US 2007/0261663 A1 · Thermal oxidation protective surface for steel pistons

Abstract

A piston (120) and method for making a piston (120) for a fuel-injected diesel engine adapted to withstand the damaging effects of fuel injection plume-induced oxidation in the regions of the piston bowl (134) and rim (130). The surfaces of the piston crown (126) targeted by the fuel injection plume (138) are first coated with a corrosion-resistant and oxidation-resistant composition applied as a slurry or by a thermal spraying technique, such as HVOF or plasma spraying. Thereafter, a high energy industrial laser beam irradiates the as-sprayed coating to increase its density, while simultaneously reforming its microstructure so as to fuse, alloy, and materially bond the coating material with the underlying steel substrate, thereby resulting in a durable protective surface for the steel piston crown (126).

Claims21

Dependent claims

A method for improving the corrosion resistance of a piston crown for an internal combustion engine, said method comprising the steps of:

providing a piston having a crown presenting an exterior crown surface;
preparing a coating material consisting essentially of a corrosion-resistant and oxidation-resistant composition;
applying the coating material to the piston crown such that the coating material adheres to the crown surface having an as-applied microstructure and an as-applied porosity less than 100% full material density;
and irradiating the coating with a high energy laser beam to increase the density of the coating while simultaneously reforming the microstructure and creating a material bond between the coating and the crown surface.

1 more element

A method for operating a steel piston in a fuel-injected diesel engine, said method comprising the steps of:

providing an engine cylinder having a cylinder head;
providing a piston having a crown including a generally annular rim and a concave bowl set below the rim, the interface between the rim and the bowl forming a generally annular lip;
reciprocating the piston in the cylinder toward and away from the cylinder head;
forcibly discharging liquid fuel into the cylinder and toward the lip of the piston crown;
combusting the fuel adjacent the lip of the piston crown;
and said step of providing a piston including altering the surface composition of the lip of the piston crown by applying a coating material consisting essentially of a corrosion-resistant and oxidation-resistant composition to the lip having an as-applied microstructure and an as-applied porosity less than 100% full material density, and irradiating the coating with a high energy laser beam to increase the density of the coating while simultaneously reforming the microstructure and creating a material bond between the coating and the lip.

3 more elements

Dependencies are inferred from the claim text.

Thermal oxidation protective surface for steel pistons

Life of this patent

Thermal oxidation protective surface for steel pistons

Life of this patent

Abstract

Claims21