Ni-Cr合金真空钎焊金刚石界面微结构分析

钎焊单层超硬磨料砂轮极高的结合强度和接近理想的锋利形貌 ,使它在生产应用中显示出传统砂轮无法比拟的优异性能。这种新型超硬磨料砂轮以其卓越的磨削性能必将逐步取代传统单层电镀砂轮。本文在真空炉中用钎焊的方法 ,用Ni Cr合金钎料 ,适当控制钎焊温度、保温时间和冷却速度 ,实现了金刚石与钢基体的高强度连接。并用深腐蚀的方法处理钎焊后的试样 ,用扫描电镜、X 射线能谱仪 ,结合X 射线衍射结构分析 ,对金刚石与钎料界面微区结构进行了分析。结果表明 :在钎焊过程中 ,钎料会在金刚石界面形成富铬层并与金刚石表面的C元素反应生成Cr7C3 和Cr3 C2 ,其中Cr7C3 呈笋状生长 ,Cr3 C2 呈片状生长。Ni Cr合金与金刚石的冶金结合 ,是实现金刚石和钢基体有高结合强度的主要因素。最后通过磨削对比实验确证了金刚石与钎料有较高的结合强度

On the Microstructure of the Interface Between Ni-Cr Filler and Diamond

The monolayer brazing diamond grinding tool possesses strong intensity and ideal appearance, which shows distinct advantages over traditional tools. It will replace the traditional electroplated grinding wheel in the future due to its excellent grindability. In this paper, vacuum furnace brazing was carried out by using Ni Cr alloys as braze filler metals. Proper brazing temperature and heat preservation time can realize strong bonding between diamond and steel substrate. After the brazing sample is deep etched, SEM and EDS were applied to analyze the interface between Ni Cr alloys and diamond. Results showed that the Ni Cr alloys reacted with C in the diamond surface to form carbide soon after the Ni Cr alloys was melted. The Cr 3 C 2 distribute as flake in the diamond surface, and the Cr 7 C 3 distribute as needle like in the top of Cr 3 C 2 . X ray diffraction revealed that the wetting and bonding behavior on the diamond surface was realized through Cr 7 C 3 which was produced by interaction between Cr atoms of Ni Cr alloy and C atoms of the diamond surface at elevated temperature. Finally, grinding tests show that the wear modes of such a brazed grinding wheel were mainly grit fracture and attrition rather than grit dislodgment from the bond.