Polyimide-based composite coatings for simultaneously enhanced mechanical and tribological properties by polyhedral oligomeric silsesquioxane

• Published in: Tribology international 2022-07, Vol.171, p.107521, Article 107521
• Main Authors: Yu, Chuanyong, Liao, Yuwen, Zhang, Peng, Li, Bin, Li, Shuangjian, Wang, Qiwei, Li, Wei
• Format: Article
• Language: English
• Subjects: Bearing capacity; Coatings; Elongation; Lubrication; Lubrication coating; Mechanical properties; Nanohardness; Organic-inorganic hybrid; Polyhedral oligomeric silsesquioxane; Polyimide; Polytetrafluoroethylene; Tensile strength; Tribology; Wear rate; Wear resistance
• ISSN: 0301-679X; 1879-2464
• DOI: 10.1016/j.triboint.2022.107521

The increasingly harsh service condition of lubricating coatings presents a more pressing demand for improving performance. Herein, octa-amino polyhedral oligomeric silsesquioxane (POSS) were covalently grafted onto polyimide (PI) matrix. The effect of POSS on the mechanical properties of the PI-based composite coatings and the tribological properties of PI/PTFE based lubricating coatings before and after modification were investigated. As expected, compared with the pure PI, the POSS-PI nano-materials exhibited 31.6% and 32.7% enhancements in tensile strength and nano-hardness without discernable decrease in breaking elongation. Additionally, the wear rate significantly decreased by 54.9% with the addition of OPOSS. The enhancement of wear resistance could be attributed to the improved cohesion strength and load-bearing capacity of the PI/PTFE composite coating reinforced by POSS. •Octa-amino POSS with unique cage-like microstructure were covalently grafted onto the PI matrix.•The addition of OPOSS greatly improved the thermal stability, hardness and tensile strength of the PI-based composites.•The wear rate decreased significantly from 1.48 × 10−6 mm3N−1m−1 to 6.67 × 10−7 mm3N−1m−1.•A well-covered transfer film is responsible for the superior tribological performance.