scholarly journals Contribution of Titanium, Chromium and Carbon Buffer Interlayers to Bio-Tribological Properties of Multilayer Composites

2016 ◽  
Vol 61 (3) ◽  
pp. 1391-1398
Author(s):  
Ł Major ◽  
M. Janusz ◽  
J. M. Lackner ◽  
B. Major
Keyword(s):  
Protective Coatings ◽  
Multilayer Coating ◽  
Outer Part ◽  
Mechanical Tests ◽  
Transmission Electron ◽  
Multilayer Composites ◽  
Before And After ◽  
Artificial Vessel ◽  
Means Of Transmission ◽  
Ball On Disc

Abstract Research studies on bio-tribological protective coatings of titanium, chromium and carbon based have been performed. Thin films were fabricated by hybrid PLD technique (PLD supported by magnetron sputtering). Coatings consisted of two parts; the inner part (first from the substrate) in each case was formed by titanium or chromium/titanium nitride or chromium nitride (Ti/TiN or Cr/Cr2N). The outer part was formed by pure DLC or multilayer DLC/Ti or Cr. No delamination was found at the interface. Titanium or chromium metallic layer was deposited as a first layer directly on the metallic substrate to avoid delamination. All individual layers were built of columnar nano-crystallites. Mechanisms of the mechanical wear of analyzed systems were presented, focusing on the cracking propagation in ball-on-disc tests using an 1 N and 5 N applied loads for 5 000 cycles. Complex microstructure analysis of presented nano-multilayer coatings, before and after mechanical tests, were performed by means of transmission electron microscopy (TEM). The highest stress concentration during mechanical uploading was moved through the multilayer coating by breaking only one layer at the time. The microstructure characterization revealed that cracking propagating in the outer part of the coating was stopped at the interface. In the case of the inner part of the coating Ti/TiN; Cr/Cr2N, ceramic layers showed brittle cracking, while metallic (Ti or Cr) ones deformed plastically. Fabricated coatings were subjected under the analysis in the biomechanical system optimized to test for the direct contact with a human whole blood. The study considered physiological conditions mainly related to the temperature and humidity and the frequency of cyclic deformation of the artificial vessel into which the tested sample was introduced.

scholarly journals First-Principles Calculations and Experimental Study of H+-Irradiated Zr/Nb Nanoscale Multilayer System

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 627
Author(s):  
Roman Laptev ◽  
Leonid Svyatkin ◽  
Dmitriy Krotkevich ◽  
Ekaterina Stepanova ◽  
Natalia Pushilina ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Multilayer Coating ◽  
Optical Emission ◽  
Positron Beam ◽  
Binding Energies ◽  
Emission Spectrometry ◽  
First Principles Calculations ◽  
Transmission Electron ◽  
Before And After

Nanoscale multilayer coating (NMC) based on Zr/Nb layers (100/100 nm) before and after H+ irradiation was investigated by combining experimental techniques with first-principles calculations. Detailed studies of structural and phase state and defect structure of Zr/Nb NMC were performed using methods of transmission electron microscopy, X-ray structural analysis, glow discharge optical emission spectrometry, and the Doppler broadening spectroscopy using variable energy positron beam. The first-principles calculations of binding energies for hydrogen in metal Zr/Nb layers was carried out by the pseudopotential method within the density functional theory framework. First-principles calculations and experimental data indicate the presence of macro- and microstrains predominantly in the zirconium layers of Zr/Nb NMC. The main feature of the studied Zr/Nb NMC is the predominant hydrogen localization in Zr layers near the interfaces. The annihilation of positrons is shown to occur mainly in the Zr layers in the vicinity of the interface.

scholarly journals Application of methods of ion-vacuum modification of working surfaces of carbide tools to improve their performance

2020 ◽  
Author(s):  
Ю.М. Зубарев ◽  
А.И. Круглов ◽  
М.А. Афанасенков
Keyword(s):  
Chemical Elements ◽  
Multilayer Coating ◽  
Experimental Studies ◽  
Mechanical Tests ◽  
Point Of View ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Cutting Zone ◽  
Fine Turning

В статье описаны механизмы разрушения кромок твердосплавных инструментов под влиянием сил резания в процессе обработки заготовок и воздействия окружающей среды. Рассмотрены варианты разрушения твердосплавных инструментов при обработке без применения СОТС в зоне резания. Приведен анализ основных причин потери работоспособности инструментов из металлокерамических твердых сплавов на операциях чистового точения и растачивания. Приведен анализ многокомпонентных покрытий, в состав которых входят различные комбинации химических элементов, с точки зрения их применимости в различных условиях обработки с учетом имеющихся недостатков таких покрытий. Представлена структура многослойного покрытия, позволяющая увеличить работоспособность металлокерамических твердосплавных инструментов в процессе механической обработки заготовок. Приведены результаты комплексных теоретических и экспериментальных исследований с применением современных методов компьютерного моделирования, рентгеноструктурного анализа, оптической и просвечивающей электронной микроскопии, а так же механических испытаний. The article describes the mechanisms of destruction of the edges of carbide tools under the influence of cutting forces in the processing of workpieces and environmental influences. The options for the destruction of carbide tools during processing without the use of SOTS in the cutting zone are considered. The analysis of the main reasons for the loss of operability of tools made of cermet carbides in the operations of fine turning and boring is given. The analysis of multicomponent coatings, which include various combinations of chemical elements, from the point of view of their applicability in various processing conditions, taking into account the existing disadvantages of such coatings, is given. The structure of a multilayer coating is presented, which allows to increase the performance of cermet carbide tools in the process of machining workpieces. The results of complex theoretical and experimental studies using modern methods of computer simulation, X-ray diffraction analysis, optical and transmission electron microscopy, as well as mechanical tests are presented.

TEM Analysis of Wear of Ti/TiN Multi-Layer Coating in Ball-on-Disc Test

2009 ◽  
Vol 409 ◽  
pp. 123-127 ◽  
Author(s):  
Łukasz Major ◽  
Jerzy Morgiel
Keyword(s):  
Ion Beam ◽  
Multilayer Coating ◽  
Wear Test ◽  
Layer By Layer ◽  
Tem Analysis ◽  
Thin Foils ◽  
Transmission Electron ◽  
Ball Diameter ◽  
Focus Ion Beam ◽  
Ball On Disc

The wear mechanisms of Ti/TiN eight layered coatings ( =250nm) were investigated with ball-on-disc test. The coatings were obtained by hybrid pulsed laser deposition (PLD) technique. The wear test was done using Al2O3 ball-on-disc test at 1N/2000 cycles. Thin foils for TEM observations were cut from wear track using a Quanta 200 3D FIB (Focus Ion Beam) equipped with an Omniprobe lift-up system. The microstructure investigations were performed with the TECNAI G2 SuperTWIN FEG (200kV) transmission electron microscope. At the start of the wear the load applied to Al2O3 ball resulted in pushing-in of the coating into substrate causing its grooving of the shape corresponding to the ball diameter. The lining of the crater required strong coating deformation, which was plastic within Ti and mostly brittle in TiN layers. The vertical cracks in TiN were indeed stopped at the TiN/Ti interfaces, but reopen in lying below TiN layers. In applied wear conditions the continuity of Ti layers prevails over cracking of the TiN layers and resulted in layer-by-layer wear of investigated multilayer coating.

AEM-investigation of ceramic coatings on hard metals

1990 ◽  
Vol 48 (4) ◽  
pp. 1034-1035
Author(s):  
P. Warbichler ◽  
F. Hofer
Keyword(s):  
Electron Microscopy ◽  
Cross Sections ◽  
Protective Coatings ◽  
Multilayer Coating ◽  
Chemical Vapour ◽  
Chemical Properties ◽  
Ceramic Coatings ◽  
Hard Metal ◽  
Deposition Parameters ◽  
Transmission Electron

To improve their working life, hard metal tools are coated with ceramic protective coatings by means of chemical vapour deposition (CVD). Generally, several layers are deposited, e.g. titaniumcarbide, titaniumnitride, titaniumcarbonitride and aluminiumoxide with thicknesses ranging from some 10 nm to some μm.The understanding of mechanical properties of the coatings is dependent on gaining a knowledge of both the interfaces and the structure of the coatings involved. The coating properties are, in turn, dependent on the coating deposition parameters. A detailed understanding of the influence of these parameters on the mechanical and chemical properties of the multilayer/substrate combination is therefore required.The structure and morphology of the multilayer coatings have been already investigated by using optical and scanning electron microscopy (SEM), whereas transmission electron microscopy (TEM) was hitherto only applied to the study of single TiC or Al2O3 coatings.For TEM-investigations cross-sections must be taken through the multilayer coating and the cemented carbide substrate. In our investigations, a method of preparation described by Newcomb et al.

scholarly journals The Wear Mechanisms Description Of Multilayer Coatings, Performed By Transmission Electron Microscopy – An Overview Of The Own Research Work

2015 ◽  
Vol 60 (3) ◽  
pp. 2319-2326
Author(s):  
Ł. Major
Keyword(s):  
Wear Mechanisms ◽  
Research Work ◽  
Life Time ◽  
Mechanical Tests ◽  
Multilayer Coatings ◽  
Small Length Scale ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Layer Coating ◽  
Ball On Disc

Abstract The aim of the presented paper was to describe the wear mechanisms operating at the small length scale in multilayer coatings subjected to a mechanical testing. A hybrid PLD system (Pulsed Laser Deposition connected with magnetron sputtering) was used for the multi-layer coating deposition. Coatings were subjected to indentation, ball-on disc wear and scratch adhesion tests. Microstructure of the as-deposited coating and after mechanical tests was studied using the Scanning (SEM) and the Transmission (TEM) Electron Microscopes. The research work revealed that application of innovative multilayer coatings may allow to predict their life time and to steer their properties.

Ultrastructural Analysis of the Salivary Glands of Gromphadorhina Portentosa (Schaum)

1977 ◽  
Vol 35 ◽  
pp. 638-639
Author(s):  
P.J. Dailey
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Salivary Glands ◽  
Secretory Vesicles ◽  
The Past ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
Gromphadorhina Portentosa ◽  
Scanning Electron ◽  
Topographical Relief

The structure of insect salivary glands has been extensively investigated during the past decade; however, none have attempted scanning electron microscopy (SEM) in ultrastructural examinations of these secretory organs. This study correlates fine structure by means of SEM cryofractography with that of thin-sectioned epoxy embedded material observed by means of transmission electron microscopy (TEM).Salivary glands of Gromphadorhina portentosa were excised and immediately submerged in cold (4°C) paraformaldehyde-glutaraldehyde fixative1 for 2 hr, washed and post-fixed in 1 per cent 0s04 in phosphosphate buffer (4°C for 2 hr). After ethanolic dehydration half of the samples were embedded in Epon 812 for TEM and half cryofractured and subsequently critical point dried for SEM. Dried specimens were mounted on aluminum stubs and coated with approximately 150 Å of gold in a cold sputtering apparatus.Figure 1 shows a cryofractured plane through a salivary acinus revealing topographical relief of secretory vesicles.

An Electron Microscope Study of Interdiffusion and Compound Formation in Ta-Au Thin Films

1973 ◽  
Vol 31 ◽  
pp. 32-33 ◽  
Author(s):  
T. C. Tisone ◽  
S. Lau
Keyword(s):  
Electron Microscope ◽  
Electron Microscope Study ◽  
Thermally Grown Oxide ◽  
Ion Milling ◽  
Compound Formation ◽  
Technology Application ◽  
Transmission Electron ◽  
Before And After ◽  
Au Thin Films

In a study of the properties of a Ta-Au metallization system for thin film technology application, the interdiffusion between Ta(bcc)-Au, βTa-Au and Ta2M-Au films was studied. Considered here is a discussion of the use of the transmission electron microscope(TEM) in the identification of phases formed and characterization of the film microstructures before and after annealing.The films were deposited by sputtering onto silicon wafers with 5000 Å of thermally grown oxide. The film thicknesses were 2000 Å of Ta and 2000 Å of Au. Samples for TEM observation were prepared by ultrasonically cutting 3mm disks from the wafers. The disks were first chemically etched from the silicon side using a HNO3 :HF(19:5) solution followed by ion milling to perforation of the Au side.

Ultrastructural investigation of an adenoma of the pituitary post mortem

1987 ◽  
Vol 45 ◽  
pp. 622-623
Author(s):  
Shirley Siew ◽  
W. C. deMendonca
Keyword(s):  
Deleterious Effect ◽  
Anterior Lobe ◽  
Definitive Diagnosis ◽  
Pars Intermedia ◽  
Post Mortem ◽  
Close Apposition ◽  
Autopsy Material ◽  
Progressive Loss ◽  
Transmission Electron ◽  
Means Of Transmission

The deleterious effect of post mortem degeneration results in a progressive loss of ultrastructural detail. This had led to reluctance (if not refusal) to examine autopsy material by means of transmission electron microscopy. Nevertheless, Johannesen has drawn attention to the fact that a sufficient amount of significant features may be preserved in order to enable the establishment of a definitive diagnosis, even on “graveyard” tissue.Routine histopathology of the autopsy organs of a woman of 78 showed the presence of a well circumscribed adenoma in the anterior lobe of the pituitary. The lesion came into close apposition to the pars intermedia. Its architecture was more compact and less vascular than that of the anterior lobe. However, there was some grouping of the cells in relation to blood vessels. The cells tended to be smaller, with a higher nucleocytoplasmic ratio. The cytoplasm showed a paucity of granules. In some of the cells, it was eosinophilic.

Effect of MWCNT doping on the structural and optical properties of PVC/PVDF polymer blend

2017 ◽  
Vol 13 (2) ◽  
pp. 4640-4647
Author(s):  
A. M. Abdelghany ◽  
M.S. Meikhail ◽  
S.I. Badr ◽  
A. S. Momen
Keyword(s):  
Surface Damage ◽  
X Ray Diffraction ◽  
Dopant Content ◽  
Casting Technique ◽  
Transmission Electron ◽  
Dopant Level ◽  
Before And After ◽  
Carbon Nano Tubes ◽  
Small Band ◽  
Vibrational Bands

Thin film samples of pristine polyvinyl chloride (PVC), poly vinyldine fluoride (PVDF) in combination with their blend in addition to samples containing factorial mass fraction of multi wall carbon nano-tubes (MWCNTs) in the dopant level were prepared via routine casting technique using tetrahydrofurane (THF) as a common solvent. X-ray diffraction and transmission electron microscopy (TEM) depict the nano-scale (15-25 nm) of functionalized MWCNTs with no surface damage results from functionalization process.X-ray diffraction (XRD) shows a semi-crystalline nature of PVDF with evidence for more than one phase namely a and b phases. The fraction of b phase was calculated and correlated to the dopant content. FTIR optical absorption spectra revels a preservation of the main vibrational bands before and after addition of MWCNTs in the doping level with a presence of new small band 1151 cm-1 assigned for the interaction and complexation between constituents.

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