Any solid material will dissolve and adsorb some gases in the atmosphere. When placed in a vacuum, these materials release gases through desorption. The rate of degassing is proportional to the gas content in the material. The gas composition, temperature, and time of desorption vary depending on the material.
Different pumps have different pumping rates for gases of different compositions. When evacuating a vacuum, the first thing to be evacuated is the atmosphere in the container (this gas is quickly evacuated, and at 10-1Pa, the furnace is essentially completely depleted). This is followed by the gas desorbed from the surface of the material, the gas diffused from the interior of the material to the surface, and the gas that permeates through the vessel wall into the vacuum.
Therefore, after the goods enter the furnace, they must be insulated and degassed. This is because the goods will absorb some impurity gases before entering the furnace, and we need to use appropriate heating to allow these gases to desorb from the surface of the goods. Taking stainless steel as an example, in addition to the gases adsorbed on its surface, some gases will also be released from the steel during the continuous heating and insulation process. The presence of these gases often has a significant impact on the purity and color of the film, and also has a significant impact on the adhesion of the film layer.
From the above introduction, you should know why heating accessories are required in vacuum coating machines. In order to achieve the required vacuum environment and deposit high-quality film layers, it is essential to configure heating accessories in the vacuum coating machine chamber.
