Prediction of wear coefficient of Al6061-TiO2 composites

In recent years, aluminum alloy based metal matrix composites (MMC) are gaining wide spread acceptance in several interesting applications such as piston, connecting rod, microwave filters, vibrator component, contactors, impellers and space structures. These composites possess excellent wear resistance in addition to other superior mechanical properties such as strength, modulus and hardness when compared with conventional alloys. Of all the aluminum alloys, 6061 is quite popular choice as a matrix material to prepare MMCs owing to its better formability characteristics and option of modification of the strength of composites by adopting optimal heat treatment. From the literature, it is quite evident that the focus has been centered on processing of MMCs and characterization of mechanical properties of MMCs. Tribological characteristics of several MMC systems involving glass, flyash, SiC, Al2O3 as discontinuous dispersoids have been reported. However, meager data are available as regards the theoretical prediction of wear rate of MMCs. Prediction of wear rate gains impetus in present industrial scenario to assess the life of sliding components in advance to avoid huge economic losses that incur due to wear. In the light of the above, the present investigation deals with preparation of Al6061-TiO2 composites by liquid metallurgy route. The extent of incorporation of TiO2 in the composite was varied from 2 to 10 wt%. Microstructure studies, hardness and wear test were conducted on the cast Al6061-TiO2 composites. Pin on disc machine was used to assess the wear resistance of the prepared composites. Load was varied from 10 to 40 N while the sliding distance was from 90 to 540 m. Wear coefficients were evaluated by using Archard's and Yang's theoretical models. Increased contents of TiO2 resulted in higher hardness and lower wear coefficient of the composites under identical test conditions. The wear coefficient of all the Al6061-TiO2 composites studied decreased at higher loads and larger sliding distances. The predicted values of the wear coefficient are in close agreement with the experimental ones.