Oxidation behavior and kinetics of SiC/alumina–borosilicate coating for carbon–carbon composites

A mullite/SiC oxidation protective coating for carbon/carbon composites

“…The oxidation activation energy of the mullite/SiC coated C/C composites is calculated to be 111.11 kJ/mol. According to Li's and Wu's research, 19 the oxidation activation energy is 112 kJ/mol, only when the oxidation process of the coated C/C is controlled by the diffusion rate of oxygen along the dense SiO 2 glass film. Therefore, it can be concluded that oxidation process of the mullite/SiC coated C/C composites is main controlled by the diffusion rate of the oxygen through the dense SiO 2 and silicates glass that generated from the mullite outer layer at the temperature range of 1573-1773 K. This also infers that the multi-layer coatings have the best oxidation resistance at 1573-1773 K.…”

“…[13][14][15][16] In addition, the good match of thermal expansion coefficient and good physical and chemical compatibility between mullite (4.4-5.6 × 10 −6 / • C) and SiC (4.3-5.4 × 10 −6 / • C) are another advantage for the adoption of mullite as outer coating material. 17 However, the traditional technologies, such as chemical vapor deposition, 14,18 slurry dipping 19,20 and pack cementation 1,3 are either high-cost or time-consuming. Hydrothermal electrophoretic deposition has been demonstrated to be a facile method to prepare dense coatings with high efficiency and simple operation.…”

Effect of processing parameters on microstructure and ablation behavior of SiC/ZrB2 coating for graphite

“…Among these developed coatings, SiC coating shows a great potential for protection of graphite from oxidation at high temperature due to the beneficial formation of a protective SiO 2 surface film that can efficiently prevent from diffusion of oxygen into the substrate . Unfortunately, due to thermal expansion mismatches between carbon substrate and the SiC ( α SiC = 3 × 10 −6 ‐5 × 10 −6 /C, α C = 2.2 × 10 −6 ‐3 × 10 −6 /C), poor adhesion is generally obtained along with a high crack density in the coating . One of the approaches employed to solve this problem is the formation of the SiC coating with transition interface.…”

“…The molten Si fills the pores and reacts with the carbon and finally forms the SiC coating. [5][6][7] The holding time and infiltration temperature are main parameters during RMI process which affect the microstructure and oxidation resistance of the SiC coating. 9 Feng et al 10 produced the SiC coating on the C/C composites substrate by pack cementation rout and studied the effect of infiltration temperature on oxidation resistance and microstructure of as prepared coating.…”

“…During the RMI process, melted Si penetrates into the carbon substrate through porosities using capillary force. The molten Si fills the pores and reacts with the carbon and finally forms the SiC coating . The holding time and infiltration temperature are main parameters during RMI process which affect the microstructure and oxidation resistance of the SiC coating .…”