CVD of boron and dichloroborane formation in a hot-wire fiber growth reactor

Sezgi, Naime Aslı
Dogu, T
Ozbelge, HO
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 contribution of surface reactions at higher temperatures. Comparison of results obtained in the impinging jet and parallel flow reactors indicated the significance of diffusion resistance in the parallel flow system. Tubular flow reactor experiments indicated that BHCl2 formation reaction started at temperatures as low as 350 degreesC and reached equilibrium in less than a second at temperatures over 420 degreesC.


Mechanism Studies on CVD of Boron Carbide from a Gas Mixture of BCl3, CH4, and H-2 in a Dual Impinging-jet Reactor
Karaman, Mustafa; Sezgi, Naime Aslı; Doğu, Timur; Ozbelge, Hilmi Onder (2009-03-01)
Nearly pure boron carbide free from impurities was produced on a tungsten substrate in a dual impinging-jet chemical vapor deposition reactor from a BCl3, CH4, and H-2 mixture. The Fourier Tran form Infrared (FTIR) analysis proved the formation Of reaction intermediate BHCl2, which is proposed to occur mainly in the gaseous boundary layer next to the substrate surface. Among a large number of reaction mechanisms proposed only the ones considering the molecular adsorption of boron carbide on the substrate su...
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...
Kinetic investigation of chemical vapor deposition of B4C on tungsten substrate
Karaman, Mustafa; Sezgi, Naime Aslı; Doğu, Timur; Ozbelge, H. Onder (2006-12-01)
Production of beta-rhombohedral boron carbide (B4C) on a tungsten substrate by the chemical vapor deposition from a BCl3-H-2-CH4 gas mixture was achieved. An impinging-jet reactor was used to minimize the mass-transfer limitations on the reaction kinetics, which made a detailed kinetic investigation possible. Results of the XRD and XPS analyses showed that the solid product formed on the substrate is a rhombohedral B4C phase. Both dichloroborane and boron carbide formation rates were found to increase with ...
BHCl2 formation during chemical vapor deposition of boron in a dual-impinging jet reactor
Sezgi, Naime Aslı; Ozbelge, HO (1997-12-01)
Chemical vapor deposition (CVD) of boron from BCl3 and Hz was investigated in a dual-impinging jet reactor which was connected to an FT-IR spectrometer for on-line chemical analysis of the reactor outlet stream. Formation of the intermediate, BHCl2, during CVD of boron on a hot tungsten substrate was experimentally verified, Boron deposition started at substrate temperatures of around 750 degrees C and showed a significant deposition rate increase with an increase in temperature. At a surface temperature of...
Thermal characterization of composites of polyamide-6 and polypropylene involving boron compounds via direct pyrolysis mass spectrometry
İşbaşar Afacan, Güllü Ceyda; Hacaloğlu, Jale; Yılmazer, Ülkü; Department of Polymer Science and Technology (2013)
In this work, the effects of addition of boron compounds, boron phosphate (BPO4), zinc borate (ZnB), borosilicate (BSi) and lanthanum borate (LaB), on thermal degradation characteristics of composites of polyamide 6 (PA6) and polypropylene (PP) are analyzed via Direct Pyrolysis Mass Spectrometry (DP-MS) technique. The composites of PA6 involve nitrogen containing flame retardants, melamine (Me) or melamine cyanurate (MC); or phosphorus containing flame retardant, aluminum diethylphosphinate (AlPi), with or ...
Citation Formats
N. A. Sezgi, T. Dogu, and H. Ozbelge, “CVD of boron and dichloroborane formation in a hot-wire fiber growth reactor,” CHEMICAL ENGINEERING AND PROCESSING, pp. 525–530, 2001, Accessed: 00, 2020. [Online]. Available: