【摘要】 本文研究了Si3N4-Ni系结合剂掺杂合成的PcBN的维氏硬度、抗弯强度、磨耗比、抗冲击韧性、车削性能与结合剂以及各掺杂物相对含量等的关系。采用金相显微镜、扫描电镜和X射线衍射仪等仪器设备对PcBN试样进行了微观组织结构和物相分析。分析表明,添加镍粉可有效提高PcBN的硬度和耐磨性,PcBN的烧结情况良好;结合剂对cBN高温润湿情况良好;有新的物相生成。氮化硅的存在添加镀镍氮化硅晶须使PcBN的抗冲击韧性和抗弯强度得到提高;被加工工件的表面粗糙度达到了0.8μm。更多还原

【Abstract】 In this paper,the micro hardness,bending strength,abrasion ratio,impact resistance and turning performances of PcBN with Si3N4-Ni binder were studied.The effect of the composite binder and the dopant content on such properties were discussed.The microstructure and phase composition of PcBN were investigated by scanning electron microscope(SEM) and X-ray diffraction(XRD).The results showed that,cBN grits were well wetted by the composite binder under high temperature;the sintering of PcBN was in good condition;formations of a number of new phases were observed.The presence of Si3Ni4 effectively improved the performances of PcBN.The Si3Ni4 whiskers,especially Ni-coated Si3Ni4 whiskers,increased the impact resistance and bending strength of PcBN.The best surface roughness of workpiece machined with the above PcBN turning tool attained 0.8 μm.更多还原