scholarly journals Improvement of CoCr Alloy Characteristics by Ti-Based Carbonitride Coatings Used in Orthopedic Applications

Coatings ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 495
Author(s):  
Mihaela Dinu ◽  
Iulian Pana ◽  
Petronela Scripca ◽  
Ioan Gabriel Sandu ◽  
Catalin Vitelaru ◽  
...  
Keyword(s):  
Crystallite Size ◽  
Layer Structure ◽  
Corrosion Current ◽  
Face Centered Cubic ◽  
Corrosive Environment ◽  
Load Bearing ◽  
Cathodic Arc Deposition ◽  
Ticn Coating ◽  
Face Centered

The response of the human body to implanted biomaterials involves several complex reactions. The potential success of implantation depends on the knowledge of the interaction between the biomaterials and the corrosive environment prior to the implantation. Thus, in the present study, the in vitro corrosion behavior of biocompatible carbonitride-based coatings are discussed, based on microstructure, mechanical properties, roughness and morphology. TiCN and TiSiCN coatings were prepared by the cathodic arc deposition method and were analyzed as a possible solution for load bearing implants. It was found that both coatings have an almost stoichiometric structure, being solid solutions, which consist of a mixture of TiC and TiN, with a face-centered cubic (FCC) structure. The crystallite size decreased with the addition of Si into the TiCN matrix: the crystallite size of TiCN was 16.4 nm, while TiSiCN was 14.6 nm. The addition of Si into TiCN resulted in smaller Ra roughness values, indicating a beneficial effect of Si. All investigated surfaces have positive skewness, being adequate for the load bearing implants, which work in a corrosive environment. The hardness of the TiCN coating was 36.6 ± 2.9 GPa and was significantly increased to 47.4 ± 1 GPa when small amounts of Si were added into the TiCN layer structure. A sharp increase in resistance to plastic deformation (H3/E2 ratio) from 0.63 to 1.1 was found after the addition of Si into the TiCN matrix. The most electropositive value of corrosion potential was found for the TiSiCN coating (−14 mV), as well as the smallest value of corrosion current density (49.6 nA cm2), indicating good corrosion resistance in 90% DMEM + 10% FBS, at 37 ± 0.5 °C.

scholarly journals Characterization of Cobalt Sulfide Thin Films Synthesized from Acidic Chemical Baths

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Tizazu Abza ◽  
Dereje Gelanu Dadi ◽  
Fekadu Gashaw Hone ◽  
Tesfaye Chebelew Meharu ◽  
Gebremeskel Tekle ◽  
...  
Keyword(s):  
Thin Films ◽  
Crystallite Size ◽  
Deposition Time ◽  
Average Crystallite Size ◽  
Cobalt Sulfide ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
Face Centered

Cobalt sulfide thin films were synthesized from acidic chemical baths by varying the deposition time. The powder X-ray diffraction studies indicated that there are hexagonal CoS, face-centered cubic Co3S4, and cubic Co9S8 phases of cobalt sulfide. The crystallite size of the hexagonal CoS phase decreased from 52.8 nm to 22.5 nm and that of the cubic Co9S8 phase increased from 11 nm to 60 nm as the deposition time increased from 2 hrs to 3.5 hrs. The scanning electron microscopic images revealed crack and pinhole free thin films with uniform and smooth background and few large polygonal grains on the surface. The band gap of the cobalt sulfide thin films decreased from 1.75 eV to 1.3 eV as the deposition time increased from 2 hrs to 3.5 hrs. The photoluminescence (PL) spectra of the films confirmed the emission of ultraviolet, violet, and blue lights. The intense PL emission of violet light at 384 nm had red shifted with increasing deposition time that could be resulted from the increase in the average crystallite size. The FTIR spectra of the films indicated the presence of OH, C-O-H, C-O, double sulfide, and Co-S groups. As the deposition time increased, the electrical resistivity of the cobalt sulfide thin films decreased due to the increase in both the crystallite size and the films’ thickness.

Synthesis and Characterization of Nickel-Iron-Silicon Nitride Nanocomposite

2010 ◽  
Vol 97-101 ◽  
pp. 1360-1363 ◽  
Author(s):  
Yusrini Marita ◽  
Iskandar Idris Yaacob
Keyword(s):  
Thin Films ◽  
Silicon Nitride ◽  
Crystallite Size ◽  
Iron Film ◽  
Face Centered Cubic ◽  
Mapping Procedure ◽  
Nickel Iron ◽  
Iron Silicon ◽  
Nanocomposite Thin Films ◽  
Face Centered

Nickel-iron-silicon nitride nanocomposite thin films were prepared by electrodeposition technique. The deposition was performed at current density of 11.5 A dm-2. Nano-size silicon nitride was mixed in the electrolyte bath as dispersed phase. The effects of silicon nitride nanoparticulates in the nickel-iron nanocomposite thin films were investigated in relation to the amount of silicon nitride in the plating bath. X-ray diffraction (XRD) analysis showed that the deposited nickel iron film has face-centered cubic structure (FCC). However, a mixture of body-centered cubic (BCC) and face-centered cubic (FCC) phases were observed for nickel iron-silicon nitride nanocomposite films. The crystallite size of Ni-Fe nanocomposite coating decreased with increasing amount of silicon nitride in the film. From elemental mapping procedure, Si3N4 nanopaticles were uniformly distributed in the Ni-Fe film. The presence of silicon nitride increased the hardness of the film. The microhardness of the nickel-iron nanocomposite increased from 495 HV for nickel-iron film to 846 HV for nickel-iron nanocomposite film with 2 at. % Si. The coercivity of Ni-Fe nanaocomposite films increases with decreasing crystallite size.

Face-centered-cubic to Hexagonal-close-packed Transformation in Nanocrystalline Ni(Si) by Mechanical Alloying

2000 ◽  
Vol 15 (7) ◽  
pp. 1429-1432 ◽  
Author(s):  
M. K. Datta ◽  
S. K. Pabi ◽  
B. S. Murty
Keyword(s):  
Solid Solution ◽  
Equation Of State ◽  
Shear Modulus ◽  
Mechanical Alloying ◽  
Crystallite Size ◽  
Negative Pressure ◽  
Volume Expansion ◽  
Face Centered Cubic ◽  
Hexagonal Close Packed ◽  
Face Centered

An allotropic transition from face-centered-cubic (fcc) to hexagonal-close-packed (hcp) Ni(Si) solid solution in Ni95Si5 and Ni90Si10 during nanocrystallization by mechanical alloying is reported. The transformation was identified as a defect-induced melting accompanied by a volume expansion of 8.6% and was observed when fcc Ni(Si) reached a critical crystallite size of 10 nm. Calculation based on equation of state showed that a 37% reduction in tetragonal shear modulus and a negative pressure of about 8.7 GPa were generated at the onset of transformation.

Si Doped and Un-Doped CrN Thin Films Produced by Magnetron Sputtering: Structural and Mechanical Properties

2012 ◽  
Vol 18-19 ◽  
pp. 201-211 ◽  
Author(s):  
L. Cunha ◽  
C. Moura
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Magnetron Sputtering ◽  
Crystallite Size ◽  
Processing Parameters ◽  
Preferred Orientation ◽  
Chromium Nitride ◽  
Face Centered Cubic ◽  
Face Centered ◽  
Silicon Doped

Chromium nitride and silicon doped chromium nitride thin films have been deposited by r.f. reactive magnetron sputtering. The effect of processing parameters on the properties of chromium nitride films and the correspondent influence of the addition of silicon on the chromium nitride matrix in the films structure and mechanical properties have been investigated. The characterization of the coatings was performed by X-ray diffraction (XRD), and nano-indentation experiments. These studies allow analyzing the crystalline phases, crystal orientation/texture, crystallite size, mechanical properties and the relations between the characteristics of the films. The increase of the nitrogen partial pressure in the working atmosphere produces changes from a body-centered cubic (bcc) Cr structure, to hexagonal Cr2N to face-centered cubic (fcc) CrN structure, with CrN (111) preferred orientation. For the films with a dominant Cr2N phase the hardness has a relative maximum (42 GPa). The highest hardness was measured for a coating with dominant CrN phase (45 GPa) with a crystallite size around 18 nm. The addition of Si, in the films with CrN dominant phase, maintains the CrN (111) preferred orientation and produced variable changes in films hardness, depending on deposition conditions.

scholarly journals Structural building principles of complex face-centered cubic intermetallics

2011 ◽  
Vol 67 (4) ◽  
pp. 269-292 ◽  
Author(s):  
Julia Dshemuchadse ◽  
Daniel Y. Jung ◽  
Walter Steurer
Keyword(s):  
Chemical Composition ◽  
Crystal Structures ◽  
Electronic Band Structure ◽  
Layer Structure ◽  
Repeat Unit ◽  
Basic Structure ◽  
Group Symmetry ◽  
Face Centered Cubic ◽  
Electronic Band ◽  
Face Centered

Fundamental structural building principles are discussed for all 56 known intermetallic phases with approximately 400 or more atoms per unit cell and space-group symmetry F\bar{4}3m, Fd\bar{3}m, Fd\bar{3}, Fm\bar{3}m or Fm\bar{3}c. Despite fundamental differences in chemical composition, bonding and electronic band structure, their complex crystal structures show striking similarities indicating common building principles. We demonstrate that the structure-determining elements are flat and puckered atomic {110} layers stacked with periodicities 2p. The atoms on this set of layers, which intersect each other, form pentagon face-sharing endohedral fullerene-like clusters arranged in a face-centered cubic packing (f.c.c.). Due to their topological layer structure, all these crystal structures can be described as (p × p × p) = p 3-fold superstructures of a common basic structure of the double-diamond type. The parameter p, with p = 3, 4, 7 or 11, is determined by the number of layers per repeat unit and the type of cluster packing, which in turn are controlled by chemical composition.

Biosynthesizing Gold Nanoparticles with Parkia biglobosa Leaf Extract for Antibacterial Efficacy In Vitro and Photocatalytic Degradation Activities of Rhodamine B Dye

2020 ◽  
Vol 12 (7) ◽  
pp. 970-981
Author(s):  
Davids Joan Shine ◽  
Sun Shasha ◽  
Alorku Kingdom ◽  
Okoampah Emmanuel ◽  
Sandra Senyo Fometu ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Rhodamine B ◽  
Average Crystallite Size ◽  
Direct Analysis ◽  
Face Centered Cubic ◽  
Parkia Biglobosa ◽  
X Ray ◽  
Synthesis Of Nanoparticles ◽  
Face Centered

The toxicity and cost involved in the synthesis of nanoparticles using physical and chemical methods have led to the emergence of biological techniques being employed by scientists. Hence the present study employed an eco-friendly method by using Parkia biglobosa leaves extract as a reducing and stabilizing agent of chloroauric gold (HAuCl4) to gold nanoparticle (AuNPs). Direct Analysis in Real-Time (DART-MS) was employed for phytochemical screening. However, the AuNPs were characterized by Ultraviolet-Visible spectroscopy (UV/Vis), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray spectroscopy, Fourier Transmission Infrared Spectroscopy, and X-ray diffraction spectroscopy, before the antibacterial and photocatalysis study. DART-MS showed more than 20 phytochemicals, including phenolic compounds. The FT-IR revealed the existence of flavonoids that we hypothesized are responsible for gold chloride reduction reactions. The optical properties of the gold nanoparticles by UV/Vis spectra registered plasmon surface resonance at a peak of 530 nm, whiles TEM revealed the AuNPs to be mono-dispersed and shapes were spherical and triangular with sizes ranging from 3.4 nm to 39.7 nm. XRD also recorded face-centered cubic AuNPs with 20.94 nm as the average crystallite size. The synthesized AuNPs were able to elucidate their anti-bacterial efficacy on Gram-positive bacteria Staphylococcus aureus, enterococcus faecalis and Gram-negative bacteria Escherichia coli, pseudomonas aeruginosa. The photocatalytic activities of AuNPs under UV/Vis irradiation exhibited a substantial degradation effect on rhodamine b (RhB) within 75 minutes. Due to their non-toxic nature, plant-mediated biosynthesized AuNPs, would be valuable in enhancing their biomedical applications and in wastewater treatment.

Voids in Irradiated Tungsten and Molybdenum

1969 ◽  
Vol 27 ◽  
pp. 190-191
Author(s):  
Robert C. Rau ◽  
Robert L. Ladd
Keyword(s):  
Melting Point ◽  
Fast Neutron ◽  
Neutron Irradiation ◽  
Elevated Temperatures ◽  
Irradiation Temperature ◽  
The Body ◽  
Face Centered Cubic ◽  
Body Centered Cubic ◽  
Cubic Metals ◽  
Face Centered

Recent studies have shown the presence of voids in several face-centered cubic metals after neutron irradiation at elevated temperatures. These voids were found when the irradiation temperature was above 0.3 Tm where Tm is the absolute melting point, and were ascribed to the agglomeration of lattice vacancies resulting from fast neutron generated displacement cascades. The present paper reports the existence of similar voids in the body-centered cubic metals tungsten and molybdenum.

A study of interface sliding at F.C.C.-B.C.C. boundaries in a Cu-Zn alloy

1978 ◽  
Vol 36 (1) ◽  
pp. 422-423
Author(s):  
F. Monchoux ◽  
A. Rocher ◽  
J.L. Martin
Keyword(s):  
Face Centered Cubic ◽  
Creep Tests ◽  
High Voltage Electron Microscopy ◽  
Diffusion Treatment ◽  
Voltage Electron ◽  
The Face ◽  
Face Centered ◽  
Interface Sliding ◽  
Zn Alloy ◽  
Made In

Interphase sliding is an important phenomenon of high temperature plasticity. In order to study the microstructural changes associated with it, as well as its influence on the strain rate dependence on stress and temperature, plane boundaries were obtained by welding together two polycrystals of Cu-Zn alloys having the face centered cubic and body centered cubic structures respectively following the procedure described in (1). These specimens were then deformed in shear along the interface on a creep machine (2) at the same temperature as that of the diffusion treatment so as to avoid any precipitation. The present paper reports observations by conventional and high voltage electron microscopy of the microstructure of both phases, in the vicinity of the phase boundary, after different creep tests corresponding to various deformation conditions.Foils were cut by spark machining out of the bulk samples, 0.2 mm thick. They were then electropolished down to 0.1 mm, after which a hole with thin edges was made in an area including the boundary

Microstructure of Electro-Eroded Cemented Carbide Surfaces

1968 ◽  
Vol 26 ◽  
pp. 284-285
Author(s):  
V. N. Filimonenko ◽  
M. H. Richman ◽  
J. Gurland
Keyword(s):  
Surface Layer ◽  
Cobalt Content ◽  
Cemented Carbides ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Metallographic Examination ◽  
Standard Procedures ◽  
Face Centered ◽  
Diamond Paste ◽  
Plastic Carbon

The high temperatures and pressures that are found in a spark gap during electrical discharging lead to a sharp phase transition and structural transformation in the surface layer of cemented carbides containing WC and cobalt. By means of X-ray diffraction both W2C and a high-temperature monocarbide of tungsten (face-centered cubic) were detected after electro-erosion. The W2C forms as a result of the peritectic reaction, WC → W2C+C. The existence and amount of the phases depend on both the energy of the electro-spark discharge and the cobalt content. In the case of a low-energy discharge (i.e. C=0.01μF, V = 300v), WC(f.c.c.) is generally formed in the surface layer. However, at high energies, (e.g. C=30μF, V = 300v), W2C is formed at the surface in preference to the monocarbide. The phase transformations in the surface layer are retarded by the presence of larger percentages of cobalt.Metallographic examination of the electro-eroded surfaces of cemented carbides was carried out on samples with 5-30% cobalt content. The specimens were first metallographically polished using diamond paste and standard procedures and then subjected to various electrical discharges on a Servomet spark machining device. The samples were then repolished and etched in a 3% NH4OH electrolyte at -0.5 amp/cm2. Two stage plastic-carbon replicas were then made and shadowed with chromium at 27°.

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