Preparation of a nanostructured SiC-ZrO2 coating to improve the oxidation resistance of graphite

High temperature anti‐oxidation behavior of in situ and ex situ nanostructured C/SiC/ZrB2‐SiC gradient coatings: Thermodynamical evolution, microstructural characterization, and residual stress analysis

“…It might have penetrated into the coating pores by the gravity‐induced flow and transferred below the powders pack, or it might have been vaporized due to the high vapor pressure above 1473K (1200°C). Moreover, some B 2 O 3 can react with SiO 2 or dissolve into it, promoting the formation of a borosilicate glass with a higher melting point and lower vapor pressure and viscosity than those of the silica scale …”

“…Moreover, some B 2 O 3 can react with SiO 2 or dissolve into it, promoting the formation of a borosilicate glass with a higher melting point and lower vapor pressure and viscosity than those of the silica scale. 9,31 Cross-section SEM image of Ex-SZ sample and the element mapping of surface layer after 1 hour of oxidation in Figure 12B represent the oxidation of carbon substrate in some regions, occurring due to the lack of continuous protective silica layer on the surface and penetration of oxygen into the substrate. After 1 hour, due to the increase of SiO 2 phase fraction, both In-SZ and Ex-SZ samples show weight gain.…”

“…There are two methods for improving the oxidation resistance of carbon‐based materials: (i) introducing the oxidation inhibitors (such as Al, B, and Si) into the carbon matrix, which can decrease the oxidation rate of carbon materials; (ii) applying the single‐layer or multilayer ceramic coatings. Over the last years, different types of single‐layer and multi‐layer coatings have been developed such as SiC/HfC, SiC/TaB 2 –SiC–Si, TaB 2 –TaSi 2 –SiC‐Si/TaC‐SiC, ZrC–SiC, SiC/ZrB 2 –SiC, SiC/MoSi 2 –SiC–B, MoSi 2 ‐SiC, SiC–ZrO 2, etc.…”

Ti–Zr coating on graphite through powder immersion reaction-assisted coating (PIRAC) and its oxidation kinetics at $$T =1000{^{\circ }}\hbox {C}$$ T = 1000 ∘ C

“…Graphite has always been known as a heat-resistant, lightweight and highly thermal-conductive material. Hightemperature application frequently involves graphite, especially in the core of nuclear reactors, such as neutron moderators and reflectors which slows down fast neutrons [1,2] and is used in high-temperature structural application, such as turbine components [3]. The main disadvantage of graphite is its low hardness (27-61 HV); furthermore, the nuclear grade graphite IG-110 is susceptible to oxidation at moderate temperature (600 • C) [4].…”

“…Many researchers take a conceded effort to enhance the weak characteristics of graphite through coating. Several methods have been explored, a few of these are as follows: pyrolytic carbon coating [1], pack cement process SiC−ZrO 2 coating [3], rf bias sputtering [5], chemical vapour deposition [6,7], vacuum plasma spraying process [8] and powder immersion reaction-assisted coating (PIRAC) [9,10]. The PIRAC process has been known as a diffusional process due to the strong adhesion between the coated materials and substrate; otherwise, complex shapes can be coated by this process.…”