Study on Effect of Milling Time on the Mechanical and Wear Properties of the ZA40-B4C-Graphene Hybrid Nanocomposites Fabricated by Vacuum Hot-Pressing

In this study, the effect of mechanical milling time on the mechanical properties, wear behavior and microstructure of B4C and graphene-reinforced ZA40 metal matrix hybrid nanocomposites (HNCs) fabricated by vacuum hot-pressing method was investigated. ZA40-based metal matrix hybrid nanocomposite powders were mixed using the mechanical milling method to obtain a homogeneous distribution of the reinforcement particles in the matrix. Milling times were determined as 0 h, 2 h, 4 h, 6 h and 8 h. The results showed that relative density values decreased with increase of milling time from 0 h to 8 h, while an increase in porosity values was detected for HNCs. The results also showed that the highest values of hardness and tensile strength were 165 HB and 202 MPa, respectively, in the 8-h milled HNC sample. According to the wear results, the wear rate decreased continuously as the milling time increased. The wear rate of the hybrid nanocomposite sample with 8 h of milling time and a sliding distance of 250 m is 0.0248 mm(3)/m, while the wear rate of the unmilled hybrid nanocomposite sample is 0.0443 mm(3)/m. Therefore, increasing milling time significantly improved the wear resistance of hybrid nanocomposite because of more uniform particle dispersion.

Automated summary

This study investigated the effect of mechanical milling time on the properties of B4C and graphene-reinforced ZA40 metal matrix hybrid nanocomposites. The results showed that increasing milling time led to a decrease in relative density but an increase in porosity. The highest values of hardness and tensile strength were obtained in the 8-hour milled HNC sample. Additionally, increasing milling time improved the wear resistance of the hybrid nanocomposite due to more uniform particle dispersion.