Corrosion protection

The LASOX-COAT treatment is used for the selective coating of aluminium surfaces via laser. While the workpiece is under an oxygen atmosphere, the laser is targeted along the surface to be coated. The laser starts to melt the alloy and some particles will vaporise. Together with the oxygen this leads to the formation of an oxygen plasma.

The oxygen plasma – which consists of ionised atoms – and the molten aluminium react to aluminium oxide which now covers the treated surface. The thickness of this corundum layer is typical around 6 to 10µm, while the remolten area is about 100µm thick. The hardness of the aluminium oxide is about 2000HV. The hardness of the remolten zone depends on the alloy, and with Si-containing alloys (Si>8%) the hardness can increase by 50% relative to the original alloy.

The major advantage of this process, says the company, is the complete absence of chemicals. Also, no pores are formed in the aluminium oxide layer.

Silicon helps to grow a thicker but slightly rougher layer and even alloys with more than 20% silicon can be coated with LASOX-COAT. The possibilities for the selective coating are many. While flat surfaces are preferred, round surfaces are also possible. Integration of LASOX-COAT into existing production lines is also planned. The coating is best for wear protection but can also be used to reduce corrosion on a workpiece.