Arendar L. The role of phosphide eutectics in formation of structure and some physico-mechanical properties of surface layers of pearlitic cast iron under friction

In the theses, basing on the complex experimental testing of wear-resistance of pearlitic grey and high-strength cast irons alloyed with phosphorous, the investigation of the phase composition and structure evolution during friction, experimental and theoretical analysis of friction heat release, the important scientific and technical problem of assuring wear-resistance of the above cast irons in service important range of velocities and pressures has been substantiated and solved. The data about the significant effect of phosphide eutectic, its distribution and morphology on the physicomechanical properties of phosphorous cast irons has been proved. It has been established that due to friction the phosphide eutectic is localized in thin (to 5 µm) subsurface layers of the metal and on the friction surfaces of the metal and on the friction surfaces, its quantity by the factor of coating surface increases and the reorientation towards the slip vector direction occurs. The mechanism of phosphide eutectic influence on the wear-resistance of the grey and high-strength phosphorous cast irons was substantiated. Temperature flashes of phosphide eutectic inclusions cause their plastification area, increase on the friction surface and, as result, decrease in contact pressures, and also reduction of mean integral temperature and improvement of wear-resistance. A new chemical composition of grey and high-strength phosphorous cast irons, has been proposed аnd has been improved as the elements of non-standard investigation.