In situ microscopic study of tribology and growth of ZDDP antiwear tribofilms on an Al–Si alloy

• Published in: Tribology international 2020-11, Vol.151, p.106419, Article 106419
• Main Authors: Mittal, Prashant, Maithani, Yogita, Singh, Jitendra Pratap, Gosvami, Nitya Nand
• Format: Article
• Language: English
• Subjects: Alloy development; Aluminum base alloys; Aluminum oxide; Antiwear tribofilm; Atomic force microscopy; Coefficient of friction; Ferrous alloys; Friction; High temperature; Lubricant additive; Nonferrous alloys; Silicon; Sliding; Tribology; Wear; ZDDP
• ISSN: 0301-679X; 1879-2464
• DOI: 10.1016/j.triboint.2020.106419

Zincdialkyldithiophosphates (ZDDPs) form protective antiwear tribofilms but the growth mechanism and their contribution to friction on non-ferrous alloys are not well understood. Using a recently developed in situ AFM technique, we monitor the growth of ZDDP based tribofilms, friction, and wear, over Al matrix and Si phase of ADC12, sliding against a nonferrous alumina probe. Sliding tests performed at elevated temperature (110 °C), simultaneously over Al and Si phase, reveal tribofilm growth on both Al and Si regions without noticeable wear. However, the tribofilm thickness, density, and coefficient of friction on the Si phase are higher than on the Al matrix. Significant wear and increase in the coefficient of friction was observed when sliding within the Al matrix region alone. •ZDDP tribofilm growth on Al–Si alloys is studied at the microscale.•In situ AFM reveals correlation between friction and tribofilm growth.•Tribofilm grows thicker and denser on Si phase than Al matrix.•Frequent wear of the Al matrix inhibits tribofilm growth.