No abstract

AA7075 is used in several automobile applications due to its low density and better mechanical properties. However, the friction and wear properties of AA7075 are not up to the mark to extend its application for tribological applications. Hence, this present study focuses on improving the mechanical and wear properties of AA7075 through different reinforcements like h-BN and MoS 2 nanoparticles. Two different composites namely AA7075/h-BN and hybrid AA7075/h-BN/MoS 2 are produced using a stir-squeeze casting process by varying weight percentages of h-BN and MoS 2 particles and their mechanical and tribological characteristics are compared. Physical characterization like morphology, phase structure, density, and porosity values are determined. The reinforcement of MoS 2 and h-BN particles has modified the microstructure in terms of dendrite formation. Hardness is measured and correlated with the tensile strength of the developed composites. Maximum ultimate tensile strength (UTS) of 361.5 MPa is obtained for AA7075/h-BN composite as compared to hybrid AA7075/h-BN/MoS 2 and AA7075. A higher hardness of 164.39 HV is attained for AA7075/1.0h-BN/0.5MoS 2 composite as compared to AA7075/h-BN composites and AA7075. Tribological characterization is studied using the pin-on-disc apparatus at an applied load of 40 N, a sliding distance of 1000 m, and a sliding velocity of 2 m s −1 . Higher delamination and adhesion wear exhibited by AA7075 is controlled with the reinforcements of h-BN and MoS 2 nanoparticles. Comparatively, the hybrid AA7075/h-BN/MoS 2 has shown better tribology behavior than the other composites. Additionally, the various wear mechanisms of AA7075/h-BN and hybrid AA7075/h-BN/MoS 2 composites during the sliding are studied.

In addition to the properties of reinforcement, the tribological parameters (temperature, applied load, and sliding distance) play a vital role in determining the tribological characteristics of the composites. Though there are studies related to the AA7075/h-BN composites, the influence of tribological parameters on the friction and wear characteristics is not addressed. In this regard, a solemn attempt has been made in this research work to study the role of tribological parameters on the tribological characteristics of AA7075/h-BN composites. Taguchi method and genetic algorithm are employed to predict the impact of tribological parameters on the wear resistance of AA7075 and AA7075/h-BN composites. The formulation of genetic algorithm models along with regression analysis is used for estimating the effect of each input parameter on the tribological behaviour of the AA7075 MMCs. The microstructure of AA7075/h-BN composite is analysed and found that the formation of rosette-like dendrites with increased mechanical and tribological properties. The optimum wear rate and Coefficient of Friction (CoF) values of AA 7075/h-BN composite is obtained with input process parameters at a temperature of 30 °C, applied load 10 N, and sliding distance of 1000 m respectively. The further results show that the temperature and load play a vital role in the specific wear rate and coefficient of friction of AA7075 MMCs, leading to improved tribological performance characteristics.

No abstract

No abstract