A Brief Introduction of Tungsten Boat

Tungsten boat is also known as evaporated tungsten boat or coated tungsten boat. It is formed by tungsten sheet through high-pressure tungsten. Nowadays, tungsten boat is widely used in vacuum coating industry and sintering furnace and annealing boat industry. There are many specifications of tungsten boat and their shapes are different.

Tungsten's unique properties, including a melting point of 3410° C, low vapor pressure at elevated temperatures and low coefficient of thermal expansion, make it of value in a variety of high temperature products and processes. First of all, the boat type component is made of tungsten metal. And then connect both ends of the component by wire, and put a low melting point metal in the middle of the concave position. Under the electrify condition, the temperature of tungsten boat would rise to about 2000 degrees, so that the metal can evaporate into gas and deposited on the surface of the workpiece.

Tungsten boat is also widely used as source for evaporation resistance. Its working methods is to make tungsten film into the shape of the boat firstly, then install it in two electrodes. Add materials in the center of tungsten boat, and then energize the electrodes slowly. After the current pass tungsten boat, the tungsten boat will give out the heating power. Low voltage and high current would transfer the heating power to the coating material, when quantity of heat of tungsten boat is higher than the melting point of the coating material, the material would obtain the sublimation or evaporate. But tungsten boat still has some limitations for vacuum coating. The film evaporated by tungsten boat has a low density, and there are a lot of materials cannot be deposited in this way. When tungsten boat evaporating and coating materials, the melting point of the material cannot higher than the melting point of tungsten boat.

Tungsten boat is also widely used in electronics industry, such as kinescope, mirror making, toys, household appliances, mobile phones, electrical enclosure. It has good characteristics for electrical conductivity, thermal conductivity, high temperature resistance, wear resistance, corrosion resistance. In addition, tungsten boat has a high melting point, low saturated vapor pressure and stable chemical properties, so it has been widely used as source for resistive evaporation in vacuum evaporation coating industry. Tungsten boat, as an essential part for vacuum coating equipment, the selection of tungsten boat determines the quality of the coating.

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