Laser based hybrid techniques for surface coatings

Laser beam build-up welding gains increasing importance for the production of high-performance coatings for applications in surface treatment and remanufacturing. However, the cladding rate is low and the specific running costs are comparatively high, so that potential laser applications remain undeveloped first of all for economical reasons. Against this background, innovative developments aim at combining laser build-up welding and efficient spraying, welding, and heat treating techniques. For large area claddings, laser assisted plasma spraying guarantees as a one-step coating process high deposition rates, completely dense coatings and a strong, metallurgical bonding to the substrate. Furthermore, the sequential combination of laser and plasma build up welding (PTA) is a promising variant for the production of precision parts. Here, the laser beam generates the outer contours of filigree and complex shape, and the plasma gun fills efficiently the inner volume. Finally, the combinat ion of laser cladding and simultaneous induction heating is a solution for the production of up to 65 HRC hard and crack-free metal coatings or composite claddings containing up to 75 % carbide particles. The welding speed reaches up to 10m/min. Examples of application are ceramic coatings on turbine blades, nickel-base coatings on metal forming tools, and repaired tools and molds.