Preparation of borides in Nb–B and Cr–B systems by combustion synthesis involving borothermic reduction of Nb2O5 and Cr2O3

In situ synthesis of NbB2–NbC composite powders by milling-assisted carbothermal reduction of oxide raw materials

“…Many processes are available for the fabrication of niobium boride or niobium boride-based ceramic powders including high temperature methods using solid state reactions, borothermal and carbothermal reductions [14][15][16][17][18][19][20][21], low-temperature synthesis in an autoclave [22,23], self-propagating high-temperature synthesis (SHS) [3,[24][25][26][27], chemical vapour deposition (CVD) [8] and ball milling and mechanochemical synthesis [28,29]. Borothermal and carbothermal reductions require temperatures above 1600°C to obtain the niobium boride phase if Nb 2 O 5 and B/B 2 O 3 are used as starting materials [14,15,21].…”

“…NbB 2 nanocrystals were obtained from chloride-based raw materials at low temperatures (500-600°C) using an autoclave [22,23]. SHS processes were conducted using Nb/B and Nb 2 O 5 /B powder mixtures, and non-stoichiometric phases of niobium boride were obtained instead of a single NbB 2 phase [24][25][26][27]. NbB 2 was prepared by chemical vapour deposition using gas mixtures of NbCl 5 , BCl 3 and H 2 on a quartz substrate between the temperatures of 950 and 1200°C, resulting in the production of homogeneous films between 950 and 1050°C and pillar crystals between 1050 and 1200°C during the precipitation step of the process [8].…”

Solid and Liquid Synthetic Routes of Vanadium, Niobium and Titanium Nano-metal Borides

“…Solution was filtered and washed with distilled water and ethanol. The precipitate was then treated with 1 N NH 4 Cl at 100°C for three hours under magnetic stirring. Solution was filtered and washed with distilled water and ethanol and dried in a vacuum oven at 150°C for 3 hours.…”

“…Due to special characters including high hardness, high melting points, high-temperature strength, corrosion resistance, chemical stability, wear resistance and electrical properties [1][2][3][4][5][6], a great number of transition metal borides were synthesized. Metal borides like VB 2 , CrB 2 , TiB 2 , W 2 B 5 and others have been used as a coating to strengthen carbon steels to resist electronic heating with high power density in vacuum, in one case layers of vanadium boride VB 2 are coated on steel surface [7].…”

Nano-Metal Borides of Cobalt, Nickel and Copper

“…Due to special characters of transition metal borides including high hardness, high melting points, high-temperature strength, corrosion resistance, chemical stability, wear resistance and electrical properties, transition metal borides have a wide applications in different fields like medicine, high resistant furnaces and others [9][10][11][12][13][14].…”