Patent ID: 7001670

Claim:
Piston ring for internal combustion machines, with a protective layer against wear applied to at least one peripheral area of the piston rings by means of thermal spraying the protective layer, the protective layer consisting essentially of chromium carbide in phases, tungsten carbide in phases, chromium and nickel, characterized by the fact that the protective layer is formed prior to thermal spraying by a mixture of a first powder and a second powder, wherein the first powder exists as agglomerated and sintered powder made out of at least the alloy components chromium carbide, chromium and nickel, which has not experienced any subsequent embrittling heat treatment, and wherein the chromium carbide in the first powder has a mean diameter grain size smaller than 3 μm, and the second powder comprises an agglomerated and sintered powder containing tungsten carbide, whereby the protective layer as applied by thermal spraying results in a first area developed by the first powder in which phases of chromium carbide are suspended in a chromium and nickel matrix and a second area developed by the second powder in which phases of tungsten carbide are suspended in a matrix, the first and second areas being separated by a discrete boundary.