Ablation mechanism and morphology evolution of the HfC-SiC coating for C/C composites deposited by supersonic atmospheric plasma spraying

Abstract

HfC-SiC protective coating was deposited on the surface of SiC-coated carbon/carbon composites by supersonic atmospheric plasma spraying due to the high arc temperature and the efficient deposition rate. The morphology and microstructure of the HfC-SiC coating were analyzed by X-ray diffraction and scanning electron microscopy. The results showed that Hf and Si elements distributed uniformly in the coating and the coating was dense without crack. Ablation resistance test was processed by oxyacetylene torch. During the ablation process, the sintering rate of HfO2 was slow, and more oxygen diffused into the internal coating, which caused the oxidation of the internal coating and damaged the structure of internal coating in the ablation center region. In addition, during cooling process, a new phase HfSiO4 was generated by the reaction between HfO2 and SiO2, which acted as a pinning agent to prevent the further expansion of the crack.

Single-source-precursor synthesis and air-plasma ablation behavior of (Ti,Zr,Hf)C/SiC ceramic nanocomposites at 2200 °C

“…Fig 13. Mass and linear ablation rates of A-T2Z3H5 in this work compared with that of other component ceramics and multi-component UHTC coatings form Ref [12,14,15,[46][47][48][49][50]…”

“…hinder the diffusion of oxygen atoms (so called pinning effect) [15,54]. The uniform distribution of (Ti,Zr,Hf)O2 particles in molten phases is attributed to the high content of (Zr+Hf) and the low content of preventing the agglomeration of (Ti,Zr,Hf)O2 due to the low diffusion coefficient of Zr and Hf [55].…”

Deposition of graded SiO2/SiC coatings using high-velocity solution plasma spray

“…3 shows the XRD patterns of the substrate and coatings obtained by the HVSPS process. In comparing the patterns, that from the substrate contains only a peak at the carbon-related diffraction angle (25°), while those from the coated samples show peaks of SiO 2 (22°) and SiC (35°) [29,30]. The formation of the SiC is evident from the pattern of sample SMP3.…”

Microstructure and Ablation Behavior of Low-Pressure Plasma Sprayed ZrB2 Coatings Down to 100 Pa

“…The porous feature of resultant composite coating requires sealing of in situ service at high temperature to prevent oxygen penetration into ZrB 2 coating. Moreover, for coatings deposited under ambient atmosphere, the spray particles are oxidized, because air could get involved into the plasma jet (Ref [15][16][17]19). The incorporation of oxides resulting from oxidation of spray particles during spraying reduces the content of ablationresistant pure ZrB 2 phase and thus deteriorates the overall ablation resistance.…”