Effect of calcium carbonate addition on carbothermic formation of hexagonal boron nitride

Topkaya, Yavuz Ali
Effect of CaCO3 on formation of hexagonal boron nitride (h-BN) was investigated by holding CaCO3 free and CaCO3 added activated carbon-boric oxide mixtures under nitrogen atmosphere at 1500 degrees C for 30-120 min. Amount of CaCO3 addition was varied in the range of 0-50 wt.% of the initial mixture. Products were characterized by powder X-ray diffractometry, FT-IR analysis, quantitative chemical analysis, scanning electron microscopy and BET specific surface area analysis. It was observed that calcium carbonate addition led to an increase in the amount and the grain size of hexagonal boron nitride and a decrease in the amount of boron carbide forming. Ten weight percent calcium carbonate addition was found to be the optimum value for increasing the yield of hexagonal boron nitride and decreasing the formation of boron carbide.


Effect of calcium oxide addition on carbothermic formation of hexagonal boron nitride
Özkenter, Ali Arda; Sevinç, Naci; Department of Metallurgical and Materials Engineering (2009)
Hexagonal boron nitride (h-BN) formation by carbothermic reduction of B2O3 under nitrogen atmosphere at 1500°C and effect of CaO addition into the initial B2O3 – active C mixture were investigated during this study. Reaction products were characterized by powder X-ray diffraction, scanning electron microscopy (SEM) and quantitative chemical analysis. Main aim of this study was to investigate the presence of a second reaction mechanism that catalytically affects h-BN formation during CaO or CaCO3 addition in...
Highly Efficient Room Temperature Synthesis of Silver-Doped Zinc Oxide (ZnO:Ag) Nanoparticles: Structural, Optical, and Photocatalytic Properties
Yildirim, Ozlem Altintas; Ünalan, Hüsnü Emrah; Durucan, Caner (Wiley, 2013-03-01)
Synthesis of silver-doped zinc oxide (ZnO:Ag) nanoparticles through precipitation method has been reported. The synthesis was conducted at room temperature and no subsequent thermal treatment was applied. ZnO nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), fourier transmission infrared spectroscopy (FTIR), and ultraviolet-visible (UVVis) spectroscopy. Detailed crystallographic investigation was accomplished through ...
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...
TIMUCIN, M; MUAN, A (Wiley, 1992-06-01)
Activities of NiO were measured in the oxide and spinel solutions of the system MnO-NiO-Al2O3 at 1300-degrees and 1400-degrees-C with the aim of deriving information on the thermodynamic properties of the spinel phases. Synthetic samples in selected phase assemblages of the system were equilibrated with metallic nickel and a gas phase of known oxygen partial pressures at a total pressure of 1 atm. The data on NiO activities and directions of conjugation lines between coexisting oxide and spinel phases were ...
Improvement in sinterability and phase stability of hydroxyapatite and partially stabilized zirconia composites
Evis, Zafer; KUTBAY, IŞIL (Elsevier BV, 2009-03-01)
Composites of hydroxyapatite with partially stabilized zirconia with MgO or MgF2 were pressureless sintered between 1000 degrees C and 1300 degrees C. The reactions and transformations of phases were verified by X-ray diffraction. For the hydroxyapatite and zirconia composites with MgO, calcium from the hydroxyapatite diffused into the zirconia phase, and the hydroxyapatite decomposed to tri-calcium phosphate at sintering temperatures higher than 1000 degrees C. Above about 1200 degrees C, CaZrO3 was formed...
Citation Formats
H. E. ÇAMURLU, N. SEVİNÇ, and Y. A. Topkaya, “Effect of calcium carbonate addition on carbothermic formation of hexagonal boron nitride,” JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, pp. 679–689, 2008, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/40043.