超硬材料刀具研究现状和趋势

RESEARCH STATUS AND DEVELOPING TENDENCY OF SUPER-HARD MATERIALS CUTTER

切削工具的制造面临着工业上被加工材料材质变化的挑战。随着现代机械加工朝着高精度、高速切削、硬加工代研磨、干加工保护环境和降低成本等方向发展 ,对刀具性能提出了相当高的要求。开发各种耐磨性优良的能长时间进行稳定加工的超硬材料是必然的发展趋势。就现阶段而言 ,超硬切削工具材料主要是指以金刚石 /立方氮化硼构成的材料。金刚石是自然界最硬的物质 ,具有极高的弹性模量 ,最高的热传导率和最低的摩擦系数 ,是机械加工高硅铝合金、碳化硅颗粒 /纤维增强金属基复合材料等耐磨蚀材料的理想工具材料。立方氮化硼与金刚石一样 ,在工业上用十分相似的条件合成制得 ,具有极高的硬度。作为切削工具材料 ,立方氮化硼的一个重要特点是在极高的温度下与钢件接触的稳定性 ,在同样的条件下金刚石可能会发生溶解并转化成石墨。因此 。

Higher demand has been put forward to the properties of cutting materials along with the developing of modern machining industry toward the direction of high precision?high speed cutting?the replacement of grinding by hard machining(HRC40～70)?dry machining(no coolant)for protecting environment and decreasing costs and so on.The cutter materials are facing with a serious choose.It is an inevitable tendency to developing various super-hard cutting materials with high wear-resistance and ability of long time stable machining.At the present stage?super-hard cutting tool materials are mainly consisted of diamond or cubic boron nitride(CBN). Diamond is the hardest substance in nature.It has extremely high Young's modulus?the highest thermal conductivity?the lowest friction coefficient.Therefore diamond is an ideal tool material to machine wear-corrosion parts such as high Si/Al alloy?SiC particle or fiber reinforced metal basic composite materials etc.Just as diamond,CBN is manufactured in industry at extremely similar high-temperature and high-pressure conditions.As cutting material?an obvious advantage of CBN is the stability when it contacts with steel work-piece in high temperature,however,the diamond will dissolve and transform into graphite in same conditions.Therefore CBN tool materials are also an object that has being developed and studied very hard in recent ten years.