A valve seat formed within an aluminum engine component includes a valve seat surface machined within the aluminum engine component, a layer of copper alloy material laser clad onto the valve seat surface of the aluminum engine component, the layer of copper alloy material having a thickness of less than 2.0 millimeters, and a layer of copper alloy/tool steel carbide material laser clad onto the layer of copper alloy material, the layer of copper alloy/tool steel carbide material having an average thickness of less than 0.5 millimeters, wherein the layer of copper alloy/tool steel carbide material has an outer surface that is machined to a final valve seat profile.

A spray coating film has a first spray coating film formed on a surface of an aluminum substrate and a second spray coating film formed on a surface of the first spray coating film. In the first spray coating film, an inorganic material with a layered crystalline structure is dispersed in a Ni-based alloy material, and an area ratio of the inorganic material is in a range from 40% to 80% relative to the sectional area of the first spray coating film. The second spray coating film is a porous film composed of ZrO.sub.2—SiO.sub.2 based ceramic containing 30% to 50% by mass of SiO.sub.2, and the second spray coating film has an area ratio of pores of 30% to 80% relative to the sectional area of the second spray coating film.

A spray coating film has a first spray coating film formed on a surface of an aluminum substrate and a second spray coating film formed on a surface of the first spray coating film. In the first spray coating film, an inorganic material with a layered crystalline structure is dispersed in a Ni-based alloy material, and an area ratio of the inorganic material is in a range from 40% to 80% relative to the sectional area of the first spray coating film. The second spray coating film is a porous film composed of ZrO.sub.2—SiO.sub.2 based ceramic containing 30% to 50% by mass of SiO.sub.2, and the second spray coating film has an area ratio of pores of 30% to 80% relative to the sectional area of the second spray coating film.

A sliding member of the present invention includes a coating on a base material. The coating contains hard metal particles and corrosion-resistant metal particles that have hardness lower than that of the hard metal particles. The hard metal particles contain particles that have at least Vickers hardness of 600 Hv or higher. The corrosion-resistant metal particles are made of at least one kind of metal selected from the group consisting of copper (Cu), cobalt (Co), chromium (Cr), and nickel (Ni), or are made of an alloy containing said metal. The coating has a cross section in which the hard metal particles are dispersed in an island manner in a particle aggregate of the corrosion-resistant metal particles and in which an area ratio of the corrosion-resistant metal particles is 30% or larger. Thus, corrosion of the hard metal particles in the coating is prevented, whereby the sliding member maintains wear resistance for a long time.

A sliding member of the present invention includes a coating on a base material. The coating contains hard metal particles and corrosion-resistant metal particles that have hardness lower than that of the hard metal particles. The hard metal particles contain particles that have at least Vickers hardness of 600 Hv or higher. The corrosion-resistant metal particles are made of at least one kind of metal selected from the group consisting of copper (Cu), cobalt (Co), chromium (Cr), and nickel (Ni), or are made of an alloy containing said metal. The coating has a cross section in which the hard metal particles are dispersed in an island manner in a particle aggregate of the corrosion-resistant metal particles and in which an area ratio of the corrosion-resistant metal particles is 30% or larger. Thus, corrosion of the hard metal particles in the coating is prevented, whereby the sliding member maintains wear resistance for a long time.

An engine valve having a shaft portion and a head portion expanding in diameter like a head at an edge of the shaft portion, and being to open and close a port provided in a cylinder head, wherein the head portion has a head front surface on a bottom side facing a combustion chamber side, a head rear surface on a top side facing the port side, and an outer peripheral surface of the head portion formed between the head front surface and the head rear surface, and the head portion is provided a mirror-finished mirror portion, and the head portion is provided a mirror-finished mirror portion on the entire area of the head front surface exposed to the combustion chamber and the entire area of the outer peripheral surface exposed to the combustion chamber.

An engine valve having a shaft portion and a head portion expanding in diameter like a head at an edge of the shaft portion, and being to open and close a port provided in a cylinder head, wherein the head portion has a head front surface on a bottom side facing a combustion chamber side, a head rear surface on a top side facing the port side, and an outer peripheral surface of the head portion formed between the head front surface and the head rear surface, and the head portion is provided a mirror-finished mirror portion, and the head portion is provided a mirror-finished mirror portion on the entire area of the head front surface exposed to the combustion chamber and the entire area of the outer peripheral surface exposed to the combustion chamber.

Provided are a cladding alloy powder that can increase the wear resistance of a cladding alloy to be deposited and a counterpart member adapted to contact the cladding alloy, and a method for producing an engine valve using the cladding alloy powder. The cladding alloy powder includes 0.2 to 0.5 mass % C, 30 to 45 mass % Mo, 15 to 35 mass % Ni, 0.5 to 2.0 mass % Zr, and a balance including Co with unavoidable impurities. The method for producing an engine valve includes melting the cladding alloy powder, and cladding a valve face portion of an engine valve adapted to contact a valve seat with the melted cladding alloy powder.

Provided are a cladding alloy powder that can increase the wear resistance of a cladding alloy to be deposited and a counterpart member adapted to contact the cladding alloy, and a method for producing an engine valve using the cladding alloy powder. The cladding alloy powder includes 0.2 to 0.5 mass % C, 30 to 45 mass % Mo, 15 to 35 mass % Ni, 0.5 to 2.0 mass % Zr, and a balance including Co with unavoidable impurities. The method for producing an engine valve includes melting the cladding alloy powder, and cladding a valve face portion of an engine valve adapted to contact a valve seat with the melted cladding alloy powder.

With a poppet valve using a coolant, maximum combustion efficiency is realized by adjusting relative values of a heat insulation effect and a heat dissipation effect. From the inside of a head portion (14) to a stem portion (12) of a hollow poppet valve (10) a heat insulating space (S1) and a cooling portion (S2) loaded with a coolant (19), separated from each other by a partition (15), are formed. By properly setting an installation position and a vertical length of the partition (15) according to a type of vehicle for which the valve is used, appropriate heat insulation effect and heat dissipation effect are obtained. Further, by the partition (15), mechanical or thermal strength of the poppet valve in which the heat insulating space (S1) and the cooling portion (S2) are formed is increased.