Effect of AA 6351-ZrB2 in-situ composition on dry sliding wear performance at elevated temperatures

Abstract The dry sliding wear behavior of AA 6351 aluminum alloy composites in situ reinforced with synthesized ZrB2 at elevated temperatures were investigated aiming at practical engineering applications. A low-cost, reactive system of KBF4 and K2ZrF6 was reacted with the molten AA 6351 matrix at 850°C to form ZrB2 particles within the AA 6351 matrix. Uniaxial Strength and Elastic Moduli of ZrB2–SiC Composites with Various ZrB2 Contents (0 wt.%, 3 wt.%, 6 wt.%, and 9 wt.%) at 100°C and 200°C according to the method of the ASTM G99-95a standard. The addition of ZrB2 increased wear resistance dramatically, and the 9 wt. % ZrB2 composites instead of their unreinforced counterpart at 100°C and 200°C and/or which are 45–38% lower than that of unreinforced alloy. After the solutionizing and artificial aging, the wear resistance can be additionally increased by approximately 15–20% due to the precipitation hardening (fine Mg2Si particles formation) and a stronger matrix-particle interfacial bonding. Reinforced composites exhibited enhanced load-bearing capacity, increased thermal stability, decreased adhesive and abrasive wear. The wear resistance observed in these composites is consistent with strong scientific theory that ceramic particle reinforcement improves mechanisms of load transfer and crack deflection, suggesting that AA 6351-ZrB2 composites are well suited to aerospace brake system and automotive friction lining applications, where improved wear resistance translates to service life extension and reduced maintenance costs. Optimizing the size and uniformity of the ZrB2 particles and the process conditions could yield more significant benefits for high-temperature wear-sensitive applications.