原位反应制备Ag/TiB_2复合材料

Ag/TiB_2 Composite Prepared by In-Situ Synthesis Reaction

在Ti和B粉末原位反应生成TiB2条件热力学分析的基础上,采用机械合金化和粉末冶金原位合成工艺制备Ag/TiB2复合材料。采用Ag粉,Ti粉和B粉作为材料,按照Ti和B摩尔比1∶2占复合材料质量分数分别为0.5%,1.0%,3.0%和5.0%TiB2进行配料,混合后在自制高能球磨机上球磨60 h,转速为150 r.min-1,球料比为60∶1。球磨后的粉末在压力机上用模具冷压成型Φ21 mm×5 mm的块状试样,压力600 MPa,保压30 s。最后将混合粉末的压制体在900℃保温4 h热压炉中进行原位反应,并通入Ar气作为保护气氛,制备了不同TiB2含量的新型Ag/TiB2复合材料,系统研究了TiB2含量对AgTiB2触头复合材料组织和性能的影响。通过X-ray衍射仪,扫描电子显微镜(SEM)和能谱仪(EDS)表征分析了Ag/TiB2复合材料的相组成及显微组织,并采用维式硬度计和涡流电导仪对硬度和导电率进行了测试。研究结果表明,采用机械合金化球磨和原位反应粉末冶金技术制备Ag/TiB2复合材料是可行的。随着TiB2含量的增加,Ag/TiB2复合材料出现明显的TiB2团聚现象,且Ag/TiB2复合材料的硬度呈现先增大后减小的趋势,在硬度值为3%时,达到最大硬度值87.1HV,但Ag/TiB2复合材料电导率随着TiB2含量的增加逐渐下降。

On the basis of thermodynamics analysis of in-situ reaction between pure Ti powders and B powders,the in-situ TiB2 particle reinforced Ag/TiB2 composites were fabricated by mechanical alloying and powder metallurgy in-situ synthesis method.Ag,Ti and B powders were weighed according to the Ti/B molar ratio of 2∶ 1,and then were milled together in a self-made ball mill for 60 h,and the rotating velocity and the ball-to-powder ratio were 150 r·min-1 and 60/1,respectively.The milled powders were compacted into the specimens with a diameter of 21 mm and a length of 5 mm using a common mould stamping method on a press machine at the pressure of 600 MPa for 30 s,followed by in situ synthesis reaction in a hot press sintering furnace at 900 ℃ for 4 h under the protection of argon gas,and finally AgTiB2 composites with 0.5%,1.0%,3.0% and 5.0%TiB2 were prepared.The effect of TiB2 content on the microstructure and properties of Ag/TiB2 composite was studied,the phase constituent and microstructure of the milled Ag/TiB2 composite were characterized by a X-ray diffractometer,a scanning electron microscopy（SEM） equipped with an energy disperse spectroscopy（EDS）,and the hardness and electrical conductivity of the samples were tested by a Vickers hardmeter and an eddy current conductivity gauge,respectively.The results showed that it was feasible to fabricate Ag/TiB2 composite by mechanical alloying and powder metallurgy in-situ synthesis method.With the increase of TiB2 content,the obvious TiB2 aggregation occurs.The hardness of Ag/TiB2 composite increased at first and then decreased,and the composite had a peak hardness of 87.1 HV at 3%TiB2,while the electrical conductivity of Ag/TiB2 composite declined gradually.