The use of C7H8 as the carbon source resulted in distinct surface morphologies and crosssections as shown in Figure and Figure , respectively. At a deposition temperature equal to or lower than 1250 ℃, the growth is columnar, and the sample surface is dominated with the crystals resembling the top of hexagonal pyramids. It can also be noticed that the crystal size first increases when temperature rises from 1100 ℃ to 1200 ℃ and slightly decreases at 1250 ℃. The 6-fold symmetric pyramids was assumed to be formed by a pair of twin triangular pyramids joining each other and is a typical morphology of coatings with <111>-oriented face-centered cubic (FCC) crystal structure , whereas the pyramids with 4-fold symmetry was reported to be FCC crystals with <110> orientation . The dense and dark striations seen in either the surface morphologies (Figure ) or the cross-sections (Figure ) of the samples prepared at T ≤ 1250 °C has previously been shown to be twins parallel to the (111) planes , implying that these samples are highly <111>-oriented. When the temperature is further increased above 1300 ℃, the surface turns into loose fibers and the coating becomes porous, suggesting a different deposition chemistry. faceted crystals which increase in size with increasing deposition temperature are formed. A growth mode transition from fine crystallite to columnar with increasing temperature can be observed in the cross-sectional images shown in Figure . In contrast to the C7H8 process where a shift of growth orientation from <111> to <110> is seen with higher temperatures, the diffractograms for the 3C-SiC coatings prepared in the CH4 process show a change from randomly oriented to <110>-oriented growth between 1200 °C and 1300 °C.