Material of Sm2Zr2O7composition powder was synthesized by coprecipitation method using Sm2O3and ZrOCl2•8H2O as raw materials, and applied as ceramic topcoats of thermal barrier coating (TBC) by atmospheric plasma spraying (APS). The ceramics powder was prepared with proper distribution of particle size about 30-70μm by spray-dried method. Phase analyses revealed that Sm2Zr2O7coatings keeping the single phase with pyrochlore structure before and after the thermal cycling test. The thermally grown oxide at the topcoat-bondcoat interface and the formation of transverse crack were the major factors that lead to the coating failure on thermal cycling.
The zirconium silicate can be deposited as functional coatings which will be used at high temperature because of its high melting point and low thermal conductivity. It can also prevent the oxygen of the environment through the coatings and react with the substrate. In this paper, plasma spraying technology was selected to prepare the coatings of zirconium silicate. The orthogonal design method was used to optimize the parameter of plasma spraying process. The content of zirconium silicate in the coatings was checked by XRD because of the decomposition of the zirconium silicate at 1711K.The bond strength and porosity of the coatings were also measured after the optimizing of the plasma spraying parameters in this paper. According the impact on the porosity, the factors of the process can be ordered as follows: spraying distance, current, primary gases and secondary gases. And the order of spraying factors according the impact on the content of zirconium silicate in the coatings was showed as follows: spraying distance, secondary gas, primary gas and current.
Carbon fiber reinforced carbon matrix composites (C/C) have received much attention due to their excellent high-temperature strength, high thermal conductivity, low coefficient of thermal expansion (CTE), good thermal shock resistance. However, the poor ablation resistance of the C/C restricts its high temperature ablating applications. Making a thin anti-ablation coating on the C/C has been proved to improve the performance effectively. In order to improve the anti-ablation property of the composite, MoSi2 coatings were deposited by Atmosphere Plasma Spraying (APS) on the SiC covered C/C matrix. The SiC coatings were prepared by pack cementation. Oxyacetylene flame torch was selected to simulate the ablation situation. The ablation temperature was 1800°C. XRD and SEM were employed to discover the diversification of the coatings structure and composition. And the mechanism of anti-ablation of the MoSi2 coatings system was investigated in this paper.
To develop novel and advanced thermal barrier coatings, full-scale numerical simulation of plasma-sprayed functionally gradient materials is conducted in this paper, including the prediction of basic parameters at the nozzle exit, simulation of three dimensional simulation of the plasma jet, modeling of the interaction between the plasma jet and the particles, calculation of flight trajectories and temperature history of flying metal and ceramic particles, the interaction between the molten particles and the substrate, as well as the deposition process of the coatings. Various complex phenomena, such as turbulent effects with chemical reactions in the plasma jet, dispersion status of the particles onto the substrate, and the composition distribution of the functionally gradient materials, are fully taken into account. The numerical simulation results are found to be in good agreement with experimental evidence.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.