【作者】 林铁贵；

【导师】 李明伟；

【作者基本信息】 哈尔滨工业大学 ， 材料学， 2011， 硕士

【摘要】 本文以SiC为高辐射填料,分别以硅溶胶和正硅酸乙酯（TEOS）为溶剂采用粉浆法在GH4099薄板表面制备了红外高辐射涂层,研究了涂层的制备工艺,并对涂层的性能进行了表征。首先采用等离子喷涂法在GH4099上制备ZrO₂过渡层,之后采用粉浆法在ZrO₂过渡层上制备高辐射层,优化设计后得出了高辐射涂层的最佳制备工艺:硅溶胶为溶剂的涂层按配比100:8:2:0.25、100:4:2:0.25、100:0:2:0.25:0.8逐层涂刷;干燥制度是先室温干燥,再300℃烧结脱水;烧结工艺是首先用硅溶胶浸渍2 min后烧结1h,烧结之后再用硅溶胶浸渍,之后再300℃烧结0.5h,升温速率均为1℃/min。TEOS为溶剂的涂层按配比16:3:1:0.2、16:1.5:1:0.2、16:0:1:0.2:0.4逐层涂刷;采取干燥制度是先40℃水蒸气干燥,再室温干燥;烧结工艺为涂层首先300℃预烧结,保温30min。自然冷却后利用硅溶胶浸渍2 min后烧结1h,升温速率均是1℃/min。研究表明:硅溶胶为溶剂的涂层干燥过程中出现微裂纹,烧结温度对涂层的表面与截面形貌并无明显影响,而TEOS为溶剂的涂层干燥过程涂层基本不产生裂纹,烧结温度提高后涂层的致密性提高,900℃烧结后的涂层表层中出现了玻璃相;在涂层界面处存在成分突变,高辐射层内ZrO₂存在成分梯度,并且表层的XRD只有YSZ、m-ZrO₂和?-SiC的衍射峰;高辐射层的硬度与弹性模量的值均随着烧结温度的升高而增加,不同温度烧结的涂层在900℃―室温进行100次抗热震性试验后均没有产生宏观裂纹;随着烧结温度与测量温度的升高,涂层的发射率增大,可达0.92,降低涂层厚度发射率降低,TEOS为溶剂的涂层发射率整体上高于硅溶胶为溶剂的涂层发射率;1050℃保温2h后,TEOS为溶剂的涂层表面出现了玻璃相,封填了涂层表面的微裂纹。更多还原

【Abstract】 The high-emissivity coatings was prepared on GH4099 sheet using slurry method. The silica sol and tetraethoxysilane（TEOS）were solvent, respectively. SiC was filler as high-emissivity agent. The preparation process and characterization of the coatings were investigated.First of all transition layer ZrO₂ was prepared on GH4099 by plasma spraying. High-emissivity coatings was prepared on transition layer ZrO₂ by slurry method following. The best process of coating preparation was obtained by optimizing: The coating of silica solvent was brushed layer by layer according to the ratio 100:8:2:0.25, 100:4:2:0.25 and 100:0:2:0.25:0.8.The drying method was that firstly dried at room temperature and then dried at 300℃. The sintering process was that firstly impregnated with silica sol for 2 minutes and sintered for 1h, then impregnated with silica sol again, then sintered at 300℃for 0.5h and the heating rate was 1℃/min.The coating of TEOS solvent was brushed layer by layer according to the ratio 16:3:1:0.2, 16:1.5:1:0.2 and 16:0:1:0.2:0.4. The drying method was that dried in steam at 40℃firstly, dried at room temperature then.The sintering process was that pre-sintered at 300℃for 30 minutes. Then the layer was cooled naturally and then impregnated with silica sol for 2 minutes and finally it was sintered for 1h with 1℃/min as the heating rate.The results showed that micro-cracks appeared on coating of silica solvent during drying, and sintering temperatures had no significant effect on the morphology of surface and cross section. However, there was no cracks appeared on coating of TEOS during drying, and the density was improved with sintering temperature increasing. Glass phase appeared after the coating was sintered at 900℃.Component mutations existed at the coating interface. ZrO₂ composition gradient existed in the high-emissivity coatings. The XRD showed that there was only YSZ, m-ZrO₂ and ?-SiC on the top layer. Both hardness and elastic modulus of the coatings increased with the sintering temperature increasing. And no micro-crack appeared on the coatings with different sintering temperatures after the thermal shock tested for 100 times from 900℃to room temperature.The emissivity of the coating increased to 0.92 with the sintering temperature and measurement temperature increasing. The emissivity reduced with coating thickness decreased. However the emissivity of coatings with TEOS solvent was higher than that of coatings with silica solvent. Glass phase appeared on coating of TEOS solvent after holding 2h at 1050℃, which sealed micro-cracks on the coating surface.更多还原