| 摘要 |
Gas for the cementation of ordinary or chromium steel is produced by removing from producer gas, water gas or a gaseous mixture containing carbon monoxide and hydrogen, substantially all the carbon dioxide and water vapour contained therein by passing the gas over a column of carbon raised to a temperature higher than the cementation temperature, i.e. above 900 DEG C., and adding to the treated gas a small proportion not exceeding 12 per cent of a saturated aliphatic hydrocarbon. The column of carbon may be heated to the desired temperature by an electric heating device employing rings of silicon carbide or a resistance of an iron-chromium aluminium alloy. In an example the gas used contains 30-50 per cent of carbon monoxide, 10-50 of hydrogen, the rest nitrogen and either 3-12 per cent of methane and ethane or 1-6 of butane and propane. |
