THE EFFECT OF THE GAS INLET ON THE FLUID FIELD DURING FABRICATING HFCVD DIAMOND-COATED CUTTING TOOLS

2014 ◽  
Vol 21 (05) ◽  
pp. 1450068
Author(s):  
BIN SHEN ◽  
SULIN CHEN ◽  
LEI CHENG ◽  
FANGHONG SUN
Keyword(s):  
Initial Velocity ◽  
Coupling Effect ◽  
Cutting Tools ◽  
Chemical Vapor ◽  
Gas Velocity ◽  
Gas Field ◽  
Growth Environment ◽  
Fluid Field ◽  
Flute Surface ◽  
Simulation Results

In the present study, the fluid field in a process of fabricating diamond coated cutting tools using the hot filament chemical vapor deposition (HFCVD) method is investigated using the finite volume method (FVM), in which the effects of the inlet height, gas initial velocity, inlet radius and arrangement are illustrated in terms of the gas velocity magnitude and vector distribution near the filaments and the flute surface of cutting tools. In the simulations, the coupling effect of the temperature and the gas field is also considered by simultaneously calculating the temperature distribution. The simulation results suggest that either shortening the distance between the gas inlet and filaments, or increasing the gas initial velocity is helpful for the reactive gas arriving at filaments surface and being dissociated. Furthermore, increasing the inlet area is able to significantly increase the velocity of gas field around the filaments, as well as produce a much more uniform gas velocity field. Based on this conclusion, two novel multi-inlets setups are proposed to further improve the generated gas field and the simulation results show that the most superior gas field can be achieved with the one including 8 larger central inlets and 24 smaller outskirt inlets. Finally, an actual deposition experiment is carried out and its result indicates that adopting the optimized such inlet arrangement could generate a highly uniform and homogeneous growth environment on whole deposition area.

THE EFFECT OF THE GAS OUTLET ON THE GAS VELOCITY FIELD IN MASS-PRODUCTION OF HFCVD DIAMOND-COATED DRILLS

2014 ◽  
Vol 21 (04) ◽  
pp. 1450051
Author(s):  
BIN SHEN ◽  
LEI CHENG ◽  
FANGHONG SUN
Keyword(s):  
Velocity Field ◽  
Mass Production ◽  
Gas Flow ◽  
Critical Role ◽  
Chemical Vapor ◽  
Gas Velocity ◽  
Gas Field ◽  
Growth Environment ◽  
Fluid Field ◽  
Simulation Results

In the present study, the finite volume method (FVM) is adopted to investigate the effect of gas outlet on the fluid field generated by a hot filament chemical vapor deposition (HFCVD) setup that is designed for the mass-production of diamond coated drills. The temperature field is calculated simultaneously such that its effect on the gas flow can be included in the resulted gas velocity field. First, the effect of outlet radius (R out ) is investigated using a 2-outlets arrangement. The results show that the gas field obtained with R out = 10 mm is superior to R out = 5 mm or 15 mm, which not only can produce higher gas velocity, but also a more uniform gas field in filament plane. To further refine the uniformity of gas field outside the filament area, four 4-outlets arrangements with different combinations of the distance between gas outlets and worktable and gas inlets coverage are proposed and a comparative study on their effect on the gas field is conducted. The simulation results show that allocating two additional outlets near the worktable is beneficial for enhancing the uniformity of gas velocity field outside the filaments but slightly worsen it near the filaments. Finally, actual deposition experiments are conducted to justify the simulation results and the results suggest that the gas velocity in the drill region plays critical role on the growth rate of diamond film and the 4-outlets arrangement could provide more uniform growth environment than the 2-outlets arrangement.

Comparative Studies on the Cutting Performance of CVD Diamond and DLC Coated Inserts in Turning GFRP Composite Materials

2010 ◽  
Vol 431-432 ◽  
pp. 466-469
Author(s):  
Dong Can Zhang ◽  
Bin Shen ◽  
Fang Hong Sun ◽  
Ming Chen ◽  
Zhi Ming Zhang
Keyword(s):  
Composite Materials ◽  
Flank Wear ◽  
Arc Discharge ◽  
Cutting Tools ◽  
Chemical Vapor ◽  
Cvd Diamond ◽  
Cutting Performance ◽  
Vacuum Arc ◽  
Reinforced Plastics ◽  
Gfrp Composite

The diamond and diamond-like carbon (DLC) films were deposited on the cobalt cemented tungsten carbide (WC-Co) cutting tools respectively adopting the hot filament chemical vapor deposition (HFCVD) technique and the vacuum arc discharge with a graphite cathode. The scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD) and Raman spectroscopy were used to characterize the as-deposited diamond and DLC films. To evaluate their cutting performance, comparative turning tests were conducted using the uncoated WC-Co and as-fabricated CVD diamond and DLC coated inserts, with glass fiber reinforced plastics (GFRP) composite materials as the workpiece. The research results exhibited that diamond and DLC coated inserts had great advantages in cutting tests compared to uncoated insert. The flank wear of the CVD diamond coated insert maintained a very low value about 50μm before the cutting tool failure occurred. For the DLC coated insert, its flank wear always maintained a nearly constant value of 70~200μm during whole 45 minutes turning process. The flank wear of CVD diamond coated insert was lower than that of DLC coated insert before diamond films peeling off.

scholarly journals Interwell coupling effect in Si/SiGe quantum wells grown by ultra high vacuum chemical vapor deposition

2007 ◽  
Vol 2 (3) ◽  
pp. 149-154
Author(s):  
Rui Wang ◽  
Soon Fatt Yoon ◽  
Fen Lu ◽  
Wei Jun Fan ◽  
Chong Yang Liu ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Quantum Wells ◽  
Vapor Deposition ◽  
Coupling Effect ◽  
High Vacuum ◽  
Chemical Vapor ◽  
Ultra High Vacuum ◽  
Sige Quantum Wells

Numerical Simulation of Gas Phase Growth Environment of Carbon Nanotube Synthesis by Plasma-Enhanced Chemical Vapor Deposition

2005 ◽  
Author(s):  
R. K. Garg ◽  
J. P. Gore ◽  
T. S. Fisher
Keyword(s):  
Gas Phase ◽  
Reaction Mechanisms ◽  
Microwave Plasma ◽  
Plasma Reactor ◽  
Chemical Vapor ◽  
Synthesis Process ◽  
Phase Reaction ◽  
Phase Growth ◽  
Growth Environment ◽  
Hydrogen Mixture

The gas-phase growth environment of carbon nanotubes has been simulated using different published chemical reaction mechanisms for a gas mixture of methane and hydrogen. Detailed chemical analysis of the growth environment is important in identifying precursor species responsible for CNT formation and is useful in understanding fundamental mechanisms that ultimately could allow control of the CNT synthesis process. The present simulations seek to compare the roles of different gas phase reaction mechanisms and to identify precursors for CNT formation. The results show that inlet methane-hydrogen mixture converts primarily to a acetylene-hydrogen mixture, and C2H2, CH3, H2, and H are the main precursors formed in the plasma under experimentally verified CNT growth conditions in a microwave plasma reactor.

scholarly journals Influence of the Heat Dissipation Mode of Long-Flute Cutting Tools on Temperature Distribution during HFCVD Diamond Films

Crystals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 394
Author(s):  
Zhang ◽  
Qian ◽  
wang ◽  
Huang ◽  
Zhang ◽  
...  
Keyword(s):  
Heat Dissipation ◽  
Focal Point ◽  
Cutting Tools ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Polycrystalline Diamond ◽  
Decisive Role ◽  
Diamond Coatings ◽  
The Difference ◽  
The Individual

The distribution of substrate temperature plays a decisive role on the uniformity of polycrystalline diamond films on cemented carbide tools with a long flute, prepared by a hot filament chemical vapor deposition (HFCVD). In this work, the heat dissipation mode at the bottom of tools is a focal point, and the finite volume method (FVM) is conducted to simulate and predict the temperature field of tools, with the various materials of the holder placed under the tools. The simulation results show that the thermal conductivity of the holder affects the temperature difference of the individual tools greatly, but only affects the temperature of different tools at the same XY plane slightly. Moreover, the ceramic holder can reduce the difference in temperature of an individual tool by 54%, compared to a copper one. Afterwards, the experiments of the deposition of diamond films is performed using the preferred ceramic holder. The diamond coatings on the different positions present a highly uniform distribution on their grain size, thickness, and quality.

Analysis of Interlayer between WC–Co and CVD Diamond Film

2008 ◽  
Vol 375-376 ◽  
pp. 92-96 ◽  
Author(s):  
Wen Zhuang Lu ◽  
Dun Wen Zuo ◽  
Min Wang ◽  
Feng Xu
Keyword(s):  
Cutting Tools ◽  
Chemical Vapor ◽  
Cvd Diamond ◽  
Diamond Coatings ◽  
X Ray Diffraction ◽  
Raman Scattering Spectroscopy ◽  
Electron Probe Micro Analyzer ◽  
Mechanical Bond ◽  
Cvd Diamond Coating ◽  
Better Than

Electroplated Cr, Ni and Cu were used as interlayer for chemical vapor deposition (CVD) diamond coating on WC–Co cemented carbide cutting tools. The electroplated interlayers were studied by Scanning Electron Microscope (SEM), Electron Probe Micro Analyzer (EPMA) and X-ray diffraction (XRD). The CVD diamond coatings were studied by SEM and Raman Scattering Spectroscopy (Raman). The experimental results show that there is diffusion bonded interface between electroplated layer and WC-Co substrate after H plasma treatment, the bond between electroplated layers and WC-Co substrate changes from mechanical bond to metallurgical bond and the adhesion becomes stronger. Electroplated Cr interlayer forms new phases of Cr3C2 and Cr7C3 under CVD conditions, while electroplated Ni and Cu interlayers do not form carbides under CVD conditions. Cr carbides have good chemical compatibility to diamond, and they are propitious to diamond nucleation and growth during the deposition period. The diamond crystal microstructure, diamond quality and adhesion on Cr interlayer are better than those on electroplated Ni and Cu interlayers.

Evaluation of Silicon Nitride Ceramic Cutting Tools with Diamond Coatings

2008 ◽  
Vol 591-593 ◽  
pp. 537-542 ◽  
Author(s):  
M.A. Lanna ◽  
A.M. Abrão ◽  
F. Levy Neto ◽  
Claudinei dos Santos ◽  
Cosme Roberto Moreira Silva
Keyword(s):  
Silicon Nitride ◽  
Flank Wear ◽  
Cutting Tools ◽  
Chemical Vapor ◽  
Carbon Powder ◽  
Diamond Coating ◽  
Machining Performance ◽  
Film Rupture ◽  
Composite Surface ◽  
Ceramic Tools

There is a substantial increase on carbon-carbon composites use for engineering applications, considering its high temperature properties and low specific mass. However the machining costs are relatively high, and new cutting tools, mainly ceramics, must be developed to overcome such difficulty, aiming cost reductions. In this work, silicon nitride based ceramics has been prepared , by pressureless sintering of silicon nitride powders and appropriate amounts of Al2O3,Ce2O3, Y2O3 and AlN. Cutting tools were prepared from the sintered materials, with geometry according to ISO1832. Selected cutting tools were also diamond coated by a hot filament-assisted Chemical Vapor Deposition (HFCVD) diamond coating process. Carbon Fiber Reinforced Carbon (CFRP) composites machining was performed, to evaluate the diamond coating influence on machining performance. After the tests, the uncoated tools presented severe flank wear and shorter life than the diamond coated ceramic tools. This flank wear is caused by the abrasive carbon powder generated during the facing operation. On CVD diamond coated α-SiAlON ceramic tools, no flank wear was observed, and the cutting edge remained unmodified, even for severe test conditions, such as high cutting length and speed. Carbon particles, originated from the machined composite, do not promotes diamond film rupture, but instead, acts as lubricant film and reduces composite surface initial roughness.

Simulation of Substrate Temperature Distribution in Diamond Films Growth on Cemented Carbide Inserts by Hot Filament CVD

2007 ◽  
Vol 10-12 ◽  
pp. 864-868 ◽  
Author(s):  
Wei Zuo ◽  
Bin Shen ◽  
Fang Hong Sun ◽  
Ming Chen
Keyword(s):  
Temperature Distribution ◽  
Three Dimensional ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Deposition Parameters ◽  
Dimensional Finite Element ◽  
Simulation Results ◽  
Three Dimensional Finite Element ◽  
Hot Filament ◽  
Carbide Inserts

Three-dimensional finite element simulations were used to investigate the influences of various hot filaments and other deposition parameters on the temperature field of substrates which affect significantly the growth and quality of diamond films by hot filament chemical vapor deposition (HFCVD) and based on the simulation results, the optimum position for diamond deposition was found. In the experiment, six cemented tungsten carbide inserts were used as substrates and placed on the workbench in the CVD reactor to deposit diamond films. According to the temperature distribution on substrates measured by thermocouple fixed in CVD reactor, the simulations were validated and the optimum arrangement of substrates was established from the simulation results. In addition, the simulation model was altered to optimize the process parameters of HFCVD deposition, and an improved process of depositing diamond films with high quality was obtained in order to achieve the great surface morphology, which laid the foundation of developing a new method to arrange the substrates in the CVD reactor for depositing diamond films.

The Simulation of Polycrystalline Silicon Thin Film Deposition in PECVD System

2011 ◽  
Vol 189-193 ◽  
pp. 2032-2036 ◽  
Author(s):  
Zhi Jian Wang ◽  
Xiao Feng Shang
Keyword(s):  
Thin Film ◽  
Deposition Rate ◽  
Polycrystalline Silicon ◽  
Chemical Vapor ◽  
Thin Film Deposition ◽  
Deposition Process ◽  
Film Deposition ◽  
Main Reaction ◽  
Silicon Thin Film ◽  
Simulation Results

Taking Silicon tetrachloride (SiCl4) and hydrogen (H2) as the reaction gas, by the method of plasma-enhanced chemical vapor deposition (PECVD), this paper simulates the deposition process of polycrystalline silicon thin film on the glass substrates in the software FLUENT. Three dimensional physical model and mathematics model of the simulated area are established. The reaction mechanism including main reaction equation and several side equations is given during the simulation process. The simulation results predict the velocity field, temperature distribution, and concentration profiles in the PECVD reactor. The simulation results show that the deposition rate of silicon distribution is even along the circumference direction, and gradually reduced along the radius direction. The deposition rate is about 0.005kg/(m2•s) at the center. The simulated result is basically consistent with the practical one. It means that numerical simulation method to predict deposition process is feasible and the results are reliable in PECVD system.

Sign in / Sign up

Export Citation Format

Share Document