High temperature oxidation behavior of graphite coated by dual layer of nano-SiC/SiC

In this research, a dual-layer coating was used to improve high temperature oxidation resistance of graphite substrate. For first layer, silicon carbide was applied by pack cementation method. Powder pack consisted of Si, SiC and Al2O3 and heat-treated at 1650°C in an argon atmosphere. SEM and XRD characterizations confirmed formation of SiC diffusion coating with about 500 μm including compositionally gradient of C and Si elements. Electrophoretic deposition (EPD) was used to deposit nano SiC (SiCn) as second layer. Thickness of second layer of SiCn in corresponded optimal situation was 50μm. Samples with single and dual layers were investigated in oxidation test at 1400°C. Results showed that an extreme increase was occurred in oxidation resistance after application of second layer of nano SiC. Weight loss value for single layer coating of SiC and dual layer coating of SiCn/SiC after oxidation test for 28h at 1400°C were 20 wt.% and 1 wt.%, respectively

کلیدواژه ها:

Oxidation ، Coating ، Nano SiC ، Pack Cementation ، Electrophoretic Deposition