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Automotive brake lining materials are complex composites consisting of numerous ingredients allowing for their optimal performance. Since regulations are increasingly limiting Cu content in brake pads and Cu exhibits extremely high thermal conductivity, graphites being excellent heat conducting materials themselves, are often considered for use as potential Cu replacement. This paper surveys the role of two types of carbons (Superior Graphite) with high thermal conductivity but different mechanical properties and morphology: the so-called i) purified flake graphite (PFG) and the ii) resilient graphitic carbon (RGC). A successful “high-end” commercial low-metallic brake pad was re-formulated (SIU Carbondale) by removing of over 20 wt. % of Cu and replacing it with a cocktail of ingredients including 15 wt. % of these two graphite types (RGC and PFG).

Friction interaction between brake materials sees a rise in temperatures of over 1000°C contributing to thermal fade of brakes and deterioration/cracking of rotors. Various microstructural features like graphite, ferrite, and pearlite could influence the thermal properties and related friction performance of the brake materials. Even more relevant impact on thermal properties of rotors can be expected after coatings or surface treatments. The primary purpose of this research is to identify the impact of microstructure and surface treatment on the thermal properties of four types of gray cast irons subjected to modified (when compared to their current industrial production) manufacturing processes. These rotors were marked as A (ASTM A48, C30), B (ASTM A48, C20), C (ASTM A48, C30), and D (JIS G5501, FC150), respectively [1, 2].