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为了进一步提高钎焊金刚石工具的使用性能,采用添加3%、5%Ni/C的Ni-Cr合金在保护气氛炉制备钎焊金刚石试样,钎焊温度为1 050℃,保温5 min;利用扫描电镜对钎焊后金刚石形貌和钎焊层组织进行分析,用维氏硬度仪测试钎焊层硬度。结果表明:添加Ni/C的Ni-Cr合金对金刚石具有较好的润湿性,能实现钎焊层对金刚石的高强度连接;碳化物在金刚石表面形核长大,与金刚石具有一定的位向关系;Cr7C3的形貌为空心,钎焊层中形成簇状共晶石墨,都与添加的Ni/C有关;钎焊层中残存有少量Ni/C,钎焊层硬度由820HV0.2降低至700HV0.2,有利于降低金刚石钎焊后热应力和提高磨粒后期出露。
In order to further improve the serviceability of brazed diamond tools, brazing diamond samples were prepared by using Ni-Cr alloy with 3% Ni / C and 5% Ni / C in a brazing atmosphere furnace at a brazing temperature of 1050 ℃ for 5 min. Scanning electron microscope (SEM) was used to analyze the diamond morphology and braze structure after brazing. The brazing hardness was measured by Vickers hardness tester. The results show that the Ni-Cr alloy with Ni / C has good wettability to diamond and can achieve the high strength connection of the brazing layer to the diamond. The carbides grow on the surface of the diamond and have a certain bit with the diamond To the relationship; Cr7C3 hollow, brazing layer formation of eutectic graphite, are added Ni / C; brazing layer remaining a small amount of Ni / C, brazing layer hardness decreased by 820HV0.2 To 700HV0.2, is conducive to reducing the thermal stress after diamond brazing and improve the late grain exposed.