AgCuTi合金钎焊单层立方氮化硼砂轮

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

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 。

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 characteristics 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 there is a test between monolayer brazing CBN grinding wheel and conventional electroplated CBN grinding wheel. The experimental results show distinct advantages over conventional electroplated CBN grinding wheel.