There is currently no method whereby material properties of thermal spray coatings may be predicted from fundamental processing inputs such as temperature-velocity correlations. The first step in such an important understanding would involve establishing a foundation that consolidates the thermal spray literature so that known relationships could be documented and any trends identified. This paper presents a method to classify and reorder thermal spray data so that relationships and correlations between competing processes and materials can be identified. Extensive data mining of published experimental work was performed to create thermal spray property-performance maps, known as ''TS maps'' in this work. Six TS maps will be presented. The maps are based on coating characteristics of major importance; i.e., porosity, microhardness, adhesion strength, and the elastic modulus of thermal spray coatings.

There has been considerable interest in the application of cold gas dynamic spray (CGDS) to deposit nickel-based superalloy coatings for the repair and development of high-value components that operate under extreme environmental conditions. The CGDS process introduces residual stresses in the coating layers, but inherently effects the subsurface of the substrate in a similar manner. The present study investigates the effect of low temperature range heat treatments (100-400°C) on the residual stress of CGDS Inconel Ò 718 deposited onto a presolution-treated Al7075-T651 substrate. High spatial resolution nondestructive residual stress measurements were carried out via neutron diffraction on both the CGDS deposit and substrate. The low temperature range heat treatments displayed a significant effect on both the substrate and coatings. Residual stress relaxation was exhibited in coatings that were heat-treated at the lowest temperature, whereas an increased heat treatment temperature displayed an opposite effect, increasing both the compressive residual stress in the IN718 coating and the residual tensile stress in the substrate. It is proposed the difference in thermal expansion coefficient of the two materials was the main factor responsible for the residual stresses. The effect of post-heat treatment on coating microhardness and porosity is also presented.Keywords cold gas dynamic spray Á heat treatment Á neutron diffraction Á nickel-based superalloy Á residual stress

In this study, we have examined ceramic matrix composites with silicon carbide fibers in a melt-infiltrated silicon carbide matrix (SiC/SiC). We subjected samples to tensile loads while collecting micro X-ray computed tomography images. The results showed the expected crack slowing mechanisms and lower resistance to crack propagation where the fibers ran parallel and perpendicular to the applied load respectively. Cracking was shown to initiate not only from the surface but also from silicon inclusions. Post heat-treated samples showed longer fiber pull-out than the pristine samples, which was incompatible with previously proposed mechanisms. Evidence for oxidation was identified and new mechanisms based on oxidation or an oxidation assisted boron nitride phase transformation was therefore proposed to explain the long pull-out. The role of oxidation emphasizes the necessity of applying oxidation resistant coatings on SiC/SiC.

The coverage of a deposited material that arises from the integration of discrete splat areas is an essential parameter that needs to be understood during thermal spray processes. However, there is absence of a theoretical method to predict and estimate the area coverage per pass by a thermal spray torch; for example by the plasma spray process. In this study, a model is presented that calculates the splat area coverage for a thermal spray process of ceramic materials. A focused survey of the published literature takes into consideration experimental observations that are related to this work. The model accounts for physical events in thermal spray processes, such as the use of a mono‐modal feedstock and size of spray stream. The model predictions for the area coverage of plasma sprayed yttria‐stabilized zirconia (YSZ) ranged between 12% and 18% depending on the value assumed for the maximum flattening ratio.  The results for the model were demonstrated via wipe studies where microscope glass slides were spray coated with YSZ and image analysis conducted. The average coverage calculated was approximately 13% for the sprayed images. The experiment verifies that the simulation results from the model predict adequately the splat area coverage of a thermal spray process.