Influence of TiC/C transition layers on coated graphite as thermal stress relieving layers

To relieve the thermal stresses at interface of TiC and graphite, compositionally graded TiC/C transition layers were prepared by chemical vapor deposition. Scanning electron microscopy (SEM), energy dispersion spectrometer (EDS) and X-ray diffraction (XRD) results indicated that the coatings were characterized by a gradient in morphologies and compositions. For further study, the effect of graded TiC/C coatings on the thermo-mechanical properties was evaluated. Results showed that the thermal conductivity of coated graphite decreased, and mechanical strength was increased. For practical use, thermal recycles between 298 K and 1273 K were carried out. Results indicated that the thermal shock resistance of TiC coatings was significantly improved by the transitions. To clarify the mechanism, finite element calculations were carried out and results suggest that thermal stress shifts at interface of graphite and TiC coatings were effectively relieved by the transition layers.