Modeling of Thermal Stresses in Composite Diamond Coatings and Mechanisms of Improvement of Adhesion

1994 ◽  
Vol 356 ◽  
Author(s):  
W. D. Fan ◽  
K. Jagannadham ◽  
J. Narayan
Keyword(s):  
Thermal Stresses ◽  
Composite Coatings ◽  
Composite Layer ◽  
Single Layer ◽  
Diamond Coating ◽  
Diamond Coatings ◽  
Element Analysis ◽  
Composite Layers ◽  
Composite Diamond ◽  
Stress Influences

AbstractThermal stress influences adhesion of many coatings applied on tool substrates. Management of thermal stresses is important for improvement of coatings and tool life. We have shown that stresses can be controlled by developing a composite layer of diamond with carbides and nitrides such as TiC or TiN. We have modeled the thermal stresses in these composite diamond coatings using finite element analysis. The composite diamond coatings consist of a discontinuous layer of diamond with an embedded layer of TiC or TiN, and a top layer of continuous diamond. For comparison, a single layer of diamond coating has also been used. The thermal stresses in these coatings on WC(Co) and Si3N4 tool substrates were calculated. Results show that the thermal stresses at the interface between the coatings and the substrate are relaxed after introducing the composite layers. This stress relaxation is responsible for the improvement of the adhesion of composite coatings.

Improvement of Adhesion of Diamond Coatings to WC(CO) Tool Substrates

1994 ◽  
Vol 363 ◽  
Author(s):  
W. D. Fan ◽  
K. Jagannadham ◽  
J. Narayan
Keyword(s):  
Diamond Film ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Composite Coatings ◽  
Composite Layer ◽  
Chemical Vapor ◽  
Wear Test ◽  
Ceramic Coatings ◽  
Diamond Coatings ◽  
Composite Layers

AbstractAdhesion of diamond coatings to cutting tool substrates is an important property that is needed to replace the polycrystalline diamond tools (PCD) in machine tool applications. The improvement in adhesion of diamond on WC(Co) tool substrates is brought about by formation of a composite layer. Composite layers made up of TiC or TiN and diamond were formed by laser physical vapor deposition of ceramic coatings and hot filament chemical vapor deposition of diamond films. A first layer of discontinuous diamond film on WC is embedded in the ceramic coatings followed by growth of a continuous diamond film that maintains continuity with the first diamond layer. The composite coatings were characterized by SEM and Raman spectroscopy. Adhesion and wear resistance of the diamond coatings were measured using a polishing wear test. The mechanisms of improvement in adhesion were analyzed by finite element modeling. Results show that TiC composite layers improve the adhesion of diamond coatings significantly. This improvement is considered to arise from the modification of the thermal stress at the interface between the diamond film and the WC(Co) tool substrate.

Diamond-ceramic composite tool coatings

1994 ◽  
Vol 9 (11) ◽  
pp. 2850-2867 ◽  
Author(s):  
W.D. Fan ◽  
X. Chen ◽  
K. Jagannadham ◽  
J. Narayan
Keyword(s):  
Wear Resistance ◽  
Diamond Film ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Thermal Stresses ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Diamond Coatings ◽  
Composite Layers ◽  
Composite Diamond

We have developed multilayer composite diamond coatings with improved adhesion and wear resistance on WC(Co) tool substrates. The coatings consist of a first layer of discontinuous diamond crystallites that are anchored to the WC(Co) substrate by an interposing layer of ceramic films. These films consist of TiC, TiN, SiC, Si3N4 or WC deposited to provide a conformal coverage on the first layer of diamond. A second or final layer of continuous diamond film is deposited to provide the cutting edge of the tool. The diamond film in the composite layers is deposited by hot filament chemical vapor deposition (HFCVD) and the interposing layer is deposited by laser physical vapor deposition (LPVD). The different parameters associated with the deposition of diamond and interposing layers are optimized to improve the adhesion and wear resistance. We have studied the adhesion characteristics by indentation tests in which the critical load for peeling of the diamond films is determined. Adhesion and wear resistance of the films are also tested using an overlap polishing on diamond paste with 5–6 μm particle size. The diamond and interposing layers in the composite are characterized by scanning electron microscopy and Raman spectroscopy. Results of improvement in adhesion and wear resistance are correlated with the quality of the diamond film and the interposing layer. Better accommodation of thermal stresses and strains in the composite layers has been shown to be responsible for improvement in the adhesion and wear resistance of the composite diamond films.

Residual Stresses in Single and Multilayer Composite Diamond Coatings

1996 ◽  
Vol 458 ◽  
Author(s):  
K. Jagannadham ◽  
T. R. Watkims ◽  
J. Narayan
Keyword(s):  
Residual Stresses ◽  
Single Layer ◽  
Chemical Vapor ◽  
Diamond Coating ◽  
Diamond Coatings ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Types ◽  
Composite Diamond ◽  
Hot Filament

ABSTRACTResidual stresses were measured in different types of diamond coatings deposited onto molybdenum substrates by hot filament chemical vapor deposition. The types of coatings examined include a continuous single layer diamond coating and a continuous multilayer diamond composite coating with an aluminum nitride embedding layer. The stresses were determined by X-ray diffraction and Raman spectroscopy and compared.

Silicon Nitride Tools Coated With Tic Or Tin Composite Diamond Structures

1995 ◽  
Vol 415 ◽  
Author(s):  
W.D. Fan ◽  
K. Jagannadham ◽  
J. Narayan
Keyword(s):  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Diamond Coating ◽  
Diamond Coatings ◽  
Adhesion Properties ◽  
Tin Films ◽  
Composite Diamond ◽  
Diamond Paste

ABSTRACTComposite diamond coatings on Si3N4 substrates have been developed to minimize stresses/strains and improve wear and adhesion properties. The coatings consist of a first layer of discontinuous diamond crystallites which are anchored to the Si3N4 substrate by a second interposing layer of TiC or TiN film. A top third layer of continuous diamond film is grown epitaxially on the first layer. The diamond films and TiC or TiN films were deposited using hot filament chemical vapor deposition and laser physical vapor deposition, respectively. The TiC and TiN films were examined by X-ray diffraction. The diamond films were characterized by scanning electron microscopy and Raman spectroscopy. Adhesion of the diamond coatings was investigated using overlap polishing with diamond paste, wear against Al-12.5%Si alloy, and pull-test. The results show that after introducing an interposing layer of TiC or TiN, adhesion of diamond coatings on Si3N4 substrates is improved significantly. After polishing test against diamond paste for 4 hours, only 30% of diamond was retained with single diamond coating while 80% of diamond was found with TiN composite diamond coating. The mechanism of improvement of adhesion is discussed.

Thermal stress prediction in mirror and multilayer coatings

2015 ◽  
Vol 22 (2) ◽  
pp. 317-327 ◽  
Author(s):  
Xianchao Cheng ◽  
Lin Zhang ◽  
Christian Morawe ◽  
Manuel Sanchez del Rio
Keyword(s):  
Finite Element ◽  
Liquid Nitrogen ◽  
Thermal Stresses ◽  
Single Layer ◽  
Element Model ◽  
Critical Issue ◽  
X Rays ◽  
Element Analysis ◽  
Thermal Expansion Coefficients ◽  
Liquid Nitrogen Cooling

Multilayer optics for X-rays typically consist of hundreds of periods of two types of alternating sub-layers which are coated on a silicon substrate. The thickness of the coating is well below 1 µm (tens or hundreds of nanometers). The high aspect ratio (∼107) between the size of the optics and the thickness of the multilayer can lead to a huge number of elements (∼1016) for the numerical simulation (by finite-element analysis usingANSYScode). In this work, the finite-element model for thermal-structural analysis of multilayer optics has been implemented using theANSYSlayer-functioned elements. The number of meshed elements is considerably reduced and the number of sub-layers feasible for the present computers is increased significantly. Based on this technique, single-layer coated mirrors and multilayer monochromators cooled by water or liquid nitrogen are studied with typical parameters of heat-load, cooling and geometry. The effects of cooling-down of the optics and heating of the X-ray beam are described. It is shown that the influences from the coating on temperature and deformation are negligible. However, large stresses are induced in the layers due to the different thermal expansion coefficients between the layer and the substrate materials, which is the critical issue for the survival of the optics. This is particularly true for the liquid-nitrogen cooling condition. The material properties of thin multilayer films are applied in the simulation to predict the layer thermal stresses with more precision.

Effects of Two-Step DC Electrochemical Pretreatment of Fine Grinding WC-Co Tool Surface on Morphology and Quality of Diamond Coatings

2011 ◽  
Vol 337 ◽  
pp. 59-62
Author(s):  
Xiang Hui Zhang ◽  
Ling Wang ◽  
Jian Ping Long
Keyword(s):  
Surface Morphology ◽  
Direct Current ◽  
Arc Discharge ◽  
Etching Time ◽  
Diamond Coating ◽  
Diamond Coatings ◽  
Fine Grinding ◽  
Electrolytic Etching ◽  
Electrochemical Pretreatment

In the present investigation, diamond coating was deposited on fine grinding cemented carbide substrate by direct current arc discharge chemical vapor deposition. The effect of electrolytic etching time in the two-step electrochemical pretreatment process (firstly using electrolytic etching, and then using acid etching) on morphology and quality of the diamond coating were systemically studied. The surface morphology feature and quality of diamond coatings were characterized by means of Scanning Electron Microscope (SEM), laser Raman spectrometer respectively. The results showed that the electrolytic etching duration has distinctly effect on the quality and crystal features such as morphology, crystal type and grain size of diamond coating. It showed that as electrolytic current is direct current 3A, electrolytic etching time altering from 0.5 min to 7.5min, the surface morphology of diamond films gradually transition from microcrystalline cubic-octahedron to cauliflower type nanocluster, and further increase the electrolytic etching time, will lead to several negative effects on the quality and nucleation of the coatings which is not only retard the diamond nucleation, but also promote the formation of graphite.

Finite Element Analysis of Thermal Stresses in Circumferential Cast Clasps of Removable Partial Dentures

2007 ◽  
Vol 23 ◽  
pp. 229-232
Author(s):  
Liliana Sandu ◽  
Nicolae Faur ◽  
Cristina Bortun ◽  
Sorin Porojan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Stresses ◽  
Element Analysis ◽  
3 Dimensional ◽  
Thermal Changes ◽  
The Finite Element Analysis ◽  
Dimensional Finite Element ◽  
Back Action ◽  
Aggressive Effect

Several studies evaluated the removable partial dentures by the finite element analysis, but none of them evaluated thermal stresses. The purpose of the study was to explore the influence of thermal oral changes induced by hot/cold liquids and food on the circumferential cast clasps of removable partial dentures. A 3-dimensional finite element method was used to explore the temperature distribution, thermal stress and the influence of thermal changes on stresses and displacements of circumferential clasps during functions. Thermal variations induce stresses in dental clasps, high temperatures having a more aggressive effect than lower one. Cold liquids and food induce high stresses in the retentive clasp arms while hot ones in the occlusal rests of the clasps and for the back action clasp also in the minor connector. The study suggests the importance of consFigureidering thermal variations for stress analyses of the cast clasps.

Three Turnaround Heat Treating Studies

2003 ◽  
Author(s):  
Jaan Taagepera ◽  
Marty Clift ◽  
D. Mike DeHart ◽  
Keneth Marden
Keyword(s):  
Heat Treatment ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Stress ◽  
Thermal Stresses ◽  
Heat Treating ◽  
Element Analysis ◽  
Stress Profiles ◽  
Insight Into

Three vessel modifications requiring heat treatment were analyzed prior to and during a planned turnaround at a refinery. One was a thick nozzle that required weld build up. This nozzle had been in hydrogen service and required bake-out to reduce the potential for cracking during the weld build up. Finite element analysis was used to study the thermal stresses involved in the bake-out. Another heat treatment studied was a PWHT of a nozzle replacement. The heat treatment band and temperature were varied with location in order to minimize cost and reduction in remaining strength of the vessel. Again, FEA was used to provide insight into the thermal stress profiles during heat treatment. The fmal heat treatment study was for inserting a new nozzle in a 1-1/4Cr-1/2Mo reactor. While this material would ordinarily require PWHT, the alteration was proposed to be installed without PWHT. Though accepted by the Jurisdiction, this nozzle installation was ultimately cancelled.

Influence of Technical Parameters on the Residual Stress in the Diamond Coating

2012 ◽  
Vol 426 ◽  
pp. 85-88
Author(s):  
Hong Xiang Wang ◽  
Dun Wen Zuo ◽  
Chun Xu ◽  
Chun Zhou
Keyword(s):  
Residual Stress ◽  
Substrate Temperature ◽  
Compressive Stress ◽  
Crystalline Silicon ◽  
Volume Ratio ◽  
Chemical Vapor ◽  
Chamber Pressure ◽  
Diamond Coating ◽  
Diamond Coatings ◽  
Technical Parameters

The diamond coatings were prepared by hot filament chemical vapor deposition(HFCVD) on the mono-crystalline silicon substrates. The influence of the technical parameters such as methane volume ratio, substrate temperature and reaction pressure on the residual stress in the diamond coating was studied. The results showed that the residual stress in the coating was compressive stress in the range of parameters studied, and too high or too low substrate temperature, chamber pressure and methane volume ratio would all increase the residual compressive stress. This relationship can be explained by the influence of amorphous carbon content, vacancy density and grain size on the residual stress.

Elastic Thermal Stresses in Bimetallic Pipe Welds

1980 ◽  
Vol 102 (4) ◽  
pp. 430-432 ◽  
Author(s):  
R. D. Blevins
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Intensity ◽  
Maximum Stress ◽  
Thermal Stresses ◽  
Simple Expression ◽  
Element Analysis ◽  
Maximum Stress Intensity ◽  
Bimetallic Pipe ◽  
Uniform Change

The elastic thermal stresses in a welded transition between two pipes of the same size but different alloys are explored. A stress-free temperature is postulated and the stress due to a uniform change in temperature is characterized by the maximum stress intensity in the weld. A simple expression for predicting this maximum stress intensity is developed based on the results of finite element analysis.

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