非水解溶胶-凝胶法制备硅酸锆薄膜及其性能研究

Zircon has many advantages, such as low oxygen diffusion coefficient, good resistance to thermal shock and excellent chemical and phase stability at high temperature. Furthermore, it also has good thermal expansion matching and compatibility with SiC and Si3N4 substrates. SiC and Si3N4 resistance against the high temperature oxidation and corrosion is greatly improved when zircon film is coated on their surface, so that they have wide application prospect in the fields of aerospace, national defense and civilian industries, etc. This project takes the lead in preparing zircon film on SiC or Si3N4 substrate at low temperature by non-hydrolytic sol-gel (NHSG) method in the world. The stability mechanism of non-hydrolytic zircon sol and the effect of process parameters on the film quality are investigated so as to reveal the relationship between oxidation resistance, film microstructure and preparation processing. A new method is developed for fabricating zircon film at low temperature, which expands the application field of NHSG method. The stable zircon sol is achieved through optimizing new organic solvent and sol stabilizer. The cracking problem of gel film during the drying process is solved by the original drying technology with high temperature and high solvent vapor pressure. The additive is introduced in the NHSG system to promote the low-temperatuer densification of film. Base on this, the innovation technology with independent intellectual property is created for preparing zircon film. Therefore, this project is not only of important theoretical significance, but also of great practical application.

硅酸锆不但具有氧扩散系数小、抗热震性强、高温化学与相稳定性好等优异性能，而且还与SiC和Si3N4基体有很好的热膨胀匹配性与相容性，表面涂覆硅酸锆薄膜的SiC和Si3N4材料，其高温抗氧化、耐腐蚀性能大幅提高，在航空航天、国防以及民用工业等领域应用前景广阔。本项目在国际上率先采用非水解溶胶-凝胶法（NHSG）低温制备硅酸锆薄膜。通过解析非水解硅酸锆溶胶的稳定机制和工艺参数对硅酸锆薄膜质量的影响规律，揭示硅酸锆薄膜抗氧化性能与薄膜结构、制备工艺之间的内在关系，开创一种低温制备硅酸锆薄膜的新方法，拓展NHSG法的应用领域。通过优选新型有机溶剂与溶胶稳定剂形成稳定硅酸锆溶胶，独创高温高溶剂蒸气压的干燥新工艺解决凝胶膜干燥开裂难题，首次在非水体系中引入致密化助剂促进薄膜的低温致密化，形成具有我国自主知识产权的硅酸锆薄膜制备新技术。因此，本项目不仅具有重要的理论研究意义而且还具有很大的实际应用价值。

硅酸锆具有熔点高、热导率低、膨胀系数小、高温化学与相稳定性好等优异性能，此外还具有氧扩散系数小、抗热震性强等特点，再加上硅酸锆与SiC 和Si3N4 基体有很好的热膨胀匹配性与相容性，因此表面涂覆硅酸锆薄膜的SiC和Si3N4 材料，其高温抗氧化、耐腐蚀性能大幅提高，在航空航天以及民用工业等领域应用前景广阔。.本项目首先采用一种新型溶胶-凝胶法制备硅酸锆薄膜。在此基础上采用非水解溶胶-凝胶（NHSG）法低温制备硅酸锆薄膜，解析了水解以及非水解硅酸锆溶胶的稳定机制，探讨了工艺参数对制备硅酸锆薄膜质量的影响规律，研究了硅酸锆薄膜抗碱液腐蚀以及抗氧化性能。与传统溶胶-凝胶法需要在1250℃以上的高温制得硅酸锆薄膜不同，采用新型溶胶-凝胶法以及NHSG法能够在850~1000℃制得高质量的硅酸锆薄膜；在新型溶胶-凝胶体系中添加硅烷偶联剂（APTES）有利于提高硅酸锆薄膜的致密度，进而提高其抗氧化性能；将四丁基溴化铵（TBAB）引入到NHSG体系，并且采用TBAB浓度梯度的镀膜形式，既提高了硅酸锆薄膜与基体的结合力，又增加了薄膜的致密性；新型溶胶-凝胶法以及NHSG法制备的硅酸锆薄膜具有很好的抗碱液与抗氧化性能。此外，本项目还拓展了研究范围，采用NHSG法制备了硅酸锆包裹炭黑色料、硅酸锆和氧化锆晶须等低维陶瓷材料，搭建了NHSG法制备多种低维陶瓷氧化物材料的科研创新平台，为后续进一步的深入研究打下了坚实的基础。.通过本项目的研究，在国内外核心期刊上发表学术论文28 篇（其中10篇被SCI/EI收录）；申报了4 项国家发明专利（其中3项已经授权），培养硕士研究生18人。