Surface Wear Behavior and Friction and Wear Mechanism Studies of A356/3 wt.% Al3Zr Composites

A direct-melt reaction was used to successfully synthesize A356/3 wt.% Al3Zr composites at 750 degrees C, 770 degrees C and 790 degrees C from the Al-K2ZrF6 system. The friction and wear characteristics of composites synthesized at 750celcius were determined by carrying out dry sliding tests of varying loads and sliding speeds. Polarized light microscopy, metallurgical microscopy, x-ray diffraction, scanning electron microscopy and confocal laser scanning microscopy were applied to identify the phase compositions and observe the microstructure and morphology of the worn surfaces. Finally, the wear mechanism of composites and matrix was analyzed by observing the SEM pictures of the wear surfaces. The results indicate that Al3Zr particles are successfully formed in the matrix. At 750celcius, the particles were the smallest and dispersed well in the matrix. The size of the reinforced particles increases with increasing reaction temperature. The hardness of the composites is greatly improved compared to that of the matrix, and the highest hardness reaches 245.6 HV. The experiments show that the friction coefficient of the composites is lower than that of the matrix, and the smallest average friction coefficient is 0.367. The volume wear loss of the composites is less than that of the matrix. The wear mechanism of composites is mainly adhesive wear and is accompanied by abrasive wear and fatigue wear because of the change in experimental parameters. Eventually, delamination wear occurs, and the wear resistance is better than that of the matrix.

Automated summary

A356/3 wt.% Al3Zr composites were successfully synthesized via direct-melt reaction, showing improved hardness and wear resistance compared to the matrix. The composites exhibit lower friction coefficient, and the predominant wear mechanism is adhesive wear.