Molybdenum-carbide and tungsten-carbide CVD coatings obtained by Avinit vacuum-plasma technologies

The process of gas-phase deposition of Mo-C and W-C multilayer coatings by pyrolysis of molybdenum and tungsten hexacarbonyls on heat-treated technical steel X155CrVMo12-with high class of surface finish (>10) has been studied. Metallographic research confirms the possibility of low-temperature deposition of high quality coatings with microhardness from ~ 11000 MPa to 20000 MPa at coating deposition rate of 40...170 mkm/h. This provides good adhesion to the substrate materials without reducing the strength characteristics of steel and without deteriorating the purity class of the original surface. The conducted tribological tests reveal high tribological characteristics of the developed coatings and testify to the prospects of their use for increase of wear resistance and reduction of sliding friction coefficient of friction pairs (steel - coating and coating) of precision units in mechanical engineering. Comparison of the properties of the developed coatings with the characteristics of electrolytic hard chromium coatings showed that molybdenum-carbide and tungsten-carbide CVD coatings, obtained by vacuum-plasma technology Avinit, are not inferior to chromium coatings in friction values, can surpass them in hardness up to two times, and in resistance to abrasive wear up to 10 times. According to the aggregate properties, molybdenum coatings can not only compete with electrolytic hard chromium coatings, as hardening and tribological coatings, but also be considered as an alternative to chromium coating in the environmental aspect. On the basis of the conducted research the technological bases of the processes of applying metallic and metal-carbide CVD coatings on the basis of molybdenum and tungsten have been worked out, which are the base for the development of industrial technologies for precision parts of aggregate and engine construction and machine building. Examples of application of the developed coatings in production conditions are given