Materials and processing factors influencing stress evolution and mechanical properties of plasma sprayed coatings

0505278 - ÚFP 2020 RIV CH eng J - Journal Article
Matějíček, Jiří - Mušálek, Radek - Veverka, Jakub
Materials and processing factors influencing stress evolution and mechanical properties of plasma sprayed coatings.
Surface and Coatings Technology. Roč. 371, 15 August 2019 (2019), s. 3-13. ISSN 0257-8972
R&D Projects: GA ČR GB14-36566G; GA ČR(CZ) GA17-23154S
Institutional support: RVO:61389021
Keywords : Alumina * Copper * Four-point bending * Functionally graded materials * In-situ curvature method * Mechanical properties * Plasma spraying * Process-structure-property relationship * Residual stress * Water stabilized plasma
OECD category: Composites (including laminates, reinforced plastics, cermets, combined natural and synthetic fibre fabrics
Impact factor: 3.784, year: 2019
Method of publishing: Limited access
https://www.sciencedirect.com/science/article/abs/pii/S0257897219301227?via%3Dihub

Residual stress is an important factor that may influence the integrity of plasma sprayed coatings, as well as the performance and lifetime of coated parts. The stress, in turn, is influenced by the properties of the substrate and coating materials and by the processing conditions. Moreover, specific stress-strain behavior of plasma sprayed coatings stems from their characteristic structure, which is again influenced by the spraying parameters. In this work, the curvature and temperature monitoring by “ICP” (In-situ Coating Properties) sensor was used to track the stress evolution during and after coating deposition and to determine the coating stiffness - this was complemented by 4-point bending, hardness measurement, microstructural observations and image analysis. Representative ceramic, metallic and composite coatings, including functionally graded materials (FGMs), were investigated. The effects of processing parameters, such as deposition temperature, particle temperature and velocity, deposition rate and coating/substrate material combination were demonstrated. Ceramic Al 2 O 3 coatings exhibited residual stress values in tens of MPa and extensive splat cracking - their moduli were higher when loaded in compression than in tension. Metallic coatings (Cu, W, and W + Cu composites) showed residual stress values in hundreds of MPa without significant cracking. Residual stresses as well as coating moduli were higher for mixed W + Cu composites than for 100% W or 100% Cu coatings, possibly as a result of stronger intersplat bonding across heterogeneous interfaces. It was also shown that residual stress profiles in W + Cu FGMs may be significantly altered by intentional design of the gradation profile and that experimental data evaluated by ICP during the actual deposition of the FGM coating were in good agreement with theoretical model based on data from the deposition of individual mixed W + Cu layers. Higher stress and modulus magnitudes were generally observed under conditions resulting in stronger bonding between the splats.
Permanent Link: http://hdl.handle.net/11104/0296749