TC4在锆盐体系下微弧氧化膜层的生长特性研究

目的通过建立ZrO_2/TiO_2复合陶瓷膜层的氧化时间与膜层生长的动力学关系,探究膜层生长对膜层显微硬度的影响规律,寻找制备高硬度微弧氧化膜层的最佳时间。方法在锆盐溶液体系和已优化的电参数条件下,对TC4进行不同时间的微弧氧化处理,分析所得膜层的表面和截面形貌、元素分布及相组成,进行膜层表面孔隙率和显微硬度的测定并分析。结果测试氧化时间内膜层生长表现出不同的动力学特征和宏观表象,膜层的生长分为两个阶段:第一阶段膜厚呈线性增加,第二阶段膜厚增长速率减缓。表面孔隙率随时间的增大而增大。在氧化15 min时所得的膜层硬度最高,且随时间的增加,膜层的显微硬度呈先增后减的趋势。结论影响微弧氧化膜层显微硬度的主要因素包括膜层相组成和表面结构。在微弧氧化膜层厚度呈线性增长的过程中,显微硬度线性增大;在膜厚缓慢增长的过程中,显微硬度降低。

Growth Characteristic of Micro-arc Oxide Coating on TC4 in Zirconium Salt System

The work aims to explore influence law of coating growth on its micro-hardness and determine the best time of preparing high-hardness micro-arc oxide coating by establishing dynamic relationship between oxidation time and coating growth of ZrO2/TiO2 composite ceramic coating. Micro-arc oxidation was performed to TC4 for different time provided with zirconium salt system and optimized electrical parameters to analyze coating surface and cross-section morphology, elements distribution and phase composition, measure and analyze microhardness and porosity of the coating. The coating growth exhibited different dynamic characteristics and macroscopic appearance in the test oxidation time. There were two stages during the coating growth: the coating thickness increased linearly in the first stage, and then growth rate slowed down in the second stage. The surface porosity increased over time. The hardness was the highest when the oxidization has last for 15 min. And the micro-hardness first increased and then decreased over time. The main factors influencing microhardness of MAO coating are phase composition and surface structure. The micro-hardness increases linearly as coating thickness exhibits linear growth; and the micro-hardness decreases as coating thickness exhibits slow growth.