SiC颗粒表面金属化工艺及显微组织分析

为改善碳化硅颗粒与金属的润湿性,本文研究了在碳化硅颗粒表面金属化即沉积Ni-P层的工艺方法.首先采用表面清洁处理,继而采用粗化和活化敏化工艺对平均尺寸为5μm的Si C颗粒进行预处理,实现了在化学镀镍前在碳化硅表面产生微小的缺陷,并吸附Pd作为催化活性物质,为后序化学镀过程Ni-P的吸附、形核、长大提供了有利条件.利用正交试验方法,结合增重百分率和镍元素的相对含量等指标,研究了化学镀液的成分对镀层组织及形貌的影响.研究发现,当化学镀液中Ni~(2+)]浓度为0.25 mol/L、NH_4~+]浓度为0.6 mol/L,Ni~(2+)]/H_2PO_2~-]浓度之比为0.4、柠檬酸浓度为0.1 mol/L及pH为10,温度为45℃时,SiC颗粒表面完全包覆Ni-P.通过比较实验可知,预处理中活化敏化过程对后续Ni-P合金的包覆有重要促进作用.同时,化学镀液各成分中对施镀效果的影响顺序为:溶液中Ni~(2+)]浓度pH柠檬酸三钠的含量温度Ni~(2+)]/H_2PO_2~-]浓度之比NH_4~+]浓度.

Surface metallization process and microstructure analysis of SiC particles

To improve the wettability between SiC particles and metal, this study took the deposition of Ni-P alloy on the surface of SiC particles. Electroless plating Ni-P alloy on the surface of SiC particles is a kind of excellent surface treatment technology in many industrial sectors. The acid and alkali washing, coarsening, activating and sensitizing were used successively to pretreat the SiC particles of 5 μm, resulting in producing some small defects on the surface of the SiC particles, and adsorbing Pd atom, providing a favorable condition of Ni-P alloy adsorption, nucleation and growth. Experimental studies were performed on the compositions of electroless plating for the influence of the microstructure and the morphology of coating by the orthogonal test analysis. Connecting with weight percentage and the relative content of nickel element, the optimal process conditions are as follows:Ni2+] of 0.25 mol/L, NH4+] of 0.6 mol/L, the ratio of Ni2+] and H2PO2-] of 0.4, citric acid of 0.1 mol/L, pH of 10 and temperature of 45 ℃. From the SEM analysis, SiC particles surface is fully coated with Ni-P alloy. Activating and sensitizing contribute to Ni-P alloy coating. Primary and secondary sequence of parameters is Ni2+] , pH, citric acid, temperature, the ratio of Ni2+] and H2PO2-] and NH4+].