Industrial-Scale Evaluation of Zinc–Iron and Tin–Iron Alloy Powders for High-Performance Copper-Free Brake Applications
Tribology Transactions, vol.69, no.4, pp.968-982, 2026 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 69 Issue: 4
- Publication Date: 2026
- Doi Number: 10.1080/10402004.2026.2668081
- Journal Name: Tribology Transactions
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Applied Science & Technology Source, Chemical Abstracts Core, Compendex, INSPEC, Engineering Source (EBSCO), Materials Science & Engineering Collection (ProQuest), Pharma Collection (ProQuest), Technology Collection (ProQuest)
- Page Numbers: pp.968-982
- Keywords: Cu-free brake pad, Mechanical alloying, tribological performance, zinc–iron and tin–iron alloy powders
- Karadeniz Technical University Affiliated: Yes
Abstract
Copper (Cu) has long been used in brake friction materials due to its high thermal conductivity and stable friction behavior; however, environmental concerns have driven the development of Cu-free alternatives. In this study, iron–zinc (Zn-Fe) and iron-tin (Sn-Fe) alloy powders were investigated as potential substitutes for Cu in brake pad formulations. Zn-Fe and Sn-Fe–powders were produced via mechanical alloying, and their performance was compared with a Cu-containing formulation. The developed brake pads were characterized in terms of porosity, hardness, thermal conductivity, and tribological behavior using a Chase test. The results showed that the Zn-Fe-containing sample (ZF10) exhibited the highest hardness (104.7 HRM) and superior wear resistance, with the lowest weight loss (2.30%), compared to the Cu-containing sample (CO10, 3.15%) and the Sn–Fe sample (SF10, 3.86%). In addition, ZF10 demonstrated the highest average coefficient of friction (0.515), indicating improved friction performance. Although the Cu-containing sample showed the highest thermal conductivity (5.65 W/mK), the Zn-Fe and Sn-Fe systems provided stable friction behavior and good fade resistance at elevated temperatures. These findings indicate that Zn-Fe intermetallic phases significantly enhance wear resistance and friction stability, while Sn-Fe systems offer acceptable performance within Cu-free formulations. Overall, Zn-Fe alloy powders, in particular, emerge as promising and environmentally friendly alternatives to Cu for next-generation copper-free brake pad applications.