Carburizing surface treatment of titanium wire
Titanium wire and carbon form a kind of stable carbide with higher hardness. The growth of the carbonized layer between titanium and carbon is determined by the diffusion rate of titanium in the carbonized layer.
The solubility of carbon in titanium is small, which is 0.3% at 850x: and about 0.1% B at 600C. Because the solubility of carbon in titanium is small, the surface hardening is basically achieved only through the titanium carbide layer and the deposition layer of its lower edge. Carburizing must be carried out under the condition of deoxidization, because the hardness of the surface layer formed by the powder applied to the surface of carbon monoxide or carbon monoxide containing oxygen can reach 2700mpa and 8500mpa, and it is easy to peel off.
In contrast, in deoxidation or decarburization conditions, a thin titanium carbide layer may be formed when carburizing in charcoal. The hardness of this layer is 32ouompa, which is consistent with that of titanium carbide. The depth of carburizing layer is larger than that of nitriding layer under the same condition. Under the condition of oxygen enrichment, the effect of oxygen absorption on the hardening depth must be considered. Only under the condition of very thin layer thickness, carbon powder can form enough adhesion strength in air or argon methane atmosphere. Compared with this, gas carburizing agent can form a very hard and good adhesion hardening layer of titanium carbide. At the same time, when the temperature is between 950t: and 10201: the hardening spread is between 50fim and. With the increase of the thickness of the layer, the tic layer becomes brittle and tends to peel off. In order to avoid the carbon inclusions invading the tic layer due to the decomposition of rane, the gas carburizing should be carried out in inert gas with a prescribed dosage of 2% rane. When propane additive is used and methane is used for carburizing, a lower surface hardness is formed. When the adhesion force reaches 0 kPa and propane is carburized by gas, although the thickness of hardened layer measured is very thin, it has the best wear resistance. Hydrogen is absorbed by gas carburizing agent, but it has to be removed again during vacuum annealing.