Friction body or sliding body formed from composite materials reinforced with fiber bundles and containing a ceramics matrix and process for the production of a friction or sliding body

A process for the production of a friction or sliding body, which comprises:

• providing at least first and second composite materials reinforced with fiber bundles and containing a ceramics matrix;
• forming an outside of the friction or sliding body from the first composite material as a friction layer, and joining the second composite material areally to the first composite material as a supporting body wherein the outer surface having regions of free carbon with a maximum diameter 1.2 mm and said free carbon having a surface area with a total fraction being at most 35% of said outer surface;
• and outer surface having a fine crack structure and substantially no stresses in the vicinity of said outer surface;
• producing the at least first and second composite materials from different fractions of fiber bundles as starting substances, the fractions of fiber bundles being a reinforcing fiber bundle fraction and a matrix fiber bundle fraction having different mean fiber bundle lengths with an overall fiber bundle distribution having a minimum fiber bundle length of fiber bundles incorporated in the composite materials, the minimum lying between mean fiber bundle lengths of the reinforcing fiber bundle fraction and the matrix fiber bundle fraction;
• dimensioning the fiber bundle lengths of the fiber bundles incorporated in the first composite material to be substantially shorter than the fiber bundle lengths of the fiber bundles incorporated in the second composite material;
• and
• producing the first composite material by mixing the two fiber bundle fractions together with a binder, and granulating after the mixing.

A brake disc or brake lining for machinery, aircraft, tracked vehicles, road vehicles, components of sliding bearings and sliding elements, comprising:

• at least first and second composite materials reinforced with fiber bundles and containing a ceramics matrix, said first composite material acting as a friction layer and forming an outside with an outer surface, and said second composite material acting as a supporting body and being joined areally to said first composite material;
• said at least first and second composite materials having different fractions of fiber bundles, said fractions of fiber bundles being a reinforcing fiber bundle fraction and a matrix fiber bundle fraction with different mean fiber bundle lengths and an overall fiber bundle distribution with a minimum fiber bundle length of fiber bundles incorporated in said composite material, said minimum lying between said mean fiber bundle lengths of said reinforcing fiber bundle fraction and said matrix fiber bundle fraction;
• said fiber bundle lengths of said fiber bundles incorporated in said first composite material being shorter than said fiber bundle lengths of said fiber bundles incorporated in said second composite material;
• said fiber bundles of said first composite material having, on average, a distinct alignment perpendicular to said outer surface;
• said outer surface having regions of free carbon with a maximum diameter of 1.2 mm;
• said free carbon having a surface area with a total fraction being at most 35% of said outer surface;
• and
• said outer surface having a fine crack structure and substantially no stresses in the vicinity of said outer surface.