Silicon carbide abrasive particles having multilayered coating
AssigneeUnited Technologies Corporation
InventorsDavid A. Condit, Harry E. Eaton
Life of this patent
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Abstract
Ceramic particles useful as abrasives in a metal matrix layer are described. The particles are coated with an oxide monolayer and a metal duplex layer. Preferably, the particles are silicon carbide; the oxide monolayer is aluminum oxide, and the metal duplex layer is a nickel-boron alloy over pure nickel.
Claims9
Metal coated ceramic abrasive particles in the range of about 25 to 1,250 microns, the particles having a duplex metal coating thereon which comprises a first metal coating layer which substantially encapsulates each particle and is selected from the transition metals, high melting temperature noble metals, and alloys thereof;
- and a second metal coating layer which substantially encapsulates the first coating layer, and is selected from said transition and noble metals and alloys thereof which contain a melting point depressant in sufficient quantity so that the second metal layer melts at a temperature less than the melting temperature of the first metal layer, wherein the second metal layer is capable of significant diffusion into nickel and cobalt base superalloys when heated near its melting temperature and forms no deleterious phases on diffusing into said superalloys, and the second metal layer wets the first metal layer when the second metal layer is molten.
Ceramic particles useful as a dispersoid in a metal matrix, each particle having a multiple layer coating thereon which comprises an oxide coating layer resistant to diffusion or dissolution with the ceramic;
- and a duplex metal coating layer over the oxide coating layer, the duplex metal coating layer comprising first and second metal layers, the first metal layer having a melting temperature above about 1,100.degree. C., and resistant to diffusion or dissolution with the oxide coating layer, and the second metal layer having a melting temperature less than about 1,100.degree. C., said second metal layer wetting the first metal layer when molten.
An abrasive layer on the tip surface of a gas turbine engine blade, the layer containing spaced apart ceramic particles in a metal matrix, wherein the ceramic particles are each sinter bonded to the blade surface and the matrix fills in the regions between the particles, wherein each particle has an oxide monolayer and a duplex metal coating layer thereon, wherein the oxide monolayer does not react with the ceramic and substantially encapsulates each particle;
- and the duplex metal coating layer comprises first and second metal layers, the first metal layer not reacting with the ceramic and substantially encapsulating each particle, and the second metal layer diffused with the blade surface.
Silicon carbide particles having a size in the range of about 25-1,250 microns, and having a 5-25 micron thick layer of aluminum oxide, a 2-8 micron layer of nickel over the aluminum oxide coating, and a 2-8 micron layer of nickel-boron over the nickel coating, the nickel-boron coating containing between 1-5 weight percent boron.
Dependencies are inferred from the claim text.