US Patent 9841107 Mechanical seal arrangement having sliding surfaces of different hardness

The invention relates to a mechanical seal arrangement comprising: a rotating slide ring (2) having a first slide surface and a stationary slide ring (3) with a second slide surface which between them define a sealing gap 4, wherein the first and second slide surfaces have different hardnesses, wherein the harder slide surface has a diamond coating (20) and the softer slide surface is produced from carbon composite material, and wherein an average initial roughness Ra1 (of the diamond coating 20) is less than an average initial roughness Ra2 of the slide surface made from carbon composite material.