METHOD OF GAS CEMENTATION OF LARGE-SIZED ARTICLES Russian patent published in 1994 - IPC

FIELD: coating materials. SUBSTANCE: article is heated during 0.33-0.44 of a period of diffusing holding at carbon potential 0.1-0.2 and is held during 0.32-0.85 of a total holding time at carbon potential 1.2-1.3 and at carbon potential 0.7-0.8. After that the article is cooled during 0.09-0.11 of the holding time at carbon potential 1.2-1.3. At each stage of the process natural gas is fed to a working space through main (0.75-0.80 of total flow rate) and control (0.01-0.25 of the total flow rate) passages. A flow rate of a hydrocarbon mixture and a ratio of air to natural gas are specified at each stage of the process. EFFECT: enhanced reliability. 1 tbl