Carbothermic production of hexagonal boron nitride

Çamurlu, Hasan Erdem
Formation of hexagonal boron nitride (h-BN) by carbothermic reduction of B2O3 under nitrogen atmosphere at 1500oC was investigated. Reaction products were subjected to powder X-ray diffraction analysis, chemical analysis and were examined by SEM. B4C was found to exist in the reaction products of the experiments in which h-BN formation was not complete. One of the aims of this study was to investigate the role of B4C in the carbothermic production of h-BN. For this purpose, conversion reaction of B4C into h-BN was studied. B4C used in these experiments was produced in the same conditions that h-BN was formed, but under argon atmosphere. It was found that formation of h-BN from B4CB2O3 mixtures was slower than activated CB2O3 mixtures. It was concluded that B4C is not a necessary intermediate product in the carbothermic production of h-BN. Some additives are known to catalytically affect the h-BN formation. The second aim of this study was to examine the catalytic effect of some alkaline earth metal oxides and carbonates, some transition metal oxides and cupric nitrate. It was found that addition of 10wt% CaCO3 into the B2O3+C mixture was optimum for increasing the rate and yield of h-BN formation and decreasing the B4C amount in the products and that the reaction was complete in 2 hours. CaCO3 was observed to be effective in increasing the rate and grain size of the formed h-BN. Addition of cupric nitrate together with CaCO3 provided a further increase in the size of the h-BN grains.


Production of boron nitride by carbothermic and mechanochemical methods, and nanotube formation
Camurlu, HE; Aydogdu, A; Topkaya, Yavuz Ali; Sevinc, N (2003-09-12)
The formation of hexagonal boron nitride by carbothermic reduction of boron oxide and nitridation has been examined. Experiments were conducted in the temperature range of 1100-1500degreesC for durations between 15-240 minutes. Products were examined by X-ray, SEM and chemical analysis. The results showed that the reaction proceeds through a gaseous boron containing species, which is most probably 13203(g). It was found that all of the carbon was consumed and formation of boron nitride was complete in 2 hou...
Carbothermic formation of boron nitride
Aydogdu, A; Sevinc, N (Elsevier BV, 2003-01-01)
Formation of boron nitride by reaction of boric oxide with carbon and nitrogen was studied. It was found from the results of experiments conducted by holding BA-activated C mixtures under a flowing nitrogen atmosphere that formation of boron nitride was complete in 120 min at 1500 degreesC. After cleaning the reaction product from the ash of the activated carbon and from the unreacted B2O3 pure BN powder was obtained. B4C was found to exist as an intermediate species in the reaction products of the experime...
CVD of boron and dichloroborane formation in a hot-wire fiber growth reactor
Sezgi, Naime Aslı; Dogu, T; Ozbelge, HO (2001-11-01)
Chemical vapor deposition (CVD) of boron by hydrogen reduction of BCl, on a hot tungsten substrate was investigated in a parallel flow reactor. Effect of substrate temperature (1100-1250 degreesC) on the relative rates of formation of BHCl2 and boron was observed by the on-line analysis of the reactor effluent stream composition using an FT-IR spectrophotometer. It was concluded that BHCl2 was majorly formed in the gas phase within the thermal boundary layer adjacent to the substrate with possible contribut...
Gas phase reaction kinetics in boron fibre production
Firat, Fatih; Sezgi, Naime Aslı; Ozbelge, Hilmi O.; Doğu, Timur (2012-05-01)
In the production of boron fibres using the chemical vapor deposition (CVD) technique, boron deposition and dichloroborane formation reactions occurs simultaneously. Boron deposition reaction occurs at the surface, whereas the formation of dichloroborane is the result of both gas phase and surface reactions. A continuous stirred tank reactor (CSTR) type of reactor was designed to investigate the reaction kinetics and kinetic parameters in the gas phase reactions of boron trichloride and hydrogen. It was con...
Flame retardancy effects of zinc borate and nanoclay in ABS, and boron compounds in PET
Özkaraca, Ayşe Çağıl; Kaynak, Cevdet; Department of Metallurgical and Materials Engineering (2011)
In this thesis there were two main purposes, the first one being to investigate effects of zinc borate (ZB) on the flammability behavior of ABS when used with and without a traditional brominated flame retardant (BFR) / antimony trioxide (AO) system. The second purpose was to investigate contribution of nanoclays (NC) to the flame retardancy performance of the same traditional BFR compound with various combinations of AO and ZB again in ABS matrix. For these purposes, materials were melt compounded by using...
Citation Formats
H. E. Çamurlu, “Carbothermic production of hexagonal boron nitride,” Ph.D. - Doctoral Program, Middle East Technical University, 2006.