Wear protection layer for piston rings, containing wolfram carbide and chromium carbide
AssigneeFederal-Mogul Burscheid GmbH
InventorChristian Herbst-Dederichs
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AssigneeFederal-Mogul Burscheid GmbH
InventorChristian Herbst-Dederichs
Estimating the term…
The invention relates to a wear protection layer for piston rings in internal combustion engines consisting essentially of chromium carbides, wolfram carbide, chromium and nickel. The wear protection layer is formed from a mixture of powders in which the first powder consists of at least the alloy components chromium carbide, chromium and nickel, in the form of an agglomerated and sintered powder, and which has not been subjected to any secondary heat treatment that would make the powder brittle, such as plasma refinement, the carbides in the powder having an average diameter of essentially not more than 3 μm. A second powder, also in the form of an agglomerated and sintered powder, contains wolfram carbide and is applied to at least one peripheral surface of the piston rings by thermal injection, so that two distinctive coating areas are produced in the wear protection layer. A first area, predominantly rich in chromium, and a second area, mainly rich in wolfram carbide are formed.
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.
Dependencies are inferred from the claim text.