Effect of Substrate Temperature on Adhesion Strength of Plasma-Sprayed Nickel Coatings

Neutron Diffraction Residual Strain Measurements of Molybdenum Carbide-Based Solid Oxide Fuel Cell Anode Layers with Metal Oxides on Hastelloy X

“…In the equation (2), the subscripts BA^and BB^refer to the anode layer coating and the substrate, respectively. It is known that the particle temperature upon impact during air plasma spraying can be around 1873 ± 473 K [52]. Thermal stress which was calculated using equation (2) with a temperature change, ΔT = 1573 K and assumed cooling to room temperature, 300 K, and CTE values from Table 2, were consistent with the averaged residual tensile strain and stress values in the anode layers and the averaged residual compressive strain and stress values in the substrate near interface (Fig.…”

Thermal contact resistance between plasma-sprayed particles and flat surfaces

“…On heated or preheated surfaces, these adsorbates/condensates are almost completely vaporized [2,5,7,36], improving splat-substrate contact and greatly reducing the thermal contact resistance at the splat-substrate interface. Prolonged heating of a metallic substrate, however, leads to the formation of an oxide layer [6,37], which may lead to increased thermal contact resistance as the thickness of the oxide layer increases. Prolonged heating of glass did not change the thermal contact resistance significantly, since heating does not promote further oxidation on glass.…”

“…Droplets of molten zirconia, plasma sprayed onto a stainless steel substrate kept at room temperature, splashed and produced fragmented splats, whereas on a heated substrate they formed circular, disk-like, splats with almost no splashing [5]. Since irregular splats produce porous coatings with poor adhesion strength [6], knowing the causes of droplet splashing is of considerable practical importance.…”

“…Raising substrate temperature by the amount done in experiments, though, had relatively little effect on heat transfer; varying thermal contact resistance between the substrate and droplet had a much more significant impact on droplet impact dynamics. The explanation offered [1,6] was that heating the steel surface produces an oxide layer that increases contact resistance. This -more than the increase in temperature -influences impact dynamics.…”

Photographing Impact of Molten Molybdenum Particles in a Plasma Spray

“…Coating properties such as adhesion strength and porosity depend on the dynamics of molten droplet impact. If droplets splash during impact, producing solidified splats that are fragmented and irregular in shape, coatings are porous and do not adhere well (Ref 1,2). Coating material is wasted by droplet splashing because secondary droplets bounce off the surface instead of adhering.…”