Towards highly durable bimodal composite claddings using microwave processing

Bimodal composite structures conjugating both high hardness and fracture toughness can effectively counter erosion induced degradation. The present work successfully develops bimodal metal matrix composite claddings using facile and cost-effective microwave technique, exploiting the direct and effective coupling phenomenon of reinforcement with microwave irradiation. For comprehensiveness, unimodal micro-/nano-reinforced clads were also developed. Interestingly, unimodal micro-composite clad showed refined structure compared to nano counterpart which is due to the effective coupling of later with microwave irradiation causing particle dissociation into the matrix. Compared to unimodal claddings, bimodal showed the highest hardness and indentation fracture toughness. In addition to ex-situ reinforcements, intrinsically evolved secondary phases also effectively contributed towards improved mechanical properties. The better performance of the bimodal clad is related to reduced agglomeration and dissociation of the nanoparticles, refined microstructure and constructive interaction between micro and nano-reinforcements. The phenomenal mechanical properties of bimodal composite clad resulted in improved durability compared to unimodal composite claddings under different tribological test conditions.