Laser cladding offers several advantages as low dilution, low thermal influence and distortion of the components and a fine microstructure due to the high cooling rate. Nevertheless the set of laser cladding in the industrial production is nowadays limited to few applications, as the efficiency of laser sources is still too low and the running costs are too high. The absorption behaviour of metal surfaces, as for example steel, towards diode laser (up to approx. 42%) is very high compared to Nd:YAG (approx. 35%) and CO 2 -Laser sources (approx. 11%), so that some benefits can be expected. One of the disadvantages of diode laser was the low intensity and the difficulty to couple it in a fibre. The development of the last years reached to overcome these boundaries. High power diode lasers are nowadays available till 6 kW and can be coupled in fibres, allowing an easier processing. Investigations regarding laser alloying with high power diode laser confirm the appreciable reliability of this laser class. In order to improve efficiency of laser surface processing the hybrid process plasma-augmented-laser-cladding (PALC) with an Nd:YAG laser source was presented and confirmed that due to the pre-heating of the powder through the plasma transferred arc and the activation of the metallic surface a higher processing velocity (factor three) and efficiency could be reached by summing only one third of the energy with a PTA-equipment. Further more when processing with higher velocity the energy loss due to conductivity decreases so that a further positive increase of efficiency can be depicted. The suitability of fibre coupled high power diode laser for PALC hasn’t yet been investigated, even if the set of this laser type would be very advantageous. In this paper investigations regarding the process design and the necessary set up of the hybrid PALC-process with a 3 kW fibre coupled high power diode laser and wire coating metal are reported.

This paper presents process development efforts aimed at exploiting the benefits of both the electric arc-spray technique and the High Velocity Oxygen Fuel (HVOF) technique. This so-called hybrid process offers the benefits of using wire stock and high deposition rates of an electric arc-spray gun combined with the higher coating densities obtained using a HVOF gun. Various configurations starting from a single wire arc to 4-wire arc in combination with HVOF have been investigated. Experiments with single material wires to multi-material wire combinations have also been investigated. The feed rates of individual electric arc wire pairs and HVOF powder/wire are controlled independently allowing the creation of functional gradient materials (FGM). This gun has been used to create alloys as well as patterned deposits of different materials. The ability to create in-situ alloys and patterned deposits with excellent quality has been demonstrated.

The aim of this study is to find a coating that can improve the wear resistance of bushings and sleeves used in continuous hot-dip galvanizing facilities. In the experiments, a number of wear-resistant alloys and their carbide composites are applied to stainless steel substrates by plasma transferred arc (PTA) surfacing and the resulting deposits are characterized based on XRD and SEM analysis, microhardness measurements, and pin-on-disk sliding wear tests conducted in a molten Zn-Al bath at 470 °C. Changes in microstructure during solidification are discussed and correlations are made with phase composition, hardness, wear behavior, and suspected wear mechanisms. Paper includes a German-language abstract.

The processing of frozen foods places high demands on the strength and edge retention of knives, which are typically made of chromium steels due to their corrosion resistance. In meat processing, in addition to cutting, the knives also assume a transport function, where enormous bending forces can occur. A trade-off between strength and ductility is thus required when choosing a material and heat treatment. This paper describes the implementation of a path-controlled build-up welding system for complicated flat contours and the special properties of a newly developed corrosion-resistant powder optimized for knife edges. Field tests indicate that, with the plasma transferred arc welding process and new powders, service life can be extended by a factor of five. Paper text in German.