金刚石表面镀层在磨具中的作用机理

Effect mechanism of diamond surface coating in diamond tools

采用湿法镀（化学镀、电镀）或真空镀（蒸发镀、溅射镀、离子镀）方法，在金刚石表面镀覆一层铜、镍、钛、钼、钨等金属，或者它们的复合镀层。表面镀覆已经与单晶合成、分选、聚晶烧结、气相沉积一起，成为金刚石多品种专用化发展的五条重要途径之一。镀层赋予金刚石所需要的各种特有的物理化学性能，不仅可以提高金刚石颗粒强度以及与结合剂的结合强度，还有对金刚石表面的宏观隔离保护作用和对金刚石结构的微观侧面支撑作用．从而有利于防止金刚石在使用过程中被氧化和石墨化。特别是在树脂结合剂磨具中，镀层的热导率介于金刚石和树脂之间，可以有效地减缓磨削热脉冲对树脂造成的热损伤，从而显著延长其耐用度，使树脂磨具的使用寿命提高50％-100％。

Coating metal such as Cu, Ni ,Ti, Mo, W or compound coating on diamond grain （DG）surface by coating（ chemical, electronic plating） and vacuum plating method （ evaporating, sputtering, ionization） was studied. Surface coating, together with synthesizing, sorting, polycrystallization and CVD sedimentation, constitute the five main means to promote multi diversity and specialpurpose of diamond. Surface coating can improve the physical and chemical property of DG including strength, binding strength, surface isolation and micro structure supporting, which prevent diamond from graphitization and oxidization. When used for resin bond grinding wheels, coating can decrease heat damage because its thermal conductivity is between diamond and resin, and can increase the tool life by 50% - 100%.