h-BN layers were deposited on α-SiC substrates by CVD at high temperature (1500-1900°C) using B2H6 and NH3 diluted in Ar. Growth rates were in the 6-10 µm/h range. In all the conditions studied, the BN as deposited layers were found to be translucent to light, some having a light whitish aspect and other a more yellowish one. It was also observed that the deposit was not always adhesive. µ-Raman and TEM characterization showed that the layers were nano-crystalline with crystallite size < 10 nm. The growth rate was found temperature and N/B ratio dependent due to an N limited growth regime which is more pronounced above 1700°C.