The use of thermally sprayed coatings to improve wear and corrosion resistance of industrial components has been found to be an effective and viable choice. Coatings based on several materials can be used for such applications, including situations when they are combined, using distinct deposition methods. The analysis for choice of the ideal coating and application process should generally take into account both coating performance and cost. In this work a comparative study of three commercial coating materials is performed. The used coating materials are High Chromium (HCr), High Chromium + 420 Stainless Steel and 420 Stainless Steel + 1080 Carbon Steel wires applied by Electric Wire Arc Spaying. The obtained coatings are tested for wear (ASTM-G-65-91 rubber wheel test) and corrosion (ANSI/ASTM-B117 and Electrochemical Measurements). Coatings microstructure, microhardness and adhesion (ASTM-C633-85) are also evaluated.

Nowadays the use of light weight materials increases rapidly. Owing to growing requirements regarding material properties and corresponding production costs new material designs and novel production concepts are needed. The low density of aluminium and its alloys is accompanied by lower Young’s modules and lower strengths compared to steel. These disadvantages regarding to stiffness and strength can be overcome by using a composite material consisting of aluminium and embedded endless reinforcing elements. In this work a novel technology based on the thermal spraying process to manufacture endless reinforcing elements for extrusion molding of Al-profiles will be discussed. A specific handling system for arc-spraying Al-alloys onto steel wires has been developed. The influence of the coatings materials and coating parameters on the subsequent extrusion moulding process has been studied.

One of the most effecting parameters for the wire arc spraying with the regard to the properties of the sprayed coatings is the flow characteristic of the atomizing gas. Depending on the nozzle inner contour at the entrance of the torch, the atomizing gas is emanating the nozzle as a non-adjusted supersonic gas jet, either under- or over expanded. Thus, a convergent-divergent nozzle with a bell-shaped divergent exit is designed in order to generate a completely expanded atomizing gas flow inside the nozzle without any shock nodes in the emanating gas jet. The influence of the flow characteristic of the atomizing gas (air) on the droplet velocity is investigated by Laser- Doppler-Anemometry measurements. The coating quality is characterised with regard to the surface roughness and porosity.

In order to find the size and shape of particle detachments in the wire-arc spraying system, it is required to find the shear force on the electrodes (wire-tips). To solve the gas flow problem, the system was divided into two regions: (1) upstream and (2) downstream of the nozzle exit. In region 1, the axisymmetric turbulent gas flow is numerically solved and compared to its approximate analytical solution. In the second numerical region, which includes the tips of the two wires, shear force on the electrode surfaces is evaluated from the gas flow velocity profile adjacent to the electrodes. The gas flow in these regions is solved using the FLUENT software. Abstract only; no full-text paper available.