放电等离子烧结聚晶立方氮化硼刀具的性能

采用溶胶凝胶法在立方氮化硼(cBN)表面包裹SiO2,以铝粉、碳化硼粉和炭粉为烧结助剂,利用放电等离子烧结(SPS)技术在压力100MPa和1 700℃保温10min的条件下制备聚晶立方氮化硼(PcBN),研究了PcBN的烧结性能、物相组成、微观形貌、力学性能以及所制备刀具的切削性能。结果表明:烧结助剂、原位反应和cBN颗粒活化等因素的共同作用促进了PcBN的致密化,其相对密度为97%;PcBN的主晶相为cBN,同时还存在SiO2、Al3BC3、SiC相;PcBN的硬度为(38±3.5)GPa,抗弯强度为(425±23)MPa;在相同切削速度下,所制备的PcBN刀具前刀面的崩损面积以及后刀面的磨损带长度均小于日本知名公司所产PcBN(BN11)刀具的,当切削速度由200m·min-1增加到400m·min-1时,所制备的PcBN刀具的磨损程度轻于BN11刀具的,PcBN刀具的切削性能优于BN11刀具的。

Properties of Polycrystalline Cubic Boron Nitride Prepared by Spark Plasma Sintering

Cubic boron nitride(cBN)was coated by SiO2 using the sol-gel method,and then polycrystalline cubic boron nitride(PcBN)was prepared by spark plasma sintering(SPS)under the pressure of 100 MPa at1 700℃for 10 min using Al powder,B4 C powder and carbon powder as sintering additives.The sintering ability,phase composition,micro-morphology,mechanical properties of PcBN and the cutting performance of fabricated cutter were studied.The results show that the combined effect of sintering additive,in-situ reaction and activation of cBN particles promoted the densification of PcBN,obtaining a relative density of 97%.The main crystalline phase of PcBN was cBN,and also included SiO2,Al3BC3 and SiC phases.The hardness of PcBN was(38±3.5)GPa,and bending strength was(425±23)MPa.At the same cutting speed,the breakdown area of the front surface and the wear band length of the rear surface of cutter made of the obtained PcBN were smaller than those of PcBN(BN11)cutter fabricated by a Japanes renowned company.When the cutting speed increased from 200m·min^-1 to 400m·min^-1,the wear degree of cutter made from PcBN was slighter than that of BN11 cutter,indicating the cutting performance of cutter made from PcBN prepared by SPS was better than that of BN11 cutter.