With laser melt injection, metal matrix composite (MMC) layers can be generated on various tools. By using spherical fused tungsten carbide (SFTC) particles as reinforcing material, extremely wear-resistant MMC layers can be produced. However, due to low process speeds, the number of applications for laser melt injection was strongly limited until now. Therefore, a high-speed process for laser melt injection (HSLMI) was developed allowing process speeds up to 100 m/min and an efficient production of tools such as skin-pass rolls, accordingly. Skin-pass rolls are used for setting the final sheet thickness and surface texture. In this paper, new textures for skin-pass rolls generated by HSLMI are presented and characterized. Furthermore, it is studied how the texture of the roll is transferred to the sheet metal. For generating an increased high-low structure, laser ablation was carried out after HSLMI and grinding of the rolls. An analysis of the topography showed that different height differences between SFTC particles and matrix can be set. Furthermore, it was found that all textures were transferred from the roll to the sheet metal.

In order to improve gas turbine performance it is possible to decrease back flow gases in the high temperature combustion region of the turbo machine reducing shroud/rotor gap. Thick and porous TBC systems and composite CoNiCrAlY/Al 2 O 3 coatings made by Air Plasma Spray (APS) and composite NiCrAlY/graphite coatings made by Laser Cladding were studied as possible high temperature abradable seal on shroud. Oxidation and thermal fatigue resistance of the coatings were assessed by means of isothermal and cyclic oxidation tests. Tested CoNiCrAlY/Al 2 O 3 and NiCrAlY/graphite coatings after 1000 hours at 1100°C do not show noticeable microstructural modification. The oxidation resistance of new composite coatings satisfied Original Equipment Manufacturer (OEM) specification. Thick and porous TBC systems passed the thermal fatigue test according to the considered OEM procedures. According to the OEM specification for abradable coatings the hardness evaluation suggests that these kinds of coatings must be used with abrasive tipped blades. Thick and porous TBC coating has shown good abradability using tipped blades.

Laser beam cladding is a versatile method for the deposition of functional surface layers, the generation of prototypes, and the repair welding of components. It is a thermal process characterized by a highly localized energy input. Powder-fed laser cladding is typically done with a CO 2 , Nd:YAG, or diode laser scanned at a speed of 0.3 to 1.5 m/min. The present work investigates the extent to which deposition speed and thermal efficiency can be increased. Using a Nd:YAG laser and high scan rates, functional layers a few tenths of a mm thick are obtained and larger surface areas are processed per unit of time. Paper text in German.

Titanium aluminide shows good potential for lightweight applications at high temperatures, provided various problems are overcome. The primary problem, low-temperature brittleness, can be resolved through a combination of laser cladding and directional solidification. This paper explains how Ti48Al2Cr alloy is applied and how process parameters must be chosen so that directional solidification occurs. This involves the use of FEM simulations, carried out in parallel with experimental work, to determine temperature gradients and cooling rates at the solidification front and in the melt pool and their effect on solidification structures. Paper text in German.