Properties of WC–10%Co–4%Cr Detonation Spray Coating Deposited on the Al–4%Cu–1%Mg Alloy

One of the methods of local improvement of the wear resistance of aluminum alloy parts is the deposition of hard tungsten carbide-based coatings on the surfaces subjected to intense external influence. This paper is devoted to the characterization of the WC–10Co–4Cr (wt.%) coating deposited on an Al–4Cu–1Mg (wt.%) alloy by the detonation spray method. In comparison with the common thermal spray techniques like High Velocity Oxygen Fuel (HVOF) or Atmospheric Plasma Spraying (APS), the heat input delivered to the substrate during detonation spray is significantly lower, that is especially important in case of coating deposition on aluminum alloys. The paper presents the results of morphology investigation, microstructure, phase composition, microhardness, and cohesive strength of deposited carbide-based detonation spray coating. Results showed that the coating has a porosity less than 0.5% and the carbide grain refinement down to the submicron size during coating deposition was detected. According to the investigation, the variation of spraying distance from 270 to 230 mm does not influence on the coating microstructure and composition.

The Influence of Powder Characteristics on the Properties of Detonation Sprayed Cr3C2-25NiCr Coatings

Thermal sprayed chromium carbide (Cr3C2)-25% NiCr (Ni-20%Cr) coatings are extensively used in wear resistant applications especially under conditions wherein operating temperatures are likely to be higher than 500°C . The performance of the Cr3C2-NiCr coatings under such conditions depend on a variety of coating properties like the porosity, microstructure, extent of decarburization of Cr3C2 phase and hardness. One of the parameters which affects the above mentioned coating properties is the characteristics of the powder utilized for thermal spraying. In the present study, Cr3C2-25% NiCr powders obtained from four different sources has been utilized to form Cr3C2-NiCr coatings on steel substrates utilizing the detonation spray coating (DSC) system. The Cr3C2-NiCr powders utilized vary from each other in terms of manufacturing route employed (sintered and crushed, pre-alloyed, blended, etc.), particle size distribution, particle shape and even phases present. The influence of each of these powder characteristics on the coating microstructure, porosity, hardness, extent of carbide dissolution and ultimately on coating performance (i.e. sliding and abrasive wear resistance) has been evaluated.