Why vacuum coating surface cleaning use sand blasting?
The adhesion of the coating has a lot to do with the condition of the surface of the coating, and not on any surface of the coating adhesion is very good. Sand blasting as a vacuum coating of a pre-treatment method, is to ensure that the coating in some bad surface adhesion, such as the surface of the oxide layer, the surface of corrosion, grinding or polishing poor surface.
The oxidation layer and corrosion layer on the workpiece surface have poor bonding strength with the matrix, which is easy to peel off under the action of temperature change stress.
In the process of coating heating, some oxidation layer and corrosion layer gradually peeling, no peeling oxidation layer and the layer of mystery is covered by the coating, in the coating process, by the coating stress, some oxidation layer and corrosion layer also peeling.After the coating is finished, the oxidation layer and corrosion layer without peeling exist between the substrate and the coating. During the coating cooling process, thermal expansion and cold shrinkage stress caused by temperature changes may peel off the coating together.This part of the coating that does not fall off is attached to the substrate by the oxide layer or corrosion layer, and its adhesion force with the substrate is very poor, in the workpiece use process, this part of the coating falls off first.The failure of the workpiece spreads gradually from here, and eventually leads to the failure of the whole workpiece.Peeling of oxidation layer and corrosion layer in the process of heating, coating and cooling will affect the structural characteristics and adhesion of the coating layer, and ultimately lead to a sharp decrease in the coating life of the workpiece.
Sandblasting can be in the vacuum coating before the surface of the workpiece oxidation layer, corrosion layer and other grinding off, so that the tool to obtain consistent surface quality, to ensure coating adhesion, reduce the discrete performance of coating tool in the process of use, that is, to obtain a more stable cutting ability. Comparison of the surface condition of a workpiece before and after sandblasting. Sandblasted workpiece surface fine, uniform color and luster.
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