Why choose electron beam for vacuum evaporation (EB-PVD)

Substance evaporation process in a vacuum, from the point of view of the evaporation rate classification, divided into slow evaporation process and rapid evaporation process two types, also known as weak evaporation process and strong evaporation process. The evaporation rate refers to the mass of the substance evaporated per unit time per unit area. Substance evaporation rate in a vacuum, the theory is mainly affected by the evaporation of the temperature of the surface and the saturation vapor pressure and other physical properties, but in practice, the evaporation process needs to be considered comprehensively, including the transfer of heat, the diffusion process of the substance, the process of the phase transition on the evaporation of the impact of the evaporation process.

In a vacuum, you want to make the substance evaporate quickly, you need to heat the substance, there are many different heating methods, including electron beams, laser beams, resistive heating, magnetron sputtering and other methods, which is relatively widely used is thebeam of electronsand laser heating methods. Both methods have the advantages of high energy density and controllable melting area. E-beam is easier to engineer and realize compared to laser beam.

At present, the most important application techniques of vacuum evaporation include vacuum evaporation coating technology, vacuum evaporation metallurgy technology vacuum evaporation powder technology, etc. The vacuum evaporation treatment of waste belongs to the application of vacuum evaporation metallurgy technology. The use of vacuum evaporation method to prepare a variety of thin film materials and coatings has been a more mature application of technology. In a high vacuum environment, heating the water-cooled crucible in the material to make it evaporate, the evaporated gaseous material diffusion and condensation to the substrate, thus forming a layer of micron or nano-scale thin films. These films or coatings mostly have optical, electrical and other functional properties, and their thicknesses are mostly at the micron or nanometer level. The evaporation rate of the preparation process is slow, belonging to the slow evaporation process, and the amount of evaporation is easy to control.

When the metal is heated to a certain temperature, the electrons on its surface obtain enough thermal energy to overcome the binding force of the metal surface, thus breaking away from the metal surface to form a free electron cloud. These free electrons under the action of electric and magnetic fields, will move in a certain direction to form an electron beam flow.