Preparation and performance of mullite/yttrium silicate composite coatings

doi:10.3969/j.issn.1001-1935.2026.04.007

Abstract

Abstract: To enhance the high-temperature stability of silicon carbide ceramics,a spraying-sintering process was employed.Three slurries were prepared with mullite powder,yttrium silicate powder,and mullite/yttrium silicate mixed powder with a mass ratio of 4∶1,respectively.The slurries were then sprayed onto 10 cm × 10 cm × 5 cm silicon carbide substrates to form coatings of 100 μm in thickness and heat-treated at 1 400,1 500,and 1 600 ℃ for 3 h to obtain coated samples.The effects of the heat treatment temperatures on the microstructure and performance of the mullite coating,yttrium silicate coating,and mullite/yttrium silicate composite coating were investigated.The results indicate that:(1)the single-component mullite or yttrium silicate coating exhibits defects such as coarse grains,high porosity,and susceptibility to cracking;(2)in the mullite/yttrium silicate composite coating,mullite transforms from granular morphology into columnar crystals,forming a stable network structure that significantly enhances the coating density and strength;as the heat treatment temperature increases,a eutectic phase gradually forms between mullite and yttrium silicate,promoting the growth of mullite grains;the grain size increases significantly with the rising temperature,while intergranular porosity first decreases and then increases;(3)the mullite/yttrium silicate composite coating heat-treated at 1 500 ℃ demonstrates the optimal overall performance,which exhibits excellent thermal stability and adhesion in a high-temperature vacuum environment,effectively inhibits the reactions between silicon carbide and heat-resistant steel and shows outstanding thermal shock resistance.

Key words: magnesium metallurgy, mullite, yttrium silicate, composite coatings

摘要： 为提高碳化硅陶瓷的高温稳定性,采用喷涂-烧结工艺,分别以莫来石粉体、硅酸钇粉体、质量比为4∶1的莫来石/硅酸钇的混合粉为主要涂层原料,制成浆料后在10 cm×10 cm×5 cm的碳化硅基体表面喷涂100 μm厚,经1 400、1 500、1 600 ℃热处理3 h制备了涂层试样,研究热处理温度对莫来石涂层、硅酸钇涂层、莫来石/硅酸钇复合涂层的显微结构与性能的影响。结果表明:1)单一莫来石涂层或硅酸钇涂层存在晶粒粗大、孔隙率高,易开裂等缺陷。2)莫来石/硅酸钇复合涂层中,莫来石由原来的颗粒状转变为柱状,并形成稳定的网络结构,显著提高了涂层的致密度和强度;随着热处理温度的升高,莫来石与硅酸钇之间逐渐形成共晶相,促进莫来石晶粒生长,其晶粒尺寸随温度升高显著增大,晶间孔隙呈现先降后升的趋势。3)1 500 ℃热处理所得的莫来石/硅酸钇复合涂层表现出最佳的综合性能,在高温真空环境下热稳定性与附着性良好,能够有效抑制碳化硅与耐热钢的反应,抗热震性优异。

关键词: 镁冶炼, 莫来石, 硅酸钇, 复合涂层

CLC Number:

TQ175

Min Zhiyu, Yuan Hongyue, Chen Mao, Chen Yongqiang, Fan Bingbing. Preparation and performance of mullite/yttrium silicate composite coatings[J]. Refractories, 2026, 60(4): 311-319.

闵志宇, 袁洪跃, 陈毛, 陈勇强, 范冰冰. 莫来石/硅酸钇复合涂层制备与性能研究[J]. 耐火材料, 2026, 60(4): 311-319.

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URL: http://www.nhcl.cn/EN/10.3969/j.issn.1001-1935.2026.04.007

http://www.nhcl.cn/EN/Y2026/V60/I4/311

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