Tribological characteristics of LM13 alloy based ilmenite-boron carbide reinforced hybrid composites for brake drum applications

Abstract

Aluminium matrix hybrid composites reinforced with a combination of naturally occurring ilmenite mineral particles (FeTiO3) and synthetically processed boron carbide ceramic particles (B4C) were processed using stir casting route. Reinforcement loading was varied between 0 and 15 wt. percentage (wt.%). For each loading, the two type of fillers were mixed in three wt.% ratio of 1:3, 1:1, and 3:1. Particle size range for both fillers was 106–125 μm. Operating temperature, applied load, and sliding distance were in the range of 25–300 °C, 9.8−49.0 N, and 0−3000 m respectively. Optical and scanning electron micrographs showed nearly uniform distribution of reinforced particles in the matrix. Grain size reduction and morphological changes in the constituent phases of matrix material were noted. Pin-on-disc wear set-up was used to evaluate the wear behaviour of composites (ASTM G99 standard). With increase in operating temperature, the wear rate increased. A sharp rise in wear rate was observed beyond 200 °C. 15HA-31 composite (loading: 15 wt.%; B4C to Ilmenite weight ratio: 3:1) showed maximum improvement in wear rate at all the operating temperatures exhibiting 52−71% reduction in maximum wear rate over the reference sample. Ilmenite particles reduced the coefficient of friction, promoted strong interfacial bonding, and caused early oxidation of sliding surface. On the other hand, B4C particles increased the stability of tribolayer, caused grain refinement, and resulted in morphological changes from acicular to globular for the constituent phases of matrix. Wear rate behaviour of 15HA-31 composite was comparable to the commercially used brake drum material.