In this paper ZrC coating was prepared on SiC coated graphite as a substrate by atmospheric plasma spray (APS) and solid shielding/ shrouded plasma spray (SSPS) methods. Microstructure observation and phase identification of the coatings were performed by scanning elect More
In this paper ZrC coating was prepared on SiC coated graphite as a substrate by atmospheric plasma spray (APS) and solid shielding/ shrouded plasma spray (SSPS) methods. Microstructure observation and phase identification of the coatings were performed by scanning electron microscopy and X-ray diffraction. The ablation behavior of the coating was evaluated under supersonic flame for 60s. The results showed that the ZrC coating enhance the ablation resistance of SiC coated graphite remarkably. The results of ablation test revealed that the linear and mass ablation rates of the ZrC coating applied by APS method were 3.7×10-3 mm.s-1 and 22×10-3 g.s-1, while those for SSPS coating were 2.2×10-3 mm.s-1 and 14×10-3 g.s-1, respectively. The excellent ablation resistance is attributed to the formation of continuous zirconia (ZrO2) layer on the surface during the oxidation of the ZrC coating. Moreover, the SPS-ZrC coated sample with lowest pores and cracks have better ablation resistance during the ablation test and can protected the graphite substrate against ablation sufficiently.
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In this research, a double layer thermal barrier coating was applied and then an alumina diffusion barrier layer was deposited on the YSZ by two solution precersore plasma and solution precersore flame spraying. High temperature oxidation and thermal shock resistance te More
In this research, a double layer thermal barrier coating was applied and then an alumina diffusion barrier layer was deposited on the YSZ by two solution precersore plasma and solution precersore flame spraying. High temperature oxidation and thermal shock resistance tests were done at 1100˚C. Microstructure of coatings were studied by optical Microscopy and Field Emission Scanning Electron Microscopy. Comparison of the microstructures of coatings showed that applying of Alumina with the solution precursor flame spray process upgrades the thermal properties. High temperature oxidation and thermal shock resistance of YSZ/Al2O3 coatings with Alumina applied by the solution precersoure thermal spray with the same compound were studied. Findings showed that applying alumina with the solution precursor flame spray process leads to increase the amount of the deposited splats and proper contact between them, causes to decrease the diffusion of O2 and as a result TGO thickness decreases and also thermal shock resistance increases.
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In this research, firstly amorphous Alumina powder was produced by co-precipitation method. Then YSZ/Al2O3 coatings were applied by plasma spraying process in two types of pyrolyzed and crystalline nano-alumina. High temperature oxidation and thermal shock resistance te More
In this research, firstly amorphous Alumina powder was produced by co-precipitation method. Then YSZ/Al2O3 coatings were applied by plasma spraying process in two types of pyrolyzed and crystalline nano-alumina. High temperature oxidation and thermal shock resistance test were done at 1100˚C. Microstructure and phase analysis of coatings were studied by optical and electron microscopes and XRD method. Comparison of the microstructure of coatings showed that the use of crystalline nano-alumina powder in the YSZ/Alumina layer composite upgrades the thermal properties. High temperature oxidation and thermal shock resistance of plasma sprayed YSZ/Al2O3 with un-pyrolysed nano-alumina and coatings with same composition with crystalline nano-alumina to created by plasma spraying were studied. Findings showed that the use of un-pyrolyzed nano-alumina powder in YSZ/Al2O3 layer composite resulted in increased porosity and shrinkage cavities in the coating, which increased the diffusion of O2 that causes the TGO growth rate. Also, high density and proper contact between the splats made of crystalline nano-alumina powder results in higher resistance of thermal cycles.
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