Efficient friction and wear reduction of Al-Si alloy via tribofilms generated from synergistic interaction of ZDDP and chemically functionalized h-BN additives

[Display omitted] •Chemically functionalized h-BN-TBO in ZDDP containing base oil possess excellent dispersibility.•Combined tribological effect of ZDDP and h-BN-TBO on an Al-Si alloy is studied using in situ AFM.•Tribological properties improve significantly due to the synergistic interaction of ZDDP and h-BN-TBO.•Addition of functionalized h-BN with ZDDP promotes formation of protective antiwear tribofilms on Al and Si. Zinc dialkyldithiophosphate (ZDDP) and molybdenum dithiocarbamate (MoDTC) are conventional lubricant additives for reducing friction and wear of metallic components. However, their efficacy for lightweight aluminum (Al)-based alloys is limited due to the wear of soft Al matrix regions. The present work reports significant improvement in the tribological properties of Al-Si alloys (ADC12) under liquid lubricants containing a combination of ZDDP and hexagonal boron nitride (h-BN) nanosheets. In situ monitoring of tribofilm growth, friction, and wear was carried out using atomic force microscopy (AFM)-based measurements. At high temperature (110 °C), experiments were carried out at the Al matrix and Si phase of ADC12 alloy under the lubricant containing ZDDP (1 wt%) and tert-butoxy (TBO) functionalized h-BN nanosheets [(h-BN-TBO), (0.02 mg/mL and 0.05 mg/mL)]. The addition of h-BN-TBO in ZDDP containing lubricant significantly improved the tribological properties due to the synergistic interaction between h-BN-TBO and ZDDP; leading to the formation of lubricious and robust antiwear tribofilms on Si and Al phase regions. A synergistic combination of h-BN-TBO and ZDDP as lubricant additive showed superior performance compared to ZDDP or a combination of ZDDP and MoDTC-based lubricant systems.