AHC Oberflächentechnik in Germany has developed a novel laser-based method for oxidising aluminium surfaces without using chemicals. The Lasox-Coat treatment process can coat components selectively using a laser to protect them against wear and corrosion. A pilot plant is located in the French subsidiary Faulquemont; the process will enter serial production soon.
The laser heats the workpiece under oxygen to form an oxygen plasma. The oxygen plasma – which consists of ionised atoms – along with molten aluminium react to form aluminium oxide, which coats the treated surface.
The thickness of this corundum layer is typically around 6 to 10µm, while the re-molten area is about 100µm thick. The hardness of the aluminium oxide is approximately 2,000 HV. The hardness of the re-molten zone depends on the alloy used – with Si-containing alloys (Si>8 per cent) the hardness can increase by 50 per cent relative to the original alloy.