AgCuTi合金钎焊单层立方氮化硼砂轮

为研制我国新一代单层钎焊CBN(立方氮化硼 )磨料砂轮 ,尝试Ni-Cr和Ag -Cu-Ti两种活性钎料 ,在真空炉中钎焊。试验结果表明 ,Ni-Cr合金钎料对CBN磨料不浸润 ,钎焊后CBN磨料全部脱落 ;而Ag -Cu -Ti合金钎料对CBN则表现出良好的浸润性并将CBN牢牢钎焊住。借助扫描电镜、X射线能谱和X射线衍射对界面微区组织的分析研究表明 ,钎焊过程中Ag -Cu -Ti合金钎料中的Ti向CBN磨料界面富集 ,并与CBN磨料表面的N和B元素反应生成TiN和TiB ,这是实现Ag -Cu -Ti合金钎料与CBN磨料高结合强度的关键因素。断口形貌的分析研究表明 ,CBN与Ag -Cu -Ti合金钎料间的断口发生在Ag -Cu -Ti合金钎料层 ,说明CBN磨料与Ag -Cu -Ti合金钎料的结合强度已超过了Ag-Cu -Ti合金钎料本身强度。最后将研制出的单层钎焊CBN磨料砂轮与传统电镀CBN砂轮进行了重负荷磨削对比试验 ,钎焊砂轮表现出明显的优势

Brazing of Single Layer Cubic Boron Nitride Wheel with AgCuTi Alloy Under Vacuum Atmosphere

In order to develop new generation monolayer brazing CBN (cubic boron nitride) grinding wheels, two types of active filler alloys (Ni Cr and Ag Cu Ti) were tested in vacuum furnace. The results show that a Ni Cr alloy fails to wet and bond CBN grits ,while a Ag Cu Ti alloy exhibits good wetting and bonding towards CBN grits. SEM EDS microanalyses have shown that during brazing Ti in Ag Cu Ti alloy segregated preferentially to the surface of the CBN to form a Ti rich reaction product. X ray diffraction reveals that the wetting and bonding behaviour on CBN surface by Ag Cu Ti alloy melt are realized through TiN and TiB which are produced by interaction between Ti atoms of Ag Cu Ti alloy and N or B atoms of CBN surface at elevated temperatures. The rupture occurs in Ag Cu Ti alloy layer. It can be considered that chemical metallurgic bonding has formed in the interface between CBN grits and Ag Cu Ti alloy. Finally a monolayer brazing CBN grinding wheel with regular abrasive distribution was put forward to try a grinding test. The experimental results show distinct advantages over conventional electroplated CBN grinding wheel.