Pure aluminum coatings deposited by a high velocity oxyfuel (HVOF) process have been produced and studied. A simple design-of-experiment (DOE) was used to assess the effect of two deposition parameters, the spray distance and oxygen-to-fuel ratio, on relevant coating properties. Porosity, surface roughness, and micro-hardness of the coatings were measured as responses to changes in the DOE parameters. The results indicated that these three properties of the aluminum coatings were normally insensitive to spray distance. Oxygen-to-fuel ratio, by flow, did appear to affect the porosity level of the coatings. Some post-coat processing of the aluminum coatings and minimization of nozzle loading are discussed.

The JET KOTE coating process is a high-velocity oxyfuel process used to form coatings of high quality and density. Coatings can be produced from carbide-bearing composite, alloyed metallic, nonmetallic, intermetallic, or pure metal powders. The coatings are used for wear and/or corrosion resistance in the aircraft, chemical, oil and gas, and steel manufacturing industries, as well as in other demanding fields. Many applications, especially in the petrochemical field, require thick coatings. Coatings must be applied economically, without loss of integrity. Thickness limitations are thought to be due to coating stress, which results in coating cracks and/or delamination and ultimately in failure. This paper examines the effects of operating parameters and techniques on the physical properties of thick coatings produced from Stelcar JK117, a tungsten carbide/17 % Co composite powder. Special emphasis is placed on those parameters which are economically desirable to achieve high deposition rates.