Vacuum furnace atmosphere

Vacuum furnace atmosphere in the design process, first of all, must guarantee the sealing of the furnace section better vacuum furnace atmosphere furnace shell adopts continuous weld, oven door and doorcase contact surface machining, all holes have a sealing device, a former room and room, after the fire shade and explosion-proof device. The atmosphere of the furnace is evenly distributed and the circulating fan is installed. Using a large – section resistive plate or radiation tube as a heat source, work under the atmosphere of carburizing, the surface of the electric heating body will be carbon, and the large cross-section resistive plate will be easy to clear the carbon and prolong the service life.

The furnace lining material has the ability of anti-reduction and anti-carburizing, and the thickness of the furnace lining is thicker than that of ordinary resistance furnace. The reason of the high temperature atmosphere is that the air thermal conductivity of the furnace is larger than that of air. In the reducing atmosphere, the thermocouple should be polluted and the output power is reduced, so that the actual temperature is greater than the indicated temperature. Therefore, controlled atmosphere furnace domestic demand using large diameter thermocouple, heat resistant steel casing protection casing hot end closed, the cold end must be open, make the shielding gas can escape, at the same time to the thermocouple calibration on a regular basis.

The use of controlled atmosphere furnace matters needing attention in order to keep furnace atmosphere composition undisturbed, need to maintain positive pressure controlled atmosphere furnace, furnace gas pressure higher than atmospheric pressure workshop general dozens of PA to hundreds of PA. Therefore, in the process of furnace work, there is often a controlled atmosphere through the oven door, sand seals and other untight, the need to continuously add a controllable atmosphere to the furnace. The use of pure theoretical method to determine the atmosphere consumption can only serve as a reference.

The empirical formula and data should be analyzed with the actual comparative analysis before it can be used as the basis for determining the capacity of controllable atmosphere furnace. The controllable atmosphere has combustible gas, special attention should be paid to prevent explosion and poisoning accidents. When the production is resumed after each stop, the air in the furnace must be used first. The amount of nitrogen will be equivalent to about 4, 5 times the furnace volume, and the nitrogen will be released to the control atmosphere in the furnace.