石墨自润滑钎焊cBN砂轮节块界面微观结构

Interfacial microstructure of graphite self-lubrication brazed cBN wheel segments

通过添加石墨制作了自润滑钎焊cBN砂轮节块。采用三点抗弯试验测试节块的抗弯强度,并运用扫描电镜、能谱仪对节块断面形貌和结合界面的元素扩散进行了分析。结果表明:添加质量分数5%石墨的钎焊cBN砂轮节块抗弯强度达到116 MPa;cBN与Cu-Sn-Ti钎料在界面化学结合,提高了钎料对磨粒的把持力,实现了对cBN磨粒的牢固联接;节块中的石墨保持原有的层状结构,可保证磨削过程润滑膜的形成;在节块内部分布着很多孔隙,可为砂轮提供充足的容屑空间。

Brazed cBN wheel segments were fabricated based on graphite self-lubricating effect. Bending strength of the wheel segments were measured by three-point bending experiments. Bonding interface and fracture morphology of the wheel segments were detected using scanning electron microscope （SEM） and energy dispersion spectrometer （EDS）. The results show that the bending strength of the wheel segments with mass fraction 5 % graphite reaches 116 MPa. The metallurgical bonding at the interfacial zone between cBN and Cu- Sn-Ti filler increases the holding strength of filler to the grains. The graphite shows the original lamellar structure, which can potentially form a lubricating film during grinding. Some irregularly holes are formed in the segments, which ensures sufficient storage space for chips during grinding.