The Reason of the Tungsten Heater Loss in the Aluminizing Process ——Oxidation

Another reason for the large consumption of tungsten heater is oxidation. Tungsten heater oxide is that the wolfram wire would react with oxygen in the air, which could lead to breakage of heating element, thus shortening its life time. Aluminizing for too long can also lead to tungsten wire directly bake surface aluminum layer and the wire become yellow.

In general, the oxidation temperature of heating element is about 850℃, if the cooling is not sufficient after evaporating, the part of wolfram heater that exposed to the air would react with oxygen, causing oxidation. During the process of mass production, the aluminum evaporation is carried out continuously. Before steaming aluminum screen, air should be added into the vacuum vessel, or steaming aluminum screen cannot be moved away. If the heater element cannot be adequately cooled, the amount of oxygen in the air can easily oxidize the heating element. After oxidizing, the effect of heating element would be reduced, thus affecting the efficiency of the coating.

For the oxidation problem, operators can let the heating element to be maximized cooled before opening the leakage valve, which can reduce the chance for high temperature oxidation of wolfram heater. On the other hand, it is required that operators should maintain and inspect equipment of aluminizing regularly, to keep cleanliness. The improvement of the degree of vacuum in deposition process can effectively avoid the heating element to be oxidized at high temperatures, thereby extending the life time of the heater element. In addition, clean fixtures of wolfram heater regularly, do not use dirty fixtures, which would affect the degree of vacuum. The groove of fixtures of wolfram heater should be maintained smooth, to avoid the residual foreign body to damage heating element. Through these measures, it can reduce frequency for operators to switch the heating element, further improve produce efficiency, reduce consumption of materials.

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