Patent ID: 8586513

Claim:
Anti-friction coating ( 4 ) for a multi-layered friction bearing ( 1 ) made from a tin-based alloy which, in addition to tin, contains at least one other element from the group comprising antimony and copper as the main alloying element, optionally lead and/or bismuth, and optionally at least one element from a group comprising zirconium, silicon, zinc, nickel and silver, and unavoidable impurities originating from the elements used to produce it, and the proportion of antimony is at most 20% by weight, the proportion of copper is at most 10% by weight, the total proportion of lead and bismuth is at most 1.5% by weight, the total proportion of copper and antimony is at least 2% by weight and the total proportion of zirconium, silicon, zinc, nickel and silver is at most 3% by weight, and tin is present bonded in the form of inter-metallic phases and freely as a tin phase with beta-tin grains, wherein the tin grains with a beta-tin structure have a mean size with at least a value in pm calculated on the basis of the formula K=A/ (S+3*C +O), where K stands for the mean grain size in μm, A stands for a factor, S stands for the proportion of antimony in the alloy as a % by weight, C stands for the total proportion of copper, silver, nickel in the alloy and O stands for the total alloy proportion of lead, bismuth, zinc, other alloying elements and non-metallic particles as a % by weight, and the factor A has the value 50, and the mean grain size denotes the arithmetic mean of the values calculated taking each grain as a geometric mean of the biggest and the smallest dimension of this grain as visible in a grain pattern, and the calculation is repeated to determine the biggest grain perceptible in the pattern through to smaller grains until the sum of the cross-sectional surfaces of the grains used to determine the mean represent 80% of the total cross-sectional surface of all the beta-tin grains, and the tin grains with a beta-tin structure in the tin-based alloy in any event have a mean grain size of at least 2.5 μm.