To obtain an engine valve in which the wear resistance in the face part is improved and attack to mating parts is reduced by precipitating carbides of specified grain size into the surface layer part of the face part of an engine valve composed of a heat resistant steel.
An engine valve 1 provided with a face part 1a is arranged on the inside of a high frequency heating coil 3 arranged in a decarburizing vessel 2. The inside of the decarburizing vessel 2 is evacuated by a vacuum pump, and after that, gaseous propane or the like is fed thereto from a feed port 6. A high frequency AC electric current is made to flow through a high frequency heating coil 3 from a high frequency generator 7, while the face part 1a of the engine valve 1 is locally heated, proscribed voltage is applied thereto from a plasma power source 4, and carbon plasma is generated on the inside of the carbonizing vessel 2. The face part 1a of the engine valve 1 is subjected to plasma cardurizing treatment. Carbides in which the grain size lies in the range of 0.3 to 5μm are precipitated into the surface layer part of the face part 1a. This carbides are precipitated preferably in the range from the topmost surface of the face part 1a to a depth of 50μm.
| JP5317552 | Rolling dice |
| JP2005214038 | ROTARY COMPRESSOR |
MIYAMOTO TAISUKE
SUZUKI YOSHIHISA
