Si_3N_4陶瓷表面镀锆的融盐热析出反应研究

Study of Zirconium Coating on Si_3N_4 Ceramic Surface by Molten Salt Reaction

研究了Si_3N_4陶瓷表面镀锆的融盐热析出反应,以X射线衍射仪分析了镀膜物相,以电镜(SEM)对镀件进行了显微观察。结果表明:(1)镀膜的单位面积沉积量随反应温度的升高以及反应时间的延长而增加;镀膜的单位面积沉积速率随反应温度的升高而增加,随反应时间的延长而减小;单位面积镀膜增重随K_2ZrF_6初始浓度的逐渐增大,先呈上升趋势,达到最大值后又逐渐下降,K_2ZrF_6初始质量分数为60％时,单位面积镀膜增重最大;(2)镀膜物相为ZrN,Zr_5Si_3,Zr_3O;(3)镀膜表面光滑,是银白色金属光泽;膜层与Si_3N_4陶瓷基体结合紧密;镀膜为层状结构,界面结构为Si_3N_4/ZrN/Zr_5Si_3/Zr_3O;Zr_5Si_3晶粒粗大,ZrN晶粒细小,Zr_3O呈不均匀地附着在Zr_5Si_3的表面;(4)单位面积增重(△W/△S)与t_(1/2)呈良好的直线关系;(5)反应活化能约为126kJ/mol。

The Mechanism of zirconium coating on Si_3N_4 ceramic surface by molten salt reaction has been studied. The phase of the coating film was analyzed by X-ray diffraction. The sample was observed by SEM. The results show that aggradation of plating film on the per surface area increases as rising the reaction temperature,prolonging the reaction time; aggradation velocity of plating film on the per surface area increase as rising the reactive temperature, it decrease as prolonging the reaction time. The weight gain on the per surface area increases,until reach it's maximum, it will decrease as K_2ZrF_6 initial concentration rising, when initial concentration is 60wt%, the weight gain on the per surface area reaching it's maximum. The composition of the coating film includes ZrN, Zr_5Si_3, Zr_3O, Which are smooth, with silver luster;film layer closely united with Si_3N_4 ceramic;film is layer form. The form of interface is Si_3N_4/ZrN/Zr_5Si_3/Zr_3O; crystal grain of Zr_5Si_3 are not small, ZrN are small, Zr_3O not even clings to surface oF Zr_5Si_3. △W/△S-t^(1/2) shows linearly relationship. The activation energy is about 126 kJ/mol.