlN ceramics doped with Er₂O₃. So the dielectric loss tanger(tanδ) and thermal conductivity of AlN ceramics doped with Er₂O₃ were best.     

W波段用BeO-TiO2衰减瓷研究

以氧化铍、二氧化钛为原料,通过还原气氛烧结制备出BeO-TiO2衰减瓷,采用扫描电镜、矢量网络分析仪及闪射法导热仪等检测仪器,研究了BeO-TiO2衰减瓷的微观形貌及在W波段(75～ 110 GHz)的微波衰减性能和导热性能.     

AlN-W复合陶瓷的微波损耗研究

以AlN和W粉为原料,采用放电等离子烧结技术,在1 400～1 700℃、30MPa的工艺条件下制备了AlN-W复合陶瓷.采用扫描电镜、能谱分析仪、安捷伦精密阻抗分析仪4284A等对复合陶瓷的微观组织、介电常数、微波损耗进行了表征,研究了影响复合陶瓷微波损耗性能的因素.结果表明,AlN粉末颗粒细小、烧结保温时间增加,有...     

纳米AlN颗粒弥散增强铜基复合材料的制备及性能研究

本文采用高能球磨结合放电等离子烧结法制备了含不同质量分数AlN的AlN/Cu复合材料。研究了AlN质量分数对AlN/Cu复合材料微观形貌、相对密度、显微维氏硬度、拉伸强度、延伸率及导电性能的影响。结果表明:当AlN质量分数1.0%时,随着AlN质量分数的提高,复合材料的硬度、抗拉强度提高,断后伸长率、电导率降低。但当AlN质量分数为1.0%时,AlN/Cu复合材料相对密度为97.8%,显微硬度和抗拉强度分别达到了HV 119.5和259.7 MPa,电导率为49.30 mS·m~(-1),综合性能达到最优。     

Roles of rare earth oxide additives in millimeter-wave sintering of AlN

Roles of rare earth oxide (RE2O3) additives in millimeter-wave(MM) sintering of AlN were investigated from the standpoints of phase diagram, heating characteristics of rare earth oxides, and morphology of intergranular oxide phase. In the millimeter-wave sintering of AlN, densification temperature decreased with the decrease of the ionic radius of rare earth ion and was closely related with the eutectic temperature in the RE2O3-Al2O3 binary system. The lowest densification temperature in the millimeter-wave sintering of AlN with Yb2O3 additive was attributed to the largest heating rate of Yb2O3·Al2O3 binary oxide under millimeter-wave radiation. Furthermore, the lowest densification temperature could be attained while selecting the Yb2O3 content so as to form the intergranular phase with the eutectic composition in the Yb2O3-Al2O3 binary system. The result showed good agreement with the above mentioned during the sintering of Si3N4 with Yb2O3-Al2O3 additive. From TEM observation, it was verified that film-like intergranular oxide phase formed under millimeter-wave radiation was favorable for attaining high thermal conductivity in the Yb2O3 added AlNs.     

纳米AlN颗粒增强铜基复合材料的组织与性能研究

用粉末冶金法制备了AlN增强的Cu/AlN复合材料,研究了AlN含量对复合材料性能的影响和Cu/AlN复合材料的软化温度特性。结果表明,在烧结过程中,弥散分布在铜基体中的纳米AlN颗粒对致密化以及晶粒长大都有阻碍作用。随着复合材料中AlN颗粒质量分数的增加,材料的密度和导电性呈下降趋势,而硬度出现极大值。复合材料的软化温度达到700℃,远远高于纯铜的软化温度(150℃),从而提高了材料的热稳定性。     

Reaction synthesis of the Ti<Subscript>2</Subscript>AlN MAX-phase

The Ti₂AlN MAX-phase is synthesized by reaction sintering from Ti–AlN powder mixtures. The optimal synthesis mode of the compound containing less than 1% of the TiN impurity phase is established. It includes isothermal annealing at 1300°C for 2 h in argon at a pressure of 3 atm. The influence of the preliminary mechanical activation of the powder mixture and the reaction synthesis medium on the yield of the Ti₂AlN phase are investigated. It is shown that the activation leads to an increase in the content of the secondary TiN phase. It is revealed that the vacuum synthesis also does not make it possible to form the singlephase Ti₂AlN material.     

Roles of rare earth oxide additives in millimeter-wave sintering of AlN

Roles of rare earth oxide （RE2O3） additives in millimeter-wave（MM） sintering of AIN were investigated from the standpoints of phase diagram, heating characteristics of rare earth oxides, and morphology of intergranular oxide phase. In the millimeter-wave sintering of AIN, densification temperature decreased with the decrease of the ionic radius of rare earth ion and was closely related with the eutectic temperature in the RE2Oa-Al2O3 binary system. The lowest densification temperature in the millimeter-wave sintering of AIN with Yb2O3 additive was attributed to the largest heating rate of Yb2O3-Al2O3 binary oxide under millimeter-wave radiation. Furthermore, the lowest densification temperature could be attained while selecting the Yb2O3 content so as to form the intergranular phase with the eutectic composition in the Yb2O3-Al2O3 binary system. The result showed good agreement with the above mentioned during the sintering of Si3N4 with Yb2O3-Al2O3 additive. From TEM observation, it was verified that film-like intergranular oxide phase formed under millimeter-wave radiation was favorable for attaining high thermal conductivity in the Yb2O3 added AINs.     

Novel technique for synthesis and consolidation of aluminium nitride nanopowders

Abstract

In this paper, the use of a microwave plasma method for the synthesis of aluminium nitride nanopowders is described. The powders were consolidated to near theoretical densities using the unique rapid consolidation technique, plasma pressure consolidation (P²C), developed by MMI. Rapid consolidation of nanopowders is an ideal requirement for better mechanical and thermal properties in the consolidated part, as it retains the fine microstructure preventing anomalous grain growth. Microwave plasma synthesis resulted in aluminium nitride nanopowders (85–200 nm), which were consolidated to near theoretical density using P²C in <5 min without sintering additives. The effect of yttria (3 wt-%) as a sintering additive on the thermal conductivity (TC) of aluminium nitride was also evaluated and compared with TC values obtained from additive free AlN consolidated samples.     

涂层烧结状态对离心铸钢管表面质量的影响

对各种不同耐火填料组成的耐火涂层进行电镜扫描分析,研究了涂层烧结状况与铸管表面质量的关系,特别是对铸管表面气孔形成的机理进行了深入分析.结果表明耐火涂层的导热性、烧结温度、烧结速度和金属液的冷凝速度将直接影响气孔缺陷的产生.降低涂层的热传导性能、控制涂层的烧结程度可有效地避免铸管产生气孔缺陷.     

多元陶瓷增强Cu基复合材料的导热性能研究

以Cu基预合金粉为基体,加入SiC、Si_3N_4、B4C多元陶瓷作为颗粒增强相,利用粉末冶金法通过真空热压烧结工艺制备了SiC、Si_3N_4、B4C多元陶瓷/Cu基复合材料,并用激光脉冲法测试其室温条件下的导热性能。研究发现,随着SiC、Si_3N_4、B4C多元陶瓷含量的增加,复合材料的热导率逐渐减小,特别是当SiC、Si_3N_4、B4C多元陶瓷总质量分数大于15.0%以后,热导率急剧下降。复合材料内部的孔隙以及晶界、晶格畸变、位错等缺陷是影响热导率的主要因素。要获得导热性能良好的复合材料,应严格控制SiC、Si_3N_4、B4C多元陶瓷的质量分数在15.0%以内,并且可以考虑通过退火以及二次挤压等方法进一步提高致密度,减少烧结体内的位错、孔隙等缺陷,从而提高导热性能。     

煤矸石和用后耐火材料合成多孔堇青石

以煤矸石、用后滑板砖和用后镁碳砖为原料,采用石墨、淀粉和复合添加剂为造孔剂,制备出多孔堇青石材料,并研究造孔剂种类、造孔剂加入量和合成温度对材料合成和材料性能的影响.实验结果表明:采用煤矸石和用后耐火材料为原料,在1350～1400℃高温下可以合成高纯度的堇青石材料;复合添加剂为最佳造孔剂,其合适加入量为15%～25%;当复合添加剂加入量为20%,在1350℃保温3h条件下,合成材料的气孔分布均匀贯通,其显气孔率为44.9%,热膨胀系数为2.14×10^-6 K^-1,荷重软化点为1290℃,综合性能良好,具有优良的高温使用性能.     

Thermal conductivity of silicon carbide at high temperatures

Summary A study was made of the thermal conductivity of silicon carbide, produced by reactive sintering, over the range 200–1650°C. It is shown that the thermal conductivity of dense specimens increases with rise in temperature. The increase of thermal conductivity is caused by additional heat transfer due to radiation and to excitons.Translated from Poroshkovaya Metallurgiya, No. 2 (50), pp. 36–39, February, 1967.     

Mo—Cu合金的研究进展

Mo—Cu合金具有高的导热系数和低的线膨胀系数,被广泛应用于电触头材料、热沉材料、电子封装材料等。本文介绍了Mo—Cu合金的制备方法,以及提高Mo—Cu合金的致密化的方法,指出了Mo—Cu合金现在存在的问题及发展趋势。