Wear-resistant boride composites with high percentage of reinforcement phase
A highly wear resistant sintered, hot pressed, or otherwise compacted ceramic composite material is described, consisting of two discrete phases of the form AlxMgyB14 where x and y ≦1 or like hard, orthorhombic compounds, and TiB2 or like Group IVB transition metal di-borides, and with an unexpectedly high contentof transition metal di-boride in the range from 40 to 90 percent (28 to 85 volume percent).
Wear performance of in-situ Al–TiB2 composite
The wear resistance, interpreted as the extent of reduction in wear rate, of in-situ Al–TiB2 composite produced by stir casting route was evaluated by dry sliding wear. Wear evaluation was carried out on composites with varying volume fraction of TiB2, peak aged Al–Cu–15 Vf% TiB2 and carbon steel. It was found that increased volume fraction of the TiB2 reinforcement had not led to an appreciable increase in the wear resistance of the composite. The wear resistance of Al–10 Vf% TiB2 composite was found to exhibit a wear resistance 18.5 times higher than the unreinforced Al, whilst the Al–Cu–15 Vf% TiB2 composite was 3.1 times higher in resistance than unreinforced Al–Cu matrix. Replacement of the Al matrix with Al–Cu in the 15 Vf% composite did not improve the wear performance. The Al–15 Vf% TiB2 composite was shown to have almost the same wear resistance as plain carbon steel. Microstructural examination revealed that Al3Ti flakes gave way immediately to the crushing load during the wear process. However, the TiB2 particles resisted the wear process until rounded edges were configured.
The effect of participate reinforcement on the sliding wear behavior of aluminum matrix composites
The aim of the present investigation is to characterize the friction and wear behavior of aluminum matrix composites reinforced with particulates of SiC, TiC, TiB2, and B4C. Sliding wear tests were conducted at two loads (80 and 160 N) using a pin-on-disc apparatus and under dry conditions. The results of the investigation indicate that the coefficient of friction of the composites is about 30 pct lower than that of pure aluminum, while the wear rates of the com- posites are lower by a factor of about 3 and 100 at loads of 80 and 160 N, respectively. The type and size of the reinforcement have a negligible influence on the wear rate and the coefficient of friction of the composites. However, the volume fraction of the reinforcement has a marginal influence on the wear rate. Though the coefficients of friction and the wear rates of the com- posites were broadly similar, the Al-TiC composite alone exhibits a somewhat higher wear rate. The above results of the present investigation have been rationalized on the basis of the inverse rule of mixtures and the existing models for friction and wear.