多孔SiC表面WC+W_(2)C涂层的制备及其结构研究  

Preparation and Structure of WC+W_(2)C Coating on Porous SiC Surface

作　　者：刘琪 桑可正[1] 曾德军[1] LIU Qi;SANG Ke-zheng;ZENG De-jun(School of Materials Science and Engineering,Chang'an University,Xi'an 710064,China)

机构地区：[1]长安大学材料科学与工程学院,西安710064

出　　处：《表面技术》2022年第3期226-233,共8页Surface Technology

基　　金：陕西省自然科学基金研究计划项目(2018JQ5120)。

摘　　要：目的 改善金属与SiC的润湿性,避免金属熔渗过程中损伤多孔SiC基体。方法 采用氧化烧结法制备了多孔SiC基体,再采用溶胶氢还原法于900℃在多孔SiC表面制备了WC+W_(2)C涂层。通过X射线衍射仪和扫描电子显微镜研究了涂层的结构和组成,以及热处理温度、时间和溶胶吸收次数对涂层的影响。结果 热处理温度为900-1100℃时,W与C发生反应并形成了WC与W_(2)C,但温度增加至1350℃时,涂层与基体发生反应,形成了WSi_(2)化合物。在900℃时,随着热处理时间从1h增加至3h,涂层颗粒聚集长大,颗粒之间的距离增加。随着吸胶次数的增加,经还原后的涂层颗粒数量增多,平均粒径不断增加,吸胶5次后,涂层颗粒所占表面区域面积百分比达到饱和,约为40%。吸胶6次后,涂层颗粒的平均粒径达到0.53μm。结论 WC+W_(2)C涂层以颗粒状分布在基体表面形成涂层。通过增加吸胶次数到6次,可以有效地增加涂层颗粒的数量以及所占面积百分比。基于涂层与金属润湿效果的最佳工艺条件是在试样吸胶6次后进行还原热处理,还原温度为900℃,时间为1 h。To improve the wettability of the metal with Si C and to avoid damage to the porous Si C substrate during the infiltration process.A certain amount of Si C powder was mixed with about 5wt.%alcohol-soluble phenolic resin.Then,the φ15 mm×4mm specimens were obtained by cold pressing with 84 MPa press for 1 min.Finally,porous Si C substrates were prepared by oxidation sintering.The raw materials were prepared according to the mass ratio of ammonium metatungstate,citric acid,ethylene glycol and water-soluble phenolic resin 6:3:2:0.84.By adjusting the heating time to control the evaporation of solvent deionized water,the molar ratio of W to C is 1:2 and the solid content of ammonium metatungstate is 50%.One side of sintered porous Si C ceramic sample is immersed in the sol,and the pore of Si C ceramic was automatically impregnated with the sol by capillary force.When the surface of Si C ceramic sol exudated,took out the sample and filter paper to scrape off the surface of excess sol,and then dried.Finally,the sample was placed in a tubular furnace to begin hydrogen reduction.Samples with WO_(3) layer were obtained by heating them to 500℃at a heating rate of 10℃/min for 3 h.Then it was heated to 800,900,1000,1100 and 1350℃at a heating rate of 10℃/min for 3 h (among which,1 h,2 h and 3 h were set at 900℃),and WC+W_(2)C coating was obtained.In addition,WC+W_(2)C coatings could be obtained on the porous Si C surface by the sol-gel hydrogen reduction method at 900℃.The structure and composition of the coating,the effects of heat treatment temperature and time as well as the times of suction of the sol on it,were studied by X-ray diffractometry and scanning electron microscopy.The results showed that W and C could react and form WC and W_(2)C when the heat treatment temperature was between 900℃and 1100℃,but the coating reacted with the substrate and the WSi_(2) compound appeared when the temperature was increased to1350℃.With the increase of heat treatment time at 900℃,the coating particles gradually ga

关 键 词：润湿性 溶胶凝胶 碳化硅 涂层 WC+W_(2)C 

分 类 号：TG174.44[金属学及工艺—金属表面处理]