Study Of Preparation And Performance Of High-frequency Induction Oxidation Layer On Titanium Alloy

Titanium alloy as a new structural and functional material has a series of excellent properties, such as high melting point, better plasticity, low density, high specific strength, strong corrosion resistance in sea and so on. In recent years, Titanium alloy is mainly used in some fields such as: aerospace and military industry, and also is progressively used in so many new fields of ordinary industry and civil affairs. But titanium alloy appears a low hardness, easily conglutinating in heating, reduction of plasticity and strength easily resulted from high temperature oxidation and hydrogen brittle, crack corrosion under situations, such as high temperature or pH<2. In addition, titanium alloy shows poor wearing resistance because the oxide on it has a low protection ability. These shortcomings have restricted the application of titanium alloy, and surface treating technology is effective way to improve the properties of titanium alloy.High-frequency induction oxidation is a new technology to form oxidation layer on metal surface. The high-frequency induction oxidation is a new technique on the surface of titanium alloy in comparing to other surface treatment techniques due to its low energy cost, high efficiency, and good work environment. In the thesis, the preparation of oxidation layer on the surface of Ti6Al4V alloy by high-frequency induction oxidation from 800℃to 950℃has been studied. The factors on performances of oxidation layer were analyzed and some laws were shown as follows: (1) relation between different treating temperature and the oxidation layer's performances; (2)relation between the treating time and the oxidation layer's performances; (3)relation between the different oxide medium and the ceramic coating's performances. Then, microstructure and phase composition were researched by SEM and XRD. At last, models of oxidation kinetics are proposed based on our results.This work indicates that from 800℃to 950℃, thickness and hardness of oxide layer increased by the increasing of treating time and treating temperature. The study also shows that thickness, compactibility, uniformity and cohesion of the layers oxidized in oxygen medium are much better than those in dry air. Furthermore, it is shown that the oxidation layers are mainly composed of TiO2 and Al2O3 from XRD. The thickness of layer is 11～34μm, and the hardness is 500～1589HV.In comparing to micro-plasma oxidation and thermal oxidation, the...