Effect of Titanium Aluminide Particles on Tribological Properties of Al–40Sn Alloy under Dry Friction Against Steel
摘要
The structure and tribological properties of sintered Al–40Sn alloy reinforced with Al3Ti particles of different volume concentrations were studied. The composite samples were sintered at 710°C for 1 h and then compacted in a closed die at a temperature of 250°C and a pressure of about 300 MPa. Wear resistance tests were carried out using a Tribotechnic tribotester (France) in the absence of lubrication according to the pin-on-disk scheme at a constant sliding speed of 0.6 m/s, increasing the load every 1000 m of the friction path. A steel disk made of hardened grade 40X steel with a hardness of 48–50 HRC was used as a counterbody. It was found that the concentration of hard particles of ~32% by volume ensures maximum wear resistance of the sintered Al–Al3Ti–Sn samples. A further increase in the content of aluminides up to ~40% by volume leads to the formation of a significant number of brittle contacts between the hard particles, which negatively affects the wear resistance of the studied materials. It was concluded that in order to increase the wear resistance of composites of this system, it is necessary to achieve uniform distribution of hard phase particles around the perimeter of matrix grains. It was found that the wear intensity of Al–Al3Ti–Sn composites increases with increasing pressure on the friction surface, while the value of the friction coefficient decreases and is practically independent of the composition of the studied materials. The wear mechanism of the composite samples of hybrid phase composition under dry friction against a steel disk is considered. The wear process of the composites of this system is carried out by two main mechanisms: deformation-oxidative wear through plastic deformation of a thin surface layer and its embrittlement by small oxide particles, as well as fatigue wear through involvement in deformation by shear of grains of the upper layer of the sample with their subsequent delamination along tin interlayers that have exhausted their plasticity resource.