溶胶-凝胶法制备核壳结构MoSi_(2)@Al_(2)O_(3)颗粒及其形成机理  

MoSi_(2)@Al_(2)O_(3)Particles with Core-Shell Structure Prepared bySol-Gel Method and Its Formation Mechanism

作　　者：易周 崔世宇 罗军明[1] 初雨轩 YI Zhou;CUI Shiyu;LUO Junming;CHU Yuxuan(School of Materials Science and Technology,Nanchang Hangkong University,Nanchang 330063,China)

机构地区：[1]南昌航空大学材料科学与工程学院,南昌330063

出　　处：《材料导报》2023年第16期60-65,共6页Materials Reports

基　　金：国家自然科学基金(52104361)。

摘　　要：热应力和氧化生长层会导致热障涂层(TBCs)中微裂纹的萌生和扩展。MoSi_(2)被选为下一代自愈合因子,因为它改善了SiO2的流动性,并在高温下加速了内部裂缝的愈合。本研究采用溶胶-凝胶法实现MoSi_(2)@Al_(2)O_(3)核壳结构,可提高MoSi_(2)在氧化性气氛下的抗预氧化性能。选择异丙醇铝作为铝源,通过正交试验研究了温度、pH值和水铝比对增重的影响,得到了最佳参数。通过XRD、SEM、EDS和TEM方法分析了后处理的影响(包括相组成和微观结构)。结果表明,90℃、pH=4和水铝比200的组合是最佳参数。壳层增重最高可达22%。因为可以改变MoSi_(2)表面的Zeta电位,所以pH值在增重上占据主导地位。在真空炉中热处理3 h后,在1200℃下得到最大厚度(约200 nm)的α-Al_(2)O_(3)壳层。为避免MoSi_(2)的预氧化,后处理应在真空气氛中进行。Thermal stress and growth oxide layers induce initiation and propagation of the micro-cracks in the thermal barrier coatings(TBCs).MoSi_(2)is selected as the next generation of healing agent because it improves the fluidity of SiO_(2)and accelerates the healing of cracks inside at high temperatures.In this study,the sol-gel method was used to achieve MoSi_(2)@Al_(2)O_(3)core-shell structure which can improve the pre-oxidation resistance of MoSi_(2)in oxygen conditions.Aluminum isopropoxide has been selected as the aluminum source.The effects of temperature,pH value,and water-to-aluminum ratio on weight gain were investigated by orthogonal experiments to obtain the optimal parameters.The influence of post-treatment(including phase compositions and microstructures)was analyzed by XRD,SEM,EDS,and TEM methods.We concluded that the combination of 90℃,pH=4,and the water-to-aluminum ratio of 200 were optimal parameters.The weight gain of the shell layer can achieve the highest level of 22%.The pH value dominates the weight gain because it changes the Zeta potential of the MoSi_(2)surface.After 3 hours of heat treatment in the vacuum furnace,the maximum thickness(around 200 nm)ofα-Al_(2)O_(3)shell layer is obtained at 1200℃.To avoid the pre-oxidation of MoSi_(2),the post-treatment should be operated in a vacuum atmosphere.

关 键 词：溶胶-凝胶 核壳结构 热处理 

分 类 号：TG15[金属学及工艺—热处理]