Vacuum Carburizing Gas

1.C3H8 as the carburizing gas
C3H8 is rich in “C” source, and early vacuum carburizing has always used propane (C3H8) as carburizing gas. Its characteristics are as follows:
(1) The percolation rate is fast, and high-temperature rapid carburization can be performed.
(2) There is no grain boundary oxide layer in the layered structure.
(3) It is possible to make complex shapes and carburization without through holes.

2. C3H8 carburizing gas dis advantage
(1) The amount of installed furnace increases, the flow rate of carburizing gas increases, the pressure increases, and the carbon black is more serious.
(2) Due to the serious carbon black, the frequency of maintenance is accelerated.
(3) In order to reduce the amount of maintenance and frequency, it is necessary to reduce the amount of furnace loading, resulting in low productivity. For this reason, vacuum carburizing stays in the application of special fields and special parts, and it is difficult to promote and popularize.

3. Characteristics of C2H2 as carburizing gas
The surface carbon concentration of methane is as low as 0.2%, and there is basically no carburizing ability; the surface carbon concentration of acetylene is up to 1.4%, the carburizing ability is the strongest; the propane and ethylene are the same, the carburizing ability is middle, and the same carburizing layer is deep. When carbonizing with acetylene, the carbon concentration is 0.1% higher. The carbon transport capacity or the enrichment rate (g/m2·h) is also the same, methane 2g/m2·h, propane and ethylene are 120g/m2·h and 130g/m2·h, carbon transport of acetylene The largest, close to 150g/m2·h.