A non-destructive inspection technique known as photoluminescence piezospectroscopy (PLPS) has been used to measure residual stresses in thermally grown oxide layers in TBCs subjected to thermal cycling at 1121 °C. YSZ topcoats were applied by atmospheric plasma spraying on cold-sprayed bond-coated Ni superalloy substrates. Residual stresses were analyzed as a function of thermal exposure. Changes in stress were used to indicate spallation and damage degree in the coating system.

In this study, Vickers indentation testing is used to determine the fracture toughness of hard flame spray coatings produced from cored-wire feedstocks, including WC-10Co4Cr, 75CrCo-25NiCr, and WC-12Co. Average measured values are compared with fracture toughness values calculated from seven different equations found in the literature in order to validate the experimental results and to better understand the relationship between fracture toughness and coating hardness for each of the tested materials.

This work evaluates and compares the properties of weld overlays and thermal spray coatings produced using different feedstock materials. The mechanical and metallurgical characteristics of the coatings and their performance in corrosion and wear tests are discussed.

Thermal spraying covers a range of spraying processes in which any metallic, ceramic or polymer-based material can be sprayed onto a substrate to be protected. This flexibility of thermal spraying makes the technology extremely successful in different engineering applications. Protection of the metallic components by hard oxide or ceramic-metallic coatings has proven to be an effective way to reduce wear and corrosion. Polymer coatings are increasing in importance as protection against corrosion and wear for several environmental conditions. Polymeric materials typically exhibit a low shear strength and low elastic modulus that make them viable for use under tribological conditions. Thermally sprayed polymers have the potential both to lower material costs and improve coating performance in drastic environments. In this work, a comparative study is carried out to evaluate the performance of some thermoplastic and hydrocarbon derived polymers deposited onto steel by thermal spray technology. Several tests were performed to evaluate the obtained coatings mainly related to tribological performance.

Thermal barrier coatings (TBCs) allow increasing combustion temperatures of gas turbines and diesel engines thus improving the system performance. Residual stresses due to the differences of thermal expansion coefficient between metallic bond coat and ceramic top coat as well as the stresses due to the oxidation of the bond coat and the consequent increase in the thermally grown oxide (TGO) layer lead to ceramic debonding and subsequent failure of the thermal barrier system in service conditions. Extensive research has been carried out to minimize such events by applying multilayered coatings, intermediate diffusion or protective layers and other methods. In this work the TBC systems were obtained by applying distinct bond coats and top coats. The bond coats were applied by High Velocity Oxygen Fuel (HVOF) and the ceramic top coats were applied by Air Plasma Spraying (APS). Residual stresses were measured by the Modified Layer Removal Method (MLRM). Isothermal high temperature oxidation tests were performed and the results were correlated with the post spraying stress state and the coating thermal history. Results show that the residual stresses are mainly influenced by the thermal history regarding the quenching of individual splats and the plastic deformation of ceramic deposits.