| 摘要 |
PURPOSE:To carburize in a vacuum furnace the surface of a metal material uniformly to a target value, by analyzing hydrogen gas formed through the decomposition of carburizing gas so as to keep the carbon potential of the furnace atmosphere at a prescribed value. CONSTITUTION:A heating furnace 2 contg. a material 3 to be treated is placed in a vacuum furnace 1. The vacuum furnace 1 and the heating furnace 2 is evacuated to a vacuum by the operation of an evacuation system 7 with an on-off valve 10 opened. Then the material 3 to be treated is heated by means of a heater 14, and a carburizing gas such as methane etc. is charged to the heating furnace 2 from a carburizing gas reservoir 6 with an on-off valve 9 opened. The carburizing gas is decomposed to C and H2, the C carburizing the metal material. The gas in the heating furnace 2 is analyzed to measure the C potential. When the C potential is decreased to a prescribed value or under, the gas in the furnace is discharged once, and methane gas is charged once again to increase the C potential. These operations are repeated to carburize the material to a target value and to diffuse by heating, then the material is cooled, then heated once again and put into an oil reserving section 12 of the vacuum furnace 1 in order to be hardened. |
