草酸盐共沉淀法制备金刚石金属结合剂

Preparation of diamond metal matrix by oxalate Co-precipitation method

以制备金刚石金属结合剂为目的,本文研究了用共沉淀法制备的含草酸亚铁、草酸铜和草酸镍为所需比例的三组分共沉淀作为金属结合剂前驱体,然后还原制得金属结合剂。研究了草酸盐共沉淀中的各组分的收率,确定了共沉淀的最佳反应条件：溶液浓度（Fe2＋）0.38 mol/L,反应温度50℃,反应时间1 h,氢氧化钠和草酸物质的量的比值为1-2：1。通过TPR和MS谱研究了共沉淀的分解还原过程及产物形态,研究发现,两者的加入能降低草酸亚铁的还原温度,共沉淀分解还原后生成合金粉末;对合金粉末进行了机械性能测定,结果表明：合金粉具有较好的硬度,比机械混合的结合剂提高20%以上,抗弯强度略有下降,但二者配合使用有较好的效果。

In order to prepare diamond metal matrix, in this study, tri-metal oxalate was used as the precursor of the metal matrix, which is composed of ferrous oxalate, nickel oxalate and cupric oxalate. The precursor was reduced to obtain the metal matrix. The conversion ratio of the Fe^2＋ ,Cu^2＋ and Ni^2＋ was studied by atomic absorption; the optimal reaction conditions for co-precipitation was determined as： Fe2. concentration0.3 mol/L, reaction temperature 50℃, reaction time 2 h, and optimum molar ratio of NaOH/H2 C2O4 =1 -2：1. The decomposition-reduction of co-precipitation was studied by TPR and Moesbauer spectrograph. The addition of nickel oxalate and cupric oxalate lowered the reduction temperature of ferrous oxalate. The Co-precipitate first decomposed into composite metal-oxide, and then the composite metal-oxide was reduced into alloy powder. Finally, the mechanical property of alloy powder was tested. The result shows that, the prepared alloy powder has higher degree of hardness, a 20% increase was observed compared with diamond metal matrix prepared by physical mixing; and the bend strength decreased slightly. Furthermore, we have observed that the combined use of the prepared alloy power with physically mixed diamond metal matrix provides improved overall performances.