Preparation of Ti3Si0.8Al0.2C2 Bonded Diamond Composites and Their Friction Properties Coupled with Different Counterfaces

Abstract

Polycrystalline diamonds were sintered with the binder of Ti3Si0.8Al0.2C2 to solve the shortcomings of conventional metal binders and ceramic binders. Ti3Si0.8Al0.2C2 bonded polycrystalline diamond composites have been synthesized from a mixture of Ti3Si0.8Al0.2C2 powder (40 wt%) and diamond powder under 4.5–5.5 GPa at 1050–1300°C by high press and high-temperature technology. The characteristic peaks of TiC were observed at 4.5 GPa and above 1100°C. From the microstructure analysis, the diamond particles are equally dispersed throughout the Ti3Si0.8Al0.2C2 matrix and firmly bound to the matrix. The effects of the sintering conditions, test parameters, and counterparts on the friction properties of diamond composites were systematically analyzed. The friction coefficient between diamond composite and glass counterpart is between 0.18 and 0.33 and increases significantly at the speed of 400 rpm/min. SEM and EDS analysis show Ti3Si0.8Al0.2C2 has a strong holding force on the diamond particles. The wear mechanism is mainly abrasive, and there are obvious grooves on the surface of the glass ball. The friction coefficient of diamond composite sintered at 1050°C with POM decreases monotonically with increasing load and reaches the minimum value of 0.42 at 12 N. The higher sintering temperature (1150°C) resulted in lower friction coefficient for diamond/POM pairs. The friction coefficient of diamond/PP pairs decreases first and then increases with increasing load, reaching a minimum value of 0.431 at 10 N. The wear mechanism of PP and POM is a combination of abrasive wear and adhesive wear, while the abrasive chips of POM are small salt-like particles and the abrasive chips of PP are long flocs. The wear track of PP balls has a smoother surface than that of POM balls. For an Al pair, the friction coefficient of diamond composite sintered at 1150°C is higher than that of the composite sintered at 1050°C except for the 10 N load. The friction coefficient of the diamond composites with Cu pairs varies slightly with increasing load, with values ranging from 0.443 to 0.518 and decreases with increasing speed, reaching a minimum value of 0.396 at 600 rpm/min. The wear mechanism of Cu and Al is mainly based on adhesive wear. The presence of the diamond second phase improves the stability of Ti3Si0.8Al0.2C2 compared to the high-pressure treatment of single phase Ti3SiC2. The analysis of friction properties indicates that Ti3Si0.8Al0.2C2 bonded diamond composites are promising candidates for superhard tool materials.