Preparation and properties of ZrO2/SiO2 composite films modified with PVA and silane coupling agents

Abstract

ZrO₂/SiO₂ composite film was prepared on the surface of zirconium hydride by anodic oxidation+sol-gel sealing composite process to solve the problem of insufficient hydrogen resistance caused by defects such as micropores and microcracks in the anodic oxidation film of zirconium hydride. Using tetraethoxysilane (TEOS) as precursor, polyvinyl alcohol (PVA), silane coupling agent KH570 and A171 were introduced to regulate the sol structure, and the film was densified and stabilized by stepwise heat treatment. The microstructure, composition, phase, thermal behavior and molecular structure of the composite film were systematically analyzed by means of SEM, EDS, XRD, TGDSC and FTIR. The thickness, adhesion, microhardness and hydrogen resistance of the film were tested to reveal the defect repair mechanism and hydrogen resistance mechanism. The results show that PVA and silane coupling agent can significantly refine the sol particle size, improve the film density and interfacial bonding strength. The optimized composite film has a thickness of 27.15μm, a binding force of 70.74 N, a microhardness of 457HV, and an initial dehydrogenation temperature of 710°C, showing excellent mechanical properties and high-temperature hydrogen resistance. The composite film forms a double-layer protective structure through anodic oxide layer support + sol-gel layer sealing, which blocks cracks and pores macroscopically. At the micro level, O-H and C-H chemical bonds are used to capture hydrogen atoms and inhibit diffusion, so as to achieve high-efficiency hydrogen resistance modification of zirconium hydride.Distinct from traditional single-layer hydrogen-resistant coatings, this work constructs a double-layer barrier via anodic oxidation and ternary PVA/KH570/A171 modified sol-gel, and reveals a dual-scale hydrogen resistance mechanism. This process can provide theoretical basis and technical reference for the surface strengthening of zirconium hydride based hydrogen barrier materials in nuclear industry and space energy field.