CVD Diamond Films as Wear-Resistant Coatings for Relief Valve Components in the Coal Liquefaction Equipment

2011 ◽  
Vol 175 ◽  
pp. 219-225 ◽  
Author(s):  
Xin Chang Wang ◽  
Bin Shen ◽  
Fang Hong Sun
Keyword(s):  
Fluid Velocity ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Cvd Diamond ◽  
Coal Liquefaction ◽  
Valve Seat ◽  
Relief Valve ◽  
Wear Resistant ◽  
Mechanical And Tribological Properties ◽  
Hot Filament

Relief valves used in the coal liquefaction equipment are running in an extremely harsh environment with extraordinarily high temperature, high pressure differential, high fluid velocity as well as the intensely slurry flow erosion. The lifetime of relief valves is critically important to the reliability and running cost of the coal liquefaction equipment. Diamond film is potentially used as wear-resistant and protective coating for the relief valve components in coal liquefaction equipment due to its outstanding mechanical and tribological properties. In present study, a layer of high-quality diamond films are deposited on the working surface of conventional WC-Co cemented carbide relief valve components, using the hot filament chemical vapor deposition (HFCVD) technique. Two different types of hot filament arrangements are respectively adopted for depositing diamond films on the interior surface of valve seat and outer surface of valve spool. The fabricated CVD diamond coated relief valve components are characterized using Scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD), and Raman spectroscopy. The results exhibit that working surfaces of both valve seat and spool are covered by a layer of continuous, homogeneous diamond films on which well-faceted diamond grains with grain size of ~2-3 μm distribute. Furthermore, the fabricated relief valve components are equipped on a coal liquefaction facility and their performance is evaluated in real production. The results present that the working lifetime is largely elongated up to ~1200 hours, as more than three times as that of conventional tungsten carbide valve components.

Improvement on the Cutting Performance of CVD Diamond Coated Drills in Drilling CFRP

2012 ◽  
Vol 499 ◽  
pp. 366-371 ◽  
Author(s):  
Jian Guo Zhang ◽  
Ben Wang ◽  
Fang Hong Sun ◽  
Hang Gao
Keyword(s):  
Thermal Conductivity ◽  
Wear Resistance ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Cvd Diamond ◽  
Cutting Performance ◽  
Reinforced Plastics ◽  
Coated Tool ◽  
Hot Filament

Carbon fiber reinforced plastics (CFRP) is difficult to machine because of the extremely abrasive nature of the carbon fibers and its low thermal conductivity. CVD diamond films have many excellent properties such as wonderful wear resistance, high thermal conductivity and low friction coefficient, therefore depositing diamond films on the surface of drills is thought to be an effective way to elongate the lifetime of drills and improve the cutting performance. In this study, diamond films are deposited on the WC-Co drill using hot filament chemical vapor deposition (HFCVD) method. The results of characterization by the scanning electron microscope (SEM) and Raman spectrum indicate that the fabricated CVD diamond coated drill is covered with a layer of uniform and high-purity diamond films. The cutting performance of as-fabricated CVD diamond coated drill is evaluated in dry drilling CFRP, comparing with the uncoated WC-Co drill. The results demonstrate that the CVD diamond coated drill exhibits much stronger wear resistance. Its flank wear is about 50μm after drilling 30 holes, about one-third of that of WC-Co drill. Machining quality of the exit and internal wall of drilled holes shows better surface finish obtained by coated drill, which suggests that CVD diamond coated tool has great advantages in drilling CFRP.

scholarly journals The Hydrogenation Impact on Electronic Properties of p-Diamond/n-Si Heterojunctions

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6615
Author(s):  
Szymon Łoś ◽  
Kazimierz Fabisiak ◽  
Kazimierz Paprocki ◽  
Mirosław Szybowicz ◽  
Anna Dychalska ◽  
...  
Keyword(s):  
Diamond Films ◽  
Chemical Vapor ◽  
Polycrystalline Diamond ◽  
Cvd Diamond ◽  
Point Of View ◽  
Hydrogen Passivation ◽  
Temperature Dependent ◽  
Current Voltage ◽  
P Type ◽  
Hot Filament

The undoped polycrystalline diamond films (PDFs) have been deposited on n-type silicon (Si) by Hot Filament Chemical Vapor Deposition (HF CVD) technique. The reaction gases are a mixture of methane and hydrogen. The obtained PDFs were characterized by scanning electron microscopy (SEM) and Raman spectroscopy which, in addition to the diamond phase, also confirms the presence of sp2 hybridized carbon bonds. As-grown CVD diamond layers are hydrogen terminated and show p-type conductivity. The effect of the level of hydrogenation on the electrical properties of p-diamond/n-Si heterojunctions has been investigated by temperature dependent current–voltage (J-V/T) characteristics. The obtained results suggest that the energy distribution of interface states at the grain boundary (GB) subjected to hydrogenation becomes shallower, and the hole capture cross-section can be reduced. Hydrogenation can lead to a significant reduction of the GB potential barrier. These results can be interesting from the point of view of hydrogen passivation of GBs in microelectronics.

Selective Growth of B-Doped Diamond on Si-Doped Diamond Film

2012 ◽  
Vol 217-219 ◽  
pp. 1013-1017
Author(s):  
Y.X. Cui ◽  
B. Shen ◽  
F.H. Sun ◽  
Z.M. Zhang
Keyword(s):  
Diamond Film ◽  
Sacrificial Layer ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Cvd Diamond ◽  
Selective Area ◽  
Si Doped ◽  
Cvd Diamond Film ◽  
Hot Filament ◽  
Area Deposition

Si doped CVD diamond films are prepared on Si substrate by means of hot filament chemical vapor deposition (HFCVD) through adding tetraethoxysilane (TEOS) into acetone as source of reactant gas during the growth process. The samples of diamond films are investigated by scanning electron micrograph (SEM), Raman spectrum, X-ray diffractometry (XRD) and surface profiler. The experimental results show that compared with pure diamond film, Si doped CVD diamond film exhibits grain refinement and smoother surface. Then selective area deposition (SAD) of B-doped diamond films are achieved on both Si doped CVD diamond film and pure CVD diamond film with silicon dioxide layer as sacrificial layer. SEM investigation demonstrates that the boundary of patterning on pure diamond film is rather fuzzy while on pure diamond film it is trim and distinct, which is mainly attributed to the relatively low surface roughness.

Tribological Properties of CVD Diamond Films against Graphite

2016 ◽  
Vol 689 ◽  
pp. 86-90
Author(s):  
Xue Cai Lei ◽  
Ke Pang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Raman Spectroscopy ◽  
Vapor Deposition ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Cvd Diamond ◽  
Frictional Coefficients ◽  
Hot Filament ◽  
Scanning Electron

In this investigation, micro crystalline diamond (MCD) and nanocrystalline diamond (NCD) films are deposited on cemented carbide (WC-Co) balls by hot filament chemical vapor deposition (HFCVD) technique. After deposition, MCD and NCD films are characterized by field emission scanning electron microscopy (FESEM) and Raman spectroscopy. Then frictional tests are carried out between CVD diamond coated balls and graphite. The results show that the MCD-graphite and NCD-graphite tribo-pairs exhibit comparable frictional coefficients, while the wear rate of graphite in MCD-graphite working pair is much higher than that of graphite in NCD-graphite working pair. Furthermore, the element oxygen is detected in the wear groove of graphite, suggesting the oxycarbide of working materials at the increased temperature due to the heat generated from the mechanical friction.

Deposition and Application of CVD Diamond Films on the Interior-Hole Surface of Silicon Carbide Compacting Dies

2012 ◽  
Vol 499 ◽  
pp. 45-50 ◽  
Author(s):  
Xin Chang Wang ◽  
Bin Shen ◽  
Fang Hong Sun ◽  
Z.M. Zhang ◽  
H.S. Shen ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Surface Quality ◽  
High Surface ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Cvd Diamond ◽  
High Wear Resistance ◽  
X Ray Diffraction ◽  
High Surface Quality ◽  
Hot Filament

Silicon carbide (SiC) is a promising material for fabricating wire compacting dies due to its advantages of light weight and even high wear resistance over the tungsten carbide, which currently is the most popular material used to produce compacting dies. In present study, a layer of CVD diamond film is deposited on the interior-hole surface of compacting dies using the hot filament chemical vapor deposition (HFCVD) method, following by a surface polish process, aiming at further elongating the lifetime of compacting dies and improving the surface quality of produced wires. The characterization of both as-deposited and polished CVD diamond films is employed by scanning electron microscopy (SEM), surface profiler, Raman spectroscopy and X-ray diffraction (XRD) spectroscopy. Furthermore, the performance of as-fabricated CVD diamond coated compacting dies is examined in the real production process. The results exhibit that the as-deposited CVD diamond films are homogeneous and their surface finish is significantly smoothened after the surface polish process. As compared with the conventional compacting dies, the working lifetime of the diamond coated SiC compacting dies can be increased by a factor of above 15 and in the course of processing, copper stranded wires with high surface quality and uniform sectional area can be obtained.

Cutting Performances of Diamond Coated Milling Tools in Machining Aluminum Alloy

2011 ◽  
Vol 188 ◽  
pp. 122-127
Author(s):  
Liang Wang ◽  
Jian Guo Zhang ◽  
Bin Shen ◽  
Fang Hong Sun
Keyword(s):  
Aluminum Alloy ◽  
Early Stage ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Cvd Diamond ◽  
Dry Milling ◽  
Diamond Coating ◽  
Workpiece Material ◽  
Hot Filament ◽  
Milling Tools

CVD diamond films are deposited on cobalt cemented tungsten carbide (WC-Co) endmills using hot filament chemical vapor deposition (HFCVD) method. Scanning electron microscope (SEM) and Raman spectroscopy are used to characterize the as-deposited diamond films. To evaluate the cutting performances of as-fabricated CVD diamond coated endmills, dry milling tests are conducted using aluminum alloy as the workpiece material. The uncoated WC-Co endmills are also adopted in the milling tests for the sake of comparability. The experimental results show that the build-up edge formed on the uncoated WC-Co endmills at very early stage of the cutting tests. Comparatively, CVD diamond coated endmills present an excellent anti-adhering property. The result suggests that depositing diamond coating on WC-Co endmills is a viable way to improve their cutting performances in machining of aluminum alloy materials

FRICTION PROPERTIES OF POLISHED CVD DIAMOND FILMS SLIDING AGAINST DIFFERENT METALS

2016 ◽  
Vol 23 (02) ◽  
pp. 1550096 ◽  
Author(s):  
ZICHAO LIN ◽  
FANGHONG SUN ◽  
BIN SHEN
Keyword(s):  
Stainless Steel ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Cvd Diamond ◽  
Hydrogen Gas ◽  
Friction Coefficients ◽  
Mechanical And Tribological Properties ◽  
Carbide Steel ◽  
Steel Balls ◽  
Drawing Dies

Owing to their excellent mechanical and tribological properties, like the well-known extreme hardness, low coefficient of friction and high chemical inertness, chemical vapor deposition (CVD) diamond films have found applications as a hard coating for drawing dies. The surface roughness of the diamond films is one of the most important attributes to the drawing dies. In this paper, the effects of different surface roughnesses on the friction properties of diamond films have been experimentally studied. Diamond films were fabricated using hot filament CVD. The WC-Co (Co 6[Formula: see text]wt.%) drawing dies were used as substrates. A gas mixture of acetone and hydrogen gas was used as the feedstock gas. The CVD diamond films were polished using mechanical polishing. Polished diamond films with three different surface roughnesses, as well as the unpolished diamond film, were fabricated in order to study the tribological performance between the CVD diamond films and different metals with oil lubrication. The unpolished and polished CVD diamond films are characterized with scanning electron microscope (SEM), atomic force microscope (AFM), surface profilometer, Raman spectrum and X-ray diffraction (XRD). The friction examinations were carried out by using a ball-on-plate type reciprocating friction tester. Low carbide steel, stainless steel, copper and aluminum materials were used as counterpart balls. Based on this study, the results presented the friction coefficients between the polished CVD films and different metals. The friction tests demonstrate that the smooth surface finish of CVD diamond films is beneficial for reducing their friction coefficients. The diamond films exhibit low friction coefficients when slid against the stainless steel balls and low carbide steel ball, lower than that slid against copper ball and aluminum ball, attributed to the higher ductility of copper and aluminum causing larger amount of wear debris adhering to the sliding interface and higher adhesive strength between the contacting surfaces.

Examination of the material properties and performance of thin-diamond film cutting tool inserts produced by arc-jet and hot filament chemical vapor deposition

1996 ◽  
Vol 11 (7) ◽  
pp. 1765-1775 ◽  
Author(s):  
James M. Olson ◽  
Michael J. Dawes
Keyword(s):  
Wear Resistance ◽  
Chemical Vapor Deposition ◽  
Diamond Film ◽  
Vapor Deposition ◽  
Cutting Tool ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Polycrystalline Diamond ◽  
And Performance ◽  
Hot Filament

Thin diamond film coated WC-Co cutting tool inserts were produced using arc-jet and hot-filament chemical vapor deposition. The diamond films were characterized using SEM, XRD, and Raman spectroscopy to examine crystal structure, fracture mode, thickness, crystalline orientation, diamond quality, and residual stress. The performance of the tools was evaluated by comparing the wear resistance of the materials to brazed polycrystalline diamond-tipped cutting tool inserts (PCD) while machining A390 aluminum (18% silicon). Results from the experiments carried out in this study suggest that the wear resistance of the thin diamond films is primarily related to the grain boundary strength, crystal orientation, and the density of microdefects in the diamond film.

Crystalline perfection of chemical vapor deposited diamond films

1990 ◽  
Vol 5 (8) ◽  
pp. 1591-1594 ◽  
Author(s):  
A. V. Hetherington ◽  
C. J. H. Wort ◽  
P. Southworth
Keyword(s):  
Grain Boundaries ◽  
Microwave Plasma ◽  
Diamond Films ◽  
Stacking Faults ◽  
Chemical Vapor ◽  
Cvd Diamond ◽  
Growth Conditions ◽  
Crystalline Perfection ◽  
Planar Defects ◽  
Chemical Vapor Deposited

The crystalline perfection of microwave plasma assisted chemical vapor deposited (MPACVD) diamond films grown under various conditions has been examined by TEM. Most CVD diamond films thus far reported contain a high density of defects, predominantly twins and stacking faults on {111} planes. We show that under appropriate growth conditions, these planar defects are eliminated from the center of the crystallites, and occur only at grain boundaries where the growing crystallites meet.

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