梯度多孔Ti的微弧氧化研究

Micro-arc Oxidation of Gradient Porous Ti

摘要:

在硫酸电解液中对致密Ti和梯度多孔Ti样品进行微弧氧化研究。分析了孔隙特性、电流密度和电解液组成对微弧氧化过程中起始电压、击穿电压、起弧时间、氧化膜形貌和厚度的影响，并测量了微弧氧化膜的物相组成。结果表明：与致密Ti样品相比，梯度多孔Ti样品的起始电压和击穿电压提高、起弧时间延长，氧化膜层厚度增加。随着电流密度的增加，梯度多孔Ti微弧氧化反应剧烈，表面膜层的微孔直径增大，孔洞变小，膜层表面粗糙度增加，膜层变厚。当在硫酸电解液中加入少量硝酸镧后，微弧氧化起始电压和击穿电压提高、起弧时间延长，表面氧化膜的平均孔径从200 nm增加到2 μm左右，膜层厚度从27.6 μm增加到35.6 μm，膜层表面粗糙度增加。XRD分析表明，微弧氧化膜主要由Ti、锐钛矿TiO2和金红石TiO2相组成，其中以锐钛矿TiO2为主。

Abstract:

Micro-arc oxidation processes of the dense Ti samples and the gradient porous Ti samples in H2SO4 electrolyte were studied. The effects of pore characteristics, current density, constituents of the electrolyte on initial voltage, breakdown voltage, ignition time, the morphology and thickness of oxidation coatings were analyzed. Phase composition of micro-arc coatings was measured. The results show that the gradient porous Ti samples have higher initial voltage and breakdown voltage, longer ignition time and higher coating thickness compared with the dense Ti samples during micro-arc oxidation. With the increase of current density, micro-arc oxidation reaction becomes acute. In the oxidation coatings, the pore sizes increase and the porosity decreases. Simultaneously, the roughness and thickness of oxidation coatings both improve. When La(NO3)3·6H2O is added in H2SO4 electrolyte, the initial voltage, breakdown voltage and ignition time of the gradient porous Ti samples increase. The mean pore sizes in oxidation coatings and coatings thickness increase form 200 nm to 2 μm and from 27.6 μm to 35.6 μm, respectively. The roughness of oxidation coatings also improves. XRD analysis shows that micro-arc oxidation coatings is composed of Ti, anatase TiO2 and rutile TiO2. The main existing form of TiO2 is anatase TiO2.