化学镀法制备Si₃N₄—Co复合纳米粉末新技术研究

【作者】 张慧泽；

【导师】 郦剑；

【作者基本信息】 浙江大学 ， 材料学， 2003， 硕士

【摘要】 本文以常温化学镀法制备高质量的纳米氮化硅—钴磷复合粉末为目标，研究镀液组分及其工艺参数对纳米氮化硅超声波化学镀钴的影响规律，得到了纳米氮化硅超声波化学镀的优化配方，制得了镀层均匀，分散性好的纳米复合粉末。完成的主要工作如下： 通过在纳米氮化硅的活化及化学镀反应过程中施加超声波，实现纳米氮化硅的常温化学镀，解决纳米粉末分散性的问题。 用高分辨电镜观察复合粉体的形貌，进行电子衍射分析；用D/3AX 3B型X射线衍射仪作复合粉体的物相分析；用PV9900型能谱仪作复合粉末的成分分析。 通过对比实验，分别就镀液组分及其工艺参数对纳米氮化硅化学镀钴反应孕育期、反应速度、复合粉末外观、形貌，镀层成份及相结构的影响规律进行了深入研究。 孕育期是反映化学镀液质量，影响化学镀效率的重要参数。硫酸钴和次亚磷酸钠浓度的增加，镀液的PH值升高，装载量的增大，反应的孕育期变短； 镀速是反应时间与增重综合作用的结果。实验表明：镀液PH值和施镀温度升高，次亚磷酸钠和缓冲剂浓度增加，镀速提高。硫酸钴浓度增加，镀速增加，浓度30g/l时有最大值。络合剂在浓度较低时对化学镀有加速作用，浓度太高反而会延缓镀速。 镀液的PH值与次亚磷酸钠和硫酸钴的摩尔比对镀层成分、及相结构的影响较为显著。镀液PH值升高，镀层磷含量减少，形成非晶镀层的趋势增大。次亚磷酸钠与硫酸钴的摩尔比I增大，镀层磷含量增加，形成非晶态镀层的趋势增加。 PH值在9.5～11.0之间，镀液稳定性好，所得复合粉末镀覆均匀，磁性较好。硫酸钴浓度18～40g/l，次亚磷酸钠浓度20～40g/l，可以得到镀覆均匀、分散性好的复合粉末；增加其浓度，复合粉体的镀覆质量得以提高。使用酒石酸钾钠作络合剂时，其浓度在120～135g/l范围内，使用柠檬酸钠作络合剂时，其浓度在40～65之间，可以得到镀覆均匀、分散性好的复合粉末。装载量在1～10g/l之间，可以实现纳米氮化硅粉末的完全包覆，得到镀覆均匀、分散性较好的复合粉末。装载量小，复合粉体金属钻磷合金的含量高，镀层厚：装载量大，复合粉体中的金属钻磷合金的含量低，镀层薄。 预处理过程对化学镀的影响较大，活化效果好，研磨较细，较干燥的施镀粉木，反应孕育期短，镀速快，镀覆质量好。 通过综合考虑镀液稳定性和复合粉末的质量，在上述对比实验的基础上，筛选优化配方，得出了纳米氨化硅常温化学镀的优化配方，经TEM、XRD、EDX分析，表明所得复合粉末粒径均匀，分散性高，镀层质量好。更多还原

【Abstract】 The objective of the paper is to get nano SisN^Co composite powder of high quality by electroless plating at normal temperature. The rules were researched that the composition of electroless plating solution and reaction condition had an influence on the reaction of electroless plating of nano-Si3N4 with ultrasonic wave. The best composition of electroless plating solution was obtained. Mostly tasks as follows:It was realized that electroless cobalt plating of nano-Sis^ at normal temperature with ultrasonic wave. The problem of dispersion of the nano-powder was solved.The morphologies of powder were observed by using high-resolution transmission electron microscopy(HRTEM); X-ray diffraction (XRD) pattern was used to analyze the phases of the powder; Energy dispersive X-ray spectroscopy(EDX) was used to analyze the component of composite powder.Through parallel experiments, the rules were studied more that the composition of electroless plating solution and reaction condition affected on the reaction of electroless cobalt plating of nano-SiaN4 with ultrasonic wave, such as " induction period", the speed of reaction, appearance and morphology of composite powder, the component and phases of the plating et al."induction period" was reflected the quality of electroless plating solution ,and affected the efficiency of electroless plating, "induction period" was shortened with the increase of the concentration of NaH2?O2 ?I-hO and CoSO4. It was shortened by increasing the PH and the loading of powder.The speed of electroless plating was the result of the added weight divided by the "plating time". The experiments showed that these factors could increase the plating rate which the concentration of NaH2?O2 ’t^O, the PH and the temperature of electroless plating had been risen. The speed of electroless plating was increased with the increase of concentration of CoSCU. When the concentration of CoSC>4 was 30g/l, the plating rate was max. With the increasing of KNaC4H4O6 * 4H2O and NaaCeHsO? ?2H2O, the speed of plating was increasing when the concentration of them was low. However, when the concentration of them was enough higher, theinif.plating rate was decreasing.Phosphorus was more in composite powder with the decreasing of the PH of solution, it is also more when the concentration of Nal-^POa ?I-bO is increased. If Phosphorus was adequacy in composite powder, Co-P alloy coating becomes non-crystalline.The quality of composite powder was better, and the stabilization of solution is improved with the increase of the PH from 9.5 to 11.0. The cladding of composite powder was of higher uniformity and dispersion with the increase of the concentration of NaH2P02 ?H20(20~40g/l) and CoS04(18~40g/l).When the bath loading is lower than 10g/l , the metal covered was full and composite powder was thin and disperse well. The Co-P alloy coating of powder was more and thickness of plate was incrassate with the decreasing of the loading.When the nano-Si3N4 was thinner and drier, and the effect of activation was better, the speed of plating was increased and "induction period" was shortened.The best composition of electroless plating solution and reaction condition was optimized by comparison experiment. The composite power was analyzed by EDX , XRD , TEM. The result indicated that the cladding of composite powder was of high uniformity and dispersion .更多还原