The effect of sintering with high frequency induction on the mechanical and tribological properties of hybrid aluminum matrix composites

In this study, the microstructure, mechanical and tribological properties of Al-Mg-Si-Cu-B4C/SiC-Gr-TiO2-SiO2 hybrid metal matrix composite materials were investigated. For this purpose, Al-Mg-Si-Cu-B4C-Gr and Al-Mg-Si-Cu-SiC-Gr powder blends were reinforced with different weight percentage of TiO2 (0-1-3-5-7) and SiO2 (0-1-3-5-7) particles. Thereafter the mixtures with an average particle size of 0-61 micron were mixed for 30 minutes at 30 rpm in a planetary ball mixer. The mixed hybrid powders were uniaxially pressed in a mold at 220 MPa. The hybrid compacts were sintered under low vacuum (250-350 Torr) with the induction energy produced by the high frequency (900 kHz) induction generator at 600˚C for 300 seconds. The phases and microstructure of sintered hybrid specimens were investigated with XRD (X-ray Diffraction), SEM (Scanning Electron Microscope) and optical microscope. The mechanical and tribological properties of the specimens were investigated with wear test and macro hardness measurements. The microstructure images show that the reinforcements have a homogeneous distribution in the aluminum matrix. The wear tests were carried out with 2 N load and 500 m distance with a sliding speed of 10 cm per second. The results show that samples with SiC reinforcement have a higher friction coefficient than the samples with B4C reinforcement. Also the sample with SiC and wt. 7% TiO2 reinforcement has the lowest volume loss after wear test. There are no significant improvement in the hardness values for different amount of reinforcement. Also it was found that SiO2 reinforcement has a negative effect on the hardness values. The induction produced hybrid composite materials can perform better mechanical and tribological results if the wettability of the reinforcing ceramic particles can be improved by working with higher sintering temperatures and lower weight percentage of reinforcements.