溶胶凝胶法制备无机涂层及热防护性能研究

Study on preparation of inorganic coating by sol-gel method and its thermal protection properties

摘要:

为实现铝合金结构材料在高温环境下的热防护,本文采用溶胶-凝胶法在铝合金表面制备无机锆溶胶涂层。采用正丙醇锆和冰醋酸制备了稳定性良好的锆溶胶,研究了PVP含量对锆溶胶粒子大小和黏度的影响规律,并分析了PVP对溶胶粒子的作用机制。添加60wt%SiO₂填料制备无机涂层,并对涂层进行烧蚀考核,对比研究了不同胶粘剂对涂层结构和热防护性能的影响。根据涂层在烧蚀考核中的宏微观响应,分析了无机涂层在高温下的热防护机制。研究结果表明：冰醋酸含量为22wt%时,锆溶胶稳定性最好；添加7wt% PVP优化后,锆溶胶粒子大小均匀并且具有最好的涂覆性；三种不同胶黏剂基涂层在1300℃火焰烧蚀30s后基体均未发生破坏,水玻璃基涂层烧蚀后发生剥落；较其它胶黏剂涂层,锆溶胶基涂层具有最好的热防护效果。烧蚀过程中,锆溶胶粒子在高温下发生脱水缩合形成纳米氧化锆粒子,弥散分布在填料周围,与填料产生良好的协同隔热作用,使涂层整体具有良好的高温热防护性能。

Abstract:

In order to realize the thermal protection of aluminum alloy structural materials in high temperature environment, the inorganic zirconium sol coating was prepared on the surface of aluminum alloy by sol-gel method. The stability of zirconium sol was prepared by using n-propanol zirconium and glacial acetic acid. The effect of PVP content on the size and viscosity of zirconium sol particles was studied. The mechanism of PVP on sol particles was analyzed. The inorganic coating was prepared by adding 60wt% SiO2, and the coating was ablated. The effects of different adhesives on the coating structure and thermal protection performance were compared. According to the macroscopic response and microscopic morphology of the coating in the ablation test, the thermal protection mechanism of the inorganic coating at high temperature was analyzed. The results show that the stability of zirconium sol is the best when the content of glacial acetic acid is 22wt%. After optimization of 7wt% PVP, the zirconium sol particles are uniform in size and have the best coating property. The silica sol-based coating has the best moldability. After the three kinds of adhesive coatings were ablated for 30s at 1300℃, the substrate was not broken, and the water glass-based coating peeled off after ablation; compared with other adhesive coatings, the zirconium sol-based coating had the best thermal protective ability. During the ablation process, the zirconium sol particles dehydrate and condense at high temperature to form nano-zirconia particles, which are dispersed around the filler and produce good synergistic heat insulation with the filler, so that the coating has good high-temperature thermal protection properties.