OBRABOTKA METALLOV

Abstract
The cast iron is rather popular structural material for products and elements, operating in a sliding friction conditions. Nevertheless, functionability of cast iron in friction pairs is significantly limited by loads and speeds, acting on them. The analysis of the causes of failure of cast iron products is given. The reasons of cast irons wear resistance decrease are presented. It is shown that the effective way to improve the wear resistance of cast iron products is a diffusion titanizing. But the process of the application of diffusion titanium coatings have problematic nature, because diffusion layers consist of very fragile titanium carbides, that break off from surface even during process of cooling after process of titanizing. The results of studies of the process of diffusion titanizing of cast iron from the environment of fusible liquid metal solutions is given. The technology of formation of workable coatings, including decarbonizing anneal before the process of tetanizing is developed and patented. This technology provides a high quality functional wear-resistant titanium coating on the surface of the cast iron. Coating formed during 2 hours had the thickness of more than 30 μm. The microhardness of the coating is 25000 MPa, of substrate - 4000 MPa. A transition layer of low hardness (3200 MPa) is detected under the coating. The influence of diffusion titanizing on the wear resistance of cast iron products is investigated. The microstructure and composition of the obtained titanium coatings is investigated. The tribological properties of titanium coatings are investigated, the tribologicalproperties of the friction pairs are investigated. The studies of tribological properties conducted by comparative “pad-roller” is given. The linear wear of coated part with titanium coating is zero, and the uncovered sample wear is 0.02 mm.

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