Palekhova I. Formation of doped titanium coatings on structural materials under conditions of self-propagating high temperature synthesis

The thesis is devoted to the development of new titanium coatings doped with aluminum, silicon and chromium on carbon steels (steel 20, steel 45, steel U8) under the conditions of thermal self-ignition of SHS–charge. The effect of alloying elements was studied and optimal compositions of SHS –charge were developed using the method of mathematical planning of an experiment. Taking in to account the effect of temperature and time of isothermal exposure on the physico-mechanical and operational properties of steels, the optimum treatment conditions were determined. It has been established that the highest performance characteristics of structural materials with multicomponent titanium coatings are provided by the SHS- charge of the following composition: 20-25% of the chromium component, 22-25% of titanium, 5-7% of chromium, 8-11% of silicon, 10-15% of aluminum, 6% activator (I2, NH4Cl) and ballast material (Al2O3) – the rest. The regularities of the influence of the chromium component and alloying elements in the SHS charge on the maximum process temperature and the temperature of the onset of self-ignition, as well as the region of the absence of a heatwave, are investigated. It has been established that compared with diffusion treatment under isothermal conditions, the heat resistance of SHS coatings increases 1,9-2,5 times, corrosion resistance 1,5-1,9 times, wear resistance 1,8-2,0 times, the adhesives treng this 1,25–1,31 times, the level of residual compressive stresses increases by 17–28%, and micro britt leness decreases by 1,18–1,24 times. New titanium coatings alloyed with chromium and aluminum and the technology for their production have passed pilot testing in the UC Vodokanal (Zaporozhye) and PJSC Zaporozhoks (Zaporozhye). Keywords: synthesis, thermal autoignition, coating, material, alloying, wearresistance, microhardness, microfragility.