Chemical vapour growth of CrB2 and CrB crystals

Crystals of CrB2 and CrB were grown from a gaseous mixture of CrCl2, BCl3, H2 and Ar in a temperature range of 1050–1100°C. Hexagonal planar crystals of CrB2 grew to a size of 6 mm in diagonal and 0.1 mm in thickness at 1050°C for 2 h. Hollowed pillar crystals of CrB (1–10 μm thick and 30–100 μm long) grew on a platinum dispersed substrate at 1100°C. The growth mechanism of quasi-nonagonal pillars of CrB was supposed to be repeated twinning across the (110) planes. The composition of CrB2 was confirmed by gravimetric analysis to be nearly stoichiometric. The microhardness of CrB2 and CrB deposits was measured to be as 3800–4000 and 1450–1500 kg/mm2, respectively.