The Role of Copper on the Friction and Wear Performance of Automotive Brake Friction Materials

1. The Role of Copper on the Friction and Wear Performance of Automotive Brake Friction Materials S.H. Sung*, J.J. Lee, J.H. Cha, J.H. Jo Sangsin Brake Corporation S.J. Kim, J.Y. Lee, J.M. Han, Y.C. Kim, H.D. Park Hyundai Motor Company H. Jang Korea University

2. Background • Copper’s feature Copper fiber • High Ductility • High Thermal Conductivity • Proper Melting Point • Low Mohs Hardness Copper powder ▶ Play a role as a solid lubricant for high temperature

3. Objective Investigate the role of cuprous ingredients in friction materials The copper is an essential component in friction materials The contamination of storm water and bay from brake pad wear debris The limitation to the use of copper Current regulation in the United States Development of Cu reduction & Cu-free friction material

4. Current Regulation of Copper 2020 New York 5wt% ↓ Not yet decided New York Washington Rhode Island Oregon 0.5wt% ↓ 2021 Washington California Rhode Island Oregon 5wt% ↓ 2025 California 0.5wt% ↓

5. Cuprous Ingredients Copper Sulfide (CuS) Cupric Oxide (CuO) Copper fiber Copper Powder 8.9 8.2 6.6 4.5 Density (g/㎤)

6. Non-steel Formulation

7. Brake Performance & Wear Test 1/5 scale dynamometer Full scale dynamometer - Standard burnish - Braking temperature range 100~400 - JASO C406-P1 Mode

8. Wear Test Procedure

9. Physical Properties (Effect of the type) Copper fiber

10. Physical Properties (Effect of the amount)

11. Friction Coeff. & Disk Wear Copper free CuS

12. The Change of Friction Coeff. (as a function of deceleration) 2nd effectiveness @ 130kph 0.46 Cu fiber CuS Cu free 0.30

13. The Change of Friction Coeff. (with different amounts of copper fiber) 50kph 100kph 130kph 100kph Fade Effectiveness

14. The Change of Friction Coeff. (with different amounts of cupric oxide) 50kph 100kph 130kph 100kph Fade Effectiveness

15. The Change of Friction Material Wear (with different amounts of copper fiber) Copper fiber 10wt% Copper fiber 5wt% Copper fiber 3wt% Copperfree

16. The Change of Friction Material Wear (with different amounts of cupric oxide) Cupric oxide 10wt% Cupric oxide 3wt% Cupric oxide 5wt% Copperfree

17. Worn Surface Morphology Cu free Copper Fiber 10 wt.% Cupric Oxide 10 wt.%

18. The Change of Friction Coeff. @ 350℃ (with different amounts of copper fiber) Copper fiber 10wt% Copperfree

19. The Change of Friction Coeff. @ 350℃ (with different amounts of cupric oxide) Cupric oxide 10wt% Copperfree

20. Summary 1. Physical property 1) The type and amount of cuprous ingredients showed little effect on the hardness and compressibility 2) Copper fiber showed better thermal conductivity 2. Performance test by the type of cuprous ingredients 1) Copper fiber, powder, oxide showed a mild aggressiveness compare with copper free and sulfide 2) Copper fiber and sulfide improved the friction stability, copper free showed reduction of μ and severe disk wear

21. Summary 3. Performance test with different amounts of copper fiber or oxide 1) Copper fiber amount increases, friction coefficient was increased on the contrary, the friction coefficient was decreased with cupric oxide 2) The friction material containing 10 wt.% of cupric oxide showed improved fade resistance 4. Wear test with different amounts of copper fiber or oxide 1) Copper fiber showed better wear resistance than cupric oxide 2) While increasing the copper fiber amount, total wear increased 3) Cuprous ingredients played an important role in improving friction stability at elevated temperatures

22. Thank you for your attention