scholarly journals Structure of Diamond Films Grown Using High-Speed Flow of a Thermally Activated CH4-H2 Gas Mixture

Materials ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 219 ◽  
Author(s):  
Yu.V. Fedoseeva ◽  
D.V. Gorodetskiy ◽  
K.I. Baskakova ◽  
I.P. Asanov ◽  
L.G. Bulusheva ◽  
...  
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Carbon Coating ◽  
Diamond Films ◽  
Heating Power ◽  
Hydrogen Flow Rate ◽  
X Ray ◽  
Hydrogen Flow ◽  
Thermally Activated ◽  
Diamond Crystals

Diamond films are advanced engineering materials for various industrial applications requiring a coating material with extremely high thermal conductivity and low electrical conductivity. An approach for the synthesis of diamond films via high-speed jet deposition of thermally activated gas has been applied. In this method, spatially separated high-speed flows of methane and hydrogen were thermally activated, and methyl and hydrogen radicals were deposited on heated molybdenum substrates. The morphology and structure of three diamond films were studied, which were synthesized at a heating power of 900, 1700, or 1800 W, methane flow rate of 10 or 30 sccm, hydrogen flow rate of 1500 or 3500 sccm, and duration of the synthesis from 1.5 to 3 h.The morphology and electronic state of the carbon on the surface and in the bulk of the obtained films were analyzed by scanning electron microscopy, Raman scattering, X-ray photoelectron, and near-edge X-ray absorption fine structure spectroscopies. The diamond micro-crystals with a thick oxidized amorphous sp2-carbon coating were grown at a heating power of 900 W and a hydrogen flow rate of 1500 sccm. The quality of the crystals was improved, and the growth rate of the diamond film was increased seven times when the heating power was 1700–1800 W and the methane and hydrogen flow rates were 30 and 3500 sccm, respectively. Defective octahedral diamond crystals of 30 μm in size with a thin sp2-carbon surface layer were synthesized on a Mo substrate heated at 1273 K for 1.5 h. When the synthesis duration was doubled, and the substrate temperature was decreased to 1073 K, the denser film with rhombic-dodecahedron diamond crystals was grown. In this case, the thinnest hydrogenated sp2-carbon coating was detected on the surface of the diamond crystals.

Amorphous-to-nanocrystalline transition in silicon thin films by hydrogen diluted silane using PE-CVD method

2020 ◽  
Vol 13 ◽  
Author(s):  
Ashok Jadhavar ◽  
Vidya Doiphode ◽  
Ajinkya Bhorde ◽  
Yogesh Hase ◽  
Pratibha Shinde ◽  
...  
Keyword(s):  
Flow Rate ◽  
Volume Fraction ◽  
Defect Density ◽  
Hydrogen Flow Rate ◽  
Spectroscopy Analysis ◽  
Deposition Parameter ◽  
Hydrogen Flow ◽  
Cvd Method ◽  
Silicon Thin Films ◽  
Increasing Trend

: Herein, we report effect of variation of hydrogen flow rate on properties of Si:H films synthesized using PE-CVD method. Raman spectroscopy analysis show increase in crystalline volume fraction and crystallite size implying that hydrogen flow in PECVD promote the growth of crystallinity in nc-Si:H films with an expense of reduction in deposition rate. FTIR spectroscopy analysis indicates that hydrogen content in the film increases with increase in hydrogen flow rate and hydrogen is predominantly incorporated in Si-H2 and (Si-H2)n bonding configuration. The optical band gap determined using E04 method and Tauc method (ETauc) show increasing trend with increase in hydrogen flow rate and E04 is found higher than ETauc over the entire range of hydrogen flow rate studied. We also found that the defect density and Urbach energy also increases with increase in hydrogen flow rate. Photosensitivity (Photo /Dark) decreases from  103 to  1 when hydrogen flow rate increased from 30 sccm to 100 sccm and can attributed to amorphous-to-nanocrystallization transition in Si:H films. The results obtained from the present study demonstrated that hydrogen flow rate is an important deposition parameter in PE-CVD to synthesize nc-Si:H films.

scholarly journals Sliding Mode Control for Stabilizing of Boost Converter in a Solid Oxide Fuel Cell

2013 ◽  
Vol 13 (4) ◽  
pp. 139-147 ◽  
Author(s):  
Junsheng Jiao
Keyword(s):  
Fuel Cell ◽  
Sliding Mode Control ◽  
Flow Rate ◽  
Output Voltage ◽  
Sliding Mode ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Hydrogen Flow Rate ◽  
Dc Voltage ◽  
Hydrogen Flow

Abstract The output voltage of Solid Oxide Fuel Cell (SOFC) is usually changed with the temperature and hydrogen flow rate. Since the fuel cell can generate a wide range of voltages and currents at the terminals, as a consequence, a constant DC voltage and function cannot be maintained by itself as a DC voltage power supply source. To solve this problem, a simple SOFC electrochemical model is introduced to control the output voltage. The Sliding Mode Control (SMC) is used to control the output voltage of the DC-DC converter for maintaining the constant DC voltage when the temperature and hydrogen flow rate are changed. By the simulation results it can be seen that the SMC technique has improved the transient response and reduced the steady state error of DC voltage.

Disilane addition versus silane-hydrogen flow rate effect on the PECVD of silicon thin films

2016 ◽  
Vol 34 (6) ◽  
pp. 061307
Author(s):  
Panagiotis Dimitrakellis ◽  
Eleftherios Amanatides ◽  
Dimitrios Mataras ◽  
Angelos G. Kalampounias ◽  
Nikolaos Spiliopoulos ◽  
...  
Keyword(s):  
Thin Films ◽  
Flow Rate ◽  
Rate Effect ◽  
Hydrogen Flow Rate ◽  
Hydrogen Flow ◽  
Silicon Thin Films ◽  
Flow Rate Effect

The Influence of Deposition Conditions on the Properties of a-Sic:H Thin Films

1990 ◽  
Vol 192 ◽  
Author(s):  
L. Magafas ◽  
D. Girginoudi ◽  
N. Georgoulas ◽  
A. Thanailakis
Keyword(s):  
Thin Films ◽  
Chemical Composition ◽  
Optical Absorption ◽  
Flow Rate ◽  
Growth Conditions ◽  
Optical Absorption Coefficient ◽  
Hydrogen Flow Rate ◽  
Hydrogen Flow ◽  
Composition Structure ◽  
Deposition Conditions

ABSTRACTThe dependence of chemical composition, structure and optoelectronic properties of sputtered a-SiC:H thin films on substrate temperature, Ts, and hydrogen flow rate has been studied. The films are amorphous for the growth conditions used in this work. The chemical composition of the alloys is very little influenced by the Ts, whereas the hydrogen content and the optical absorption coefficient depends strongly on Ts and hydrogen flow rate.

Pyrolysis and Steam Gasification of Paper and Evaluation of Paper Char Kinetics

2009 ◽  
Author(s):  
Islam Ahmed ◽  
Ashwani K. Gupta
Keyword(s):  
Flow Rate ◽  
Steam Gasification ◽  
Energy Yield ◽  
Hydrogen Yield ◽  
Hydrogen Flow Rate ◽  
Hydrogen Flow ◽  
Char Gasification ◽  
Gasification Process ◽  
Reactor Temperature ◽  
Partial Overlap

Main characteristics of gaseous yield from steam gasification have been investigated experimentally. Results of steam gasification have been compared to that of pyrolysis. The temperature range investigated were 600 to 1000°C in steps of 100°C. Results have also been obtained under pyrolysis conditions at same temperatures. For steam gasification runs, steam flow rate was kept constant at 8.0 gr./Min.. Investigated characteristics were evolution of syngas flow rate with time, hydrogen flow rate, chemical composition of syngas, energy yield and apparent thermal efficiency. Residuals from both processes were quantified and compared as well. Material destruction, hydrogen yield and energy yield is better with gasification as compared to pyrolysis. This advantage of the gasification process is attributed mainly to char gasification process. Char gasification is found to be more sensitive to the reactor temperature than pyrolysis. Pyrolysis can start at low temperatures of 400 °C; however char gasification starts at 700 °C. A partial overlap between gasification and pyrolysis exists and is presented here. This partial overlap increases with increase in temperature. As an example, at reactor temperature 800 °C this overlap represents around 27% of the char gasification process and almost 95% at reactor temperature 1000°C.

Experimental Investigation of Diesel - Hydrogen Dual Fuel Direct Injection C.I. Engine with Exhaust Gas Recirculation

2015 ◽  
Vol 787 ◽  
pp. 697-701 ◽  
Author(s):  
R. Senthil Kumar ◽  
M. Loganathan
Keyword(s):  
Flow Rate ◽  
Combustion Engine ◽  
Direct Injection ◽  
Exhaust Gas Recirculation ◽  
Nox Emission ◽  
Exhaust Gas ◽  
Hydrogen Flow Rate ◽  
Hydrogen Flow ◽  
Inlet Manifold ◽  
Gas Recirculation

Hydrogen is a zero emission alternative gaseous fuel generally used in internal combustion engine with single fuel or duel fuel mode. In this work the Hydrogen is introduced in inlet manifold in addition to main diesel fuel used in the engine. The different flow rate of hydrogen fuel is used in this work are from 2 lpm to 10 lpm at 2 bar pressure. Here the single cylinder, direct injection, diesel engine with 1500 rpm rated speed is used for test. In addition to hydrogen, the exhaust gas also introduced in the inlet manifold with various percentages namely 10% and 20%. The engine is loaded with eddy current dynamometer .The engine performance and emissions of various combination of hydrogen flow rate and exhaust gas recirculation (EGR) were analyzed. The result showed that in 8 lpm hydrogen flow rate without EGR the BTE increased and BSFC decreased. At the same condition the HC, CO emissions reduced and NOx emission is increased. But NOx emission with 10% and 20% EGR is reduced.

Sign in / Sign up

Export Citation Format

Share Document