Chemical vapour growth of CrB 2 and CrB crystals

Abstract

Crystals of CrB 2 and CrB were grown from a gaseous mixture of CrCl 2, BCl 3, H 2 and Ar in a temperature range of 1050–1100°C. Hexagonal planar crystals of CrB 2 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 CrB 2 was confirmed by gravimetric analysis to be nearly stoichiometric. The microhardness of CrB 2 and CrB deposits was measured to be as 3800–4000 and 1450–1500 kg/mm 2, respectively.