scholarly journals Nanotribological response of a-C:H coated metallic biomaterials: the cases of stainless steel, titanium, and niobium

2018 ◽  
Vol 16 (4) ◽  
pp. 230-240
Author(s):  
Konstantinos Kapnisis ◽  
Marios Constantinou ◽  
Maria Kyrkou ◽  
Petros Nikolaou ◽  
Andreas Anayiotos ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Chemical Vapor ◽  
Scratch Resistance ◽  
Force Microscopy ◽  
Metallic Biomaterials ◽  
Atomic Force ◽  
Wear And Corrosion ◽  
Metal Plates ◽  
Before And After ◽  
Tribomechanical Characteristics

Background Wear and corrosion have been identified as two of the major forms of medical implant failures. This study aims to improve the surface, protective and tribological characteristics of bare metals used for medical implants, so as to improve scratch resistance and increase lifetime. Methods Hydrogenated amorphous carbon (a-C:H) films were deposited, using plasma enhanced chemical vapor deposition (PECVD), on stainless steel (SS), titanium (Ti) and niobium (Nb) metal plates. Nanomechanical and nanotribological responses were investigated before and after a-C:H deposition. Film thickness and density were quantified through X-ray reflectivity, and surface morphology before and after deposition were measured using atomic force microscopy, whereas the tribomechanical characteristics were probed using instrumented indentation. Results and conclusions Films of approximately 40 nm in thickness and density of 1.7 g/cm3 were deposited. The a-C:H films reduce the roughness and coefficient of friction while improving the tribomechanical response compared with bare metals for Ti, SS and Nb plates. The very good tribomechanical properties of a-C:H make it a promising candidate material for protective coating on metallic implants.

The Effects of Friction and Wear on PECVD Diamond Films.

1994 ◽  
Vol 339 ◽  
Author(s):  
M. L. Languell ◽  
J. L. Davidson ◽  
J. J. Wert ◽  
M. A. George ◽  
W. E. Collins ◽  
...  
Keyword(s):  
Vapor Deposition ◽  
Friction And Wear ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Nasa Lewis Research ◽  
Force Microscopy ◽  
Atomic Force ◽  
Mean Diameter ◽  
Before And After ◽  
Surface Changes

ABSTRACTThe effects of friction and wear were examined on plasma enhanced chemical vapor deposition (PECVD) diamond films deposited on tungsten substrates. The tribology of diamond on diamond was studied and the changes in surface roughness and the bearing ratio were determined before and after wear. The (111) textured heteroepitaxial films were studied morphologically by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The changes in morphology involved a transition from the large as grown diamond crystallites with a mean diameter of 10 μm to a surface with grains as small as 100 nm. The nature of the wear-modified films will be discussed regarding the possible mechanisms for the surface changes.Work partially supported by NASA Lewis Research Center grant NAG3–1430.

Effect of Electron Beam Bombarding of the Catalyst Layer on the Growth of Carbon Nanostructures by TCVD Method

2011 ◽  
Vol 264-265 ◽  
pp. 1324-1328
Author(s):  
A. Mahmoodi ◽  
M. Ghoranneviss ◽  
D. Hanifeh ◽  
K. Mehrani ◽  
M. Rahbar Zareh
Keyword(s):  
Carbon Nanotubes ◽  
Electron Beam ◽  
Carbon Nanostructures ◽  
Chemical Vapor ◽  
Catalyst Layer ◽  
Sio2 Substrate ◽  
Force Microscopy ◽  
Fe Catalyst ◽  
Atomic Force ◽  
Before And After

The growth behavior of carbon nanotubes (CNTs) grown on electron bombarded catalyst layer has been investigated in this paper. A hot cathodic electron beam facility was employed to electron bombarding of catalyst layer before stage of CNTs growth. The growth of carbon nanotubes was performed on the Fe catalyst layer with sio2 substrate in an environment of different mixed gases (H2, NH3 and C2H2) by Thermal Chemical Vapor Deposition (TCVD) system. The pretreated substrates were probed by Atomic Force Microscopy (AFM) and CNTs grown was confirmed by Raman spectroscopy. Moreover, all samples were analyzed by Scanning Electron Microscopy (SEM) before and after growth of CNTs. SEM analyzes clarified that the catalyst grains has been smaller under effect of electron beam bombardment.

Characterization of the Interface Between Metal Contacts and Epilayers of Doped Silicon Carbide

1995 ◽  
Vol 405 ◽  
Author(s):  
M. A. George ◽  
D. J. Larkin ◽  
J. Petit ◽  
A. Burger ◽  
S. H. Morgan ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Ohmic Contacts ◽  
Chemical Vapor ◽  
Metal Contacts ◽  
Aluminum Films ◽  
Force Microscopy ◽  
Atomic Force ◽  
Chemical Vapor Deposited ◽  
Before And After ◽  
P Type

AbstractAluminum contacts on chemical vapor deposited (CVD) SiC films were studied to examine variations in the chemical, morphological and electrical properties of the samples. Nitrogen and aluminum doped substrates were prepared to give n-type and p-type SiC epilayers respectively. These preparations were examined by surface sensitive spectroscopies and by atomic force microscopy (AFM). Samples were studied both before and after the deposition of aluminum films to compare differences between SiC(p++)/metal and SiC(n++)/metal contact interfacial properties. Aluminum has generally been found to have good adherence to the n+ epilayer but do not form good ohmic contacts, while metal films deposited on p+ epilayers have had poor adherence but have been found to provide better ohmic character. AFM images revealed nanometer sized clusters, attributed to excess Si on the n+ epilayers, while no clusters were observed on the p+ epilayers. XPS studies of the as-prepared samples indicated that the n+ epilayers had higher concentrations of oxides which may enhance adhesion. The chemical composition and morphology is discussed and correlated to the electrical properties obtained for the various samples.

scholarly journals Effect of 0.05% Sodium Fluoride Mouthwash on Surface Roughness and Friction Between Ceramic Brackets and Rhodium-Coated and Uncoated Stainless Steel Wires

2019 ◽  
Author(s):  
Tahereh HosseinzadehNik ◽  
Hannaneh Ghadirian ◽  
Tabassom Hooshmand ◽  
Mohammad Javad Kharrazi fard ◽  
Maryam Nasiri ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Sodium Fluoride ◽  
Artificial Saliva ◽  
Testing Machine ◽  
Significance Level ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After ◽  
Ceramic Brackets

Objectives: This study aimed to assess the effect of 0.05% sodium fluoride (NaF) mouthwash on the surface roughness and friction between ceramic brackets and rhodium-coated (RC) and uncoated stainless steel (SS) wires. Materials and Methods: This experimental study was performed on 48 maxillary premolar ceramic brackets. Twenty-four pieces of RC-SS wires were used. Samples were divided into four groups. Groups 1 and 2 were immersed in artificial saliva, and groups 3 and 4 were immersed in a solution consisting of artificial saliva (9%) and mouthwash (91%). To assess surface roughness, images were obtained from the surface of wires and brackets with atomic force microscopy (AFM) and scanning electron microscopy (SEM) before and after the intervention. To assess friction, the wires were ligated into brackets, and friction was measured at a crosshead speed of 0.5 mm/minute using a universal testing machine. Data were analyzed using one-way analysis of variance (ANOVA) at the 0.05 significance level. Results: Friction during sliding in RC wires was significantly less than that in SS wires (P<0.05). Increase in the friction in SS wires by mouthwash was significantly greater compared to RC wires (P<0.05). Surface roughness coefficients of the wires before the intervention were not significantly different. The surface roughness of the wires significantly increased after the intervention and it was greater in SS wires than in RC wires (P<0.05). Conclusion: Considering the lower friction and surface roughness of SS-RC wires compared to SS wires, SS-RC wires may be a better alternative for use with ceramic brackets.

Stability of AZO Thin Films under the Environment of Hydrogen Plasma

2011 ◽  
Vol 194-196 ◽  
pp. 2334-2339
Author(s):  
Qing Nan Zhao ◽  
Wen Hui Yuan ◽  
Hong Yu Liang ◽  
Wei Yuan Wang ◽  
Pu Lei Yang ◽  
...  
Keyword(s):  
Thin Films ◽  
Treatment Time ◽  
Hydrogen Plasma ◽  
Chemical Vapor ◽  
Force Microscopy ◽  
Glass Substrates ◽  
Atomic Force ◽  
Before And After ◽  
Aluminum Doped Zinc Oxide ◽  
Hall Effect Measurements

The textured thin films of Aluminum-doped zinc oxide (AZO), prepared on glass substrates by magnetron sputtering, were treated under the environment of hydrogen plasma in plasma enhanced chemical vapor deposition (PECVD) chamber for different time. The structure and properties of the thin films before and after the treatment were characterized by X-ray diffraction (XRD), Atomic Force Microscopy (AFM), field-emission scanning electron microscope (FESEM), Hall effect measurements and UV-Vis –NIR spectrometer. The results obtained showed that, after the treatment, the crystal structure of the films was not obviously changed, the roughness of the films was reduced, the carrier concentration and Hall mobility of the films increased to a certain saturated level with the treatment time, and the conductivity of the films increased. The transmittance and optical band gap of the AZO films was not affected by plasma treatment.

Elucidation of the growth mechanism of MoS2 during the CVD process

MRS Advances ◽  
2018 ◽  
Vol 4 (10) ◽  
pp. 581-586 ◽  
Author(s):  
Sajeevi S Withanage ◽  
Mike Lopez ◽  
Wasee Sameen ◽  
Vanessa Charles ◽  
Saiful I Khondaker
Keyword(s):  
Molybdenum Trioxide ◽  
Chemical Vapor ◽  
Second Step ◽  
Force Microscopy ◽  
Atomic Force ◽  
Lack Of Control ◽  
Before And After ◽  
Cvd Growth ◽  
Microscopy Characterization ◽  
Atomic Force Microscopy Characterization

ABSTRACTChemical vapor deposition (CVD) growth of two-dimensional molybdenum disulfide (MoS2) using molybdenum trioxide (MoO3) and sulfur (S) powder often results in intermediate molybdenum oxy-sulfide (MoOS2) species along with MoS2 due to a lack of control over the vapor pressure required for the clean growth. Much effort has been devoted in understanding and controlling of these intermediate MoOS2 specifies. Here, we show that with a second step sulfurization at moderate temperatures, these MoOS2 crystals can be transformed to monolayer MoS2 crystals. Scanning electron microscopy, Raman and photoluminescence spectroscopy and atomic force microscopy characterization carried out before and after re-sulfurization confirm the monolayer MoS2 growth via this route. This study shows that MoOS2 formed at the intermediate state can be successfully recycled to MoS2.

Surface roughness measurements of vanadium-contaminated fluidized cracking catalysts by atomic force microscopy

1996 ◽  
Vol 54 ◽  
pp. 866-867
Author(s):  
H. Kinney ◽  
M.L. Occelli ◽  
S.A.C. Gould
Keyword(s):  
Surface Roughness ◽  
Zeolite Y ◽  
Atomic Level ◽  
Microporous Structure ◽  
Contact Mode ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After ◽  
Roughness Measurements ◽  
Cracking Catalysts

For this study we have used a contact mode atomic force microscope (AFM) to study to topography of fluidized cracking catalysts (FCC), before and after contamination with 5% vanadium. We selected the AFM because of its ability to well characterize the surface roughness of materials down to the atomic level. It is believed that the cracking in the FCCs occurs mainly on the catalysts top 10-15 μm suggesting that the surface corrugation could play a key role in the FCCs microactivity properties. To test this hypothesis, we chose vanadium as a contaminate because this metal is capable of irreversibly destroying the FCC crystallinity as well as it microporous structure. In addition, we wanted to examine the extent to which steaming affects the vanadium contaminated FCC. Using the AFM, we measured the surface roughness of FCCs, before and after contamination and after steaming.We obtained our FCC (GRZ-1) from Davison. The FCC is generated so that it contains and estimated 35% rare earth exchaged zeolite Y, 50% kaolin and 15% binder.

Improving Tribological Characteristics of Hip Prostheses Using Biocompatible Nanocoatings

2013 ◽  
Vol 741 ◽  
pp. 67-72 ◽  
Author(s):  
Gheorghe I. Gheorghe ◽  
Liliana Laura Badita
Keyword(s):  
Hip Prosthesis ◽  
Protective Coatings ◽  
Scratch Resistance ◽  
Hip Prostheses ◽  
Force Microscopy ◽  
Tin Coatings ◽  
Femoral Heads ◽  
Before And After ◽  
Tin Thin Films ◽  
Steel Substrates

Total hip prosthesis (THP) is the most success of the 20th century in orthopaedic biomedical engineering. However due to difficult conditions within the human body its durability is generally limited to 15-16 years. THP is a bio-tribosystem, on which many mechanical, thermal, chemical and biological factors act. This paper presents the results of an analysis regarding the topography and tribological parameters of femoral heads structures before and after TiN coating. We report on the synthesis of TiN thin films on steel substrates by pulsed laser deposition (PLD) method for improving the mechanical characteristics of the structures. Adhesion resistance of the coating on the sub-layer was evaluated by scratching tests accompanied by Optical Microscopy (OM), Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). As a principal result, this work points out that TiN protective coatings deposited by PLD technique with the maximum number of pulses can represent an alternative technology to ensure adhesion and scratch resistance of TiN coatings on femoral heads.

Micromechanisms of Hydrogen-Assisted Cracking in Super Duplex Stainless Steel Investigated by Scanning Probe Microscopy

2014 ◽  
Author(s):  
Bai An ◽  
Takashi Iijima ◽  
Chris San Marchi ◽  
Brian Somerday
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Scanning Tunneling ◽  
Super Duplex Stainless Steel ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
Atomic Force ◽  
Hydrogen Assisted Cracking ◽  
Cracking Mechanisms ◽  
Localized Plastic Deformation

Understanding the micromechanisms of hydrogen-assisted fracture in multiphase metals is of great scientific and engineering importance. By using a combination of scanning electron microscopy (SEM), scanning tunneling microscopy (STM), atomic force microscopy (AFM) and magnetic force microscopy (MFM), the micromorphology of fracture surface and microcrack formation in hydrogen-precharged super duplex stainless steel 2507 are characterized from microscale to nanoscale. The results reveal that the fracture surfaces consist of quasi-brittle facets with riverlike patterns at the microscale, which exhibit rough irregular patterns or remarkable quasi-periodic corrugation patterns at the nanoscale that can be correlated with highly localized plastic deformation. The microcracks preferentially initiate and propagate in ferrite phase and are stopped or deflected by the boundaries of the austenite phase. The hydrogen-assisted cracking mechanisms in super duplex stainless steel are discussed according to the experimental results and hydrogen-enhanced localized plasticity theory.

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