Titanium oxidation process and how to improve the antioxidant capacity
In sharp titanium oxide at high temperatures, the titanium surface of the titanium silicon compound and a titanium aluminum compound to prevent titanium oxide at temperatures above 700 ℃. Such surface treatment on high temperature oxidation of titanium is very effective, perhaps titanium surface coating of such compounds, titanium porcelain bonding advantageous still further study. From the perspective of anti-oxidation, temperature titanium alloy should not exceed 500 ℃, generally with an oxide film was determined by the difference between the sample and the sample without reduction of the oxide film as indicators of the degree of oxidation, the oxidation of titanium material is to limit temperature one of the main uses. Titanium oxide and oxide synthesis process. Titanium material is stable in air at room temperature, but heating in air or an oxidizing atmosphere, it is prone to oxidation. Depending on the degree of oxidation of the titanium material itself nature and concentration of oxygen in the environment, the heating time and the heating temperature. High temperatures, titanium rapid oxidation, resulting in brittle alloys, mechanical properties deteriorate.
Titanium material increase antioxidant capacity, can coatings and develop ways to be more anti-oxidation of the alloy to achieve. Surface coating processing technology can be used, in a titanium material having a surface coated with a protective layer of a metal (e.g., aluminum, platinum, gold, etc.) or a mixture of metal and oxide layer (e.g., Al + SiO2), in order to improve the anti-oxidation of the titanium material performance. Platinum ion plating, Ti-6Al-2Sn-4Zr-2Mo at 590 ℃ long-term oxidation. The underlying tungsten, platinum, respectively, for coating, its anti-oxidation temperature can be increased to 700 ℃. Adjust titanium components, but also can improve the antioxidant capacity of the titanium material. Select alloying elements Pirin Bedford Worth a ratio greater than 1, cide free energy lower than titanium, in line with Howard fee (Hauffe) laws. Improve the antioxidant capacity of alloying elements: niobium, aluminum, molybdenum, tungsten, tin, silicon and the like. Add these alloying elements to obtain a good antioxidant capacity of titanium alloys, such as Ti-5A1, Ti-5Al-2.5Sn, Ti-4Al-3Mo-1V, Ti-5.8Al-4Sn-3.5Zr-O.5Mo-O. 7Nb-O.35Si-0.06C like. Higher antioxidant capacity intermetallic compound Ti3A1, Ti-Al, Ti-Al-Nb, etc., Ti3A1 oxidation temperature up to 750 ℃, TiAl up to 900 ℃, the antioxidant capacity of Ti-A1-Nb ratio higher TiAl.
A temperature higher than 800 ℃, decomposing the oxide film, the oxygen atoms into the metal lattice through the oxide film, the occurrence of embrittlement. Under normal circumstances titanium oxidation kinetics at low temperatures follows a parabolic law, follow a linear law at high temperatures. Molecular volume of the titanium oxide film is formed, oxide film is greater than the consumption of the metal atomic volume, therefore, the oxide film is formed to cover the entire surface of the metal. At 500 ℃, the oxide film formed on the surface of the titanium material has a protective effect, can prevent permeation of oxygen, titanium materials continue to prevent oxidation. Temperature continues to rise, the loss of protective effect of the oxide film, the occurrence of intense oxidation, diffusion of oxygen into the interior through the metal oxide film to form a clear gas reservoir permeability.