Effect of Mild Oxidation on Ablation Properties of ZrSiO 4 Coating Prepared by Supersonic Atmospheric Plasma Spraying on
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Effect of Mild Oxidation on Ablation Properties of ZrSiO4 Coating Prepared by Supersonic Atmospheric Plasma Spraying on Carbon/Carbon Composites Can Sun1 • Cong-min Xu1 • Wei-feng Cao1
Submitted: 20 January 2020 / in revised form: 17 August 2020 Ó ASM International 2020
Abstract To eliminate the thermal expansion mismatch and improve the bonding strength between ZrSiO4 coating prepared by supersonic atmospheric plasma spraying and C/C composites, a layer with porous structure was produced on the substrate by a preliminary air oxidation treatment. The morphology and microstructure of the ZrSiO4 coating were characterized by SEM and XRD. The results showed the coating prepared under the condition of mild oxidation treatment exhibited good bonding strength and outstanding anti-ablation ability. After ablation for 120 s, the linear and mass ablation rates of the samples with mild oxidation were - 1.5 9 10-4 mm/s and 0.88 9 10-3 g/s, respectively, which were lower than those without oxidation treatment. The bonding strength of the samples with mild oxidation reached 7.9 MPa, which was 97.4% higher than those without mild oxidation. The excellent ablation resistance is attributed to the fact that oxidation treatment could make the surface rougher and enhance the bonding strength to decrease the thermal stress between the coating and substrate. Keywords ablation properties C/C composites mild oxidation supersonic atmospheric plasma spraying
& Can Sun [email protected] 1
School of Materials Science and Engineering, Xi’an Shiyou University, Xi’an 710065, China
Introduction Although carbon/carbon (C/C) composites are widely investigated as candidates for application in advanced space systems (Ref 1-4), poor ablation resistance under erosion by ultrahigh temperature and high-speed airflow becomes one of the key problems which limit C/C composites application (Ref 5-7). Therefore, enhancing ablation resistance is crucial for C/C composites, application in more areas. Applying ablation resistant coatings (ZrC-SiC (Ref 8), TaC (Ref 9) and SiC/HfC/SiC (Ref 10)) is the most common method to improve ablation resistance for C/C composites (Ref 11, 12). Ceramic coating systems, such as C/SiC, yttrium silicate, ZrO2-CaO-ZrSiO4, ZrO2-Y2O3ZrSiO4 and MoSi2-SiC-Si/SiC/borosilicate glass coating have been developed (Ref 13-15). It has been reported that the mixed protective layer of ZrO2 ? SiO2 possessed good oxygen resistance property and self-healing performance at high temperature (Ref 16), so ZrSiO4 which could decompose into ZrO2 and SiO2 at high temperature, is regarded as a promising anti-oxidation coating material for C/C composites. However, poor interfacial bond strength and large thermal stress between the C/C substrate and ZrSiO4 coating restrict the ability of the coating to protect the matrix. Mild oxidation treatment of C/C before depositing the coating is expected to be an effective approach to solve this problem. That is to say, the C/C composites are firstly put in a high-temperature and oxidi
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