自修复金属搪瓷高温防护涂层

搪瓷涂层作为一种惰性涂层,能与大多数金属零部件相容并提供优异的腐蚀防护效果。但搪瓷的高温软化及本征脆性限制了其在高温以及热冲击等苛刻环境下的服役。总结了国内外解决搪瓷涂层烧结温度与服役温度相矛盾、涂层热循环时易剥落等问题的最新进展:首先介绍了通过复合陶瓷颗粒以及对搪瓷/陶瓷界面反应的调控,实现提高涂层使用温度的同时不改变其熔炼和烧结温度的方法体系;接着分析了影响搪瓷涂层抗热震剥落性能的因素(包括搪瓷釉热膨胀系数、涂层/基体界面结合、搪瓷釉力学性能等)。基于搪瓷的硅氧网络基本结构,从热物理性能以及力学性能角度改性等方案仅能在有限范围内提高其抗热震剥落能力的现实,最后提出了发展自修复金属搪瓷高温防护涂层,从根本上解决搪瓷开裂与剥落的问题。

Self-healing High-temperature Protective Metal-Enamel Composite Coatings

As an inert overlay coating, enamel coating can be compatible with most metal parts and provide excellent corrosion protection effect. However, the property of high temperature softening and inherent brittleness of enamel coating limit its application at high temperature and in thermal shock environments. The current research progress in solving contradiction between enamel sintering temperature and service temperature as well as the poor thermal shock resistance during thermal cycling was reviewed. Firstly, the method system of improving the coating application temperature without changing its melting and sintering temperature through composite ceramic particles and controlling the enamel/ceramic interface reaction was introduced. Then, the factors affecting the thermal shock resistance of enamel coating were analyzed, including the thermal expansion coefficient of enamel, binding of enamel/alloy interface, mechanical properties of enamel, etc. Due to the Si-O network structure, it is hard to enhance thermal shock resistance of enamel coating largely by thermophysical and mechanical properties modification. Based on this face, self-healing metal-enamel composite coating is proposed, which can fundamentally solve the problem of enamel cracking and spallation.