Surface Of Metallic Materials Research Articles

Multiscaling of lattice curvature on friction surfaces of metallic materials as a basis of their wear mechanism

A comprehensive structural study has been performed to explore deformation and wear debris formation on friction surfaces of metallic materials. A hierarchy of structural scales of plastic deformation and failure during wear has been established. The nanoscale plays the major role in the hierarchical self-organization of multiscale debris formation processes. On this scale, bifurcational interstitial states arise in zones of local lattice curvature, with plastic distortion and motion of nonequilibrium point defects which determine the nonlinear dynamics of structure formation and wear of surface layers. Nonequilibrium vacancies on lattice sites form microporosity through the coalescence mechanism under plastic distortion. The microporosity is a precursor of meso- and macroscale plastic shearing that defines wear debris formation.

Inverse estimation of the material parameters at metal surface irradiated by laser pulse

Based on nonlinear conjugate gradient theory, a new inversion algorithm is proposed to estimate the reflection and absorption coefficients for the surface of metallic materials irradiated by pulsed laser. Firstly, the basic principle of direct and inverse problems of laser heating is showed, and analytical expression of sensitivity coefficient is obtained due to the analytical solution of direct problem. Then, the sensitivity analysis is carried out, and the change of the relative sensitivity coefficient is investigated. The algorithm is verified by the specific example, and the best condition of the convergence is analyzed. Finally, the influence of the iterative initial values on the convergence of the iterative process and the variation characteristics of the inversion results in the iterative process are investigated with the special model. Research results can be used for analysis of material properties and selection of parameters in the field of laser processing, and also can provide an effective means for the evaluation of the effect of laser damage, it has important theoretical and practical significance.

Anodization of Ti-based materials for biomedical applications: A review

Commercially pure titanium (cpTi) and titanium alloys are the most commonly used metallic biomaterials. Biomedical requirements for the successful usage of metallic implant materials include their high mechanical strength, low elastic modulus, excellent biocompatibility and high corrosion resistance. It is evident that the response of a biomaterial implanted into the human body depends entirely on its biocompatibility and surface properties. Therefore, in order to improve the performance of biomaterials in biological systems modification of their surface is necessary. One of most commonly used method of implant materials surface modification is electrochemical anodization and this method is reviewed in the present work.Aim of the presented review article is to explain the electrochemical anodization process and the way in which the nanotubes are formed by anodization on the metallic material surface. Influence of anodizing parameters on the nanotubes characteristics, such as nanotube diameter, length and nanotubular layer thickness, are described, as well as the anodized nanotubes influence on the material surface properties, corrosion resistance and biocompatibility.

Fabrication of broadband antireflective black metal surfaces with ultra-light-trapping structures by picosecond laser texturing and chemical fluorination

A hybrid method consisting of ultrafast laser-assisted texturing and chemical fluorination treatment was applied for efficiently enhancing the surface broadband antireflection to fabricate black titanium alloy surface with ultra-light-trapping micro-nanostructure. Based on the theoretical analysis of surface antireflective principle of micro-nanostructures and fluoride film, the ultra-light-trapping micro-nanostructures have been processed using a picosecond pulsed ultrafast laser on titanium alloy surfaces. Then fluorination treatment has been performed by using fluoroalkyl silane solution. According to X-ray diffraction phase analysis of the surface compositions and measurement of the surface reflectance using spectrophotometer, the broadband antireflective properties of titanium alloy surface with micro-nano structural characteristics were investigated before and after fluorination treatment. The results show that the surface morphology of micro-nanostructures processed by picosecond laser has significant effects on the antireflection of light waves to reduce the surface reflectance, which can be further reduced using chemical fluorination treatment. The high antireflection of over 98 % in a broad spectral range from ultraviolet to infrared on the surface of metal material has been achieved for the surface structures, and the broadband antireflective black metal surfaces with an extremely low reflectance of ultra-light-trapping structures have been obtained in the wavelength range from ultraviolet–visible to near-infrared, middle-wave infrared. The average reflectance of microgroove groups structured surface reaches as low as 2.43 % over a broad wavelength range from 200 to 2600 nm. It indicates that the hybrid method comprising of picosecond laser texturing and chemical fluorination can effectively induce the broadband antireflective black metal surface. This method has a potential application for fabricating antireflective surface used to improve the photothermal or photoelectric conversion efficiency of solar installations and enhancing the surface wave-absorbing capacity of devices.

Cyclic delamination behavior of plasma-sprayed hydroxyapatite coating on Ti–6Al–4V substrates in simulated body fluid

This study aimed to clarify the effect of a simulated body fluid (SBF) on the cyclic delamination behavior of a plasma-sprayed hydroxapatite (HAp) coating. A HAp coating is deposited on the surfaces of surgical metallic materials in order to enhance the bond between human bone and such surfaces. However, the HAp coating is susceptible to delamination by cyclic loading from the patient's gait. Although hip joints are subjected to both positive and negative moments, only the effects of tensile bending stresses on vertical crack propagation behavior have been investigated. Thus, the cyclic delamination behavior of a HAp coating was observed at the stress ratio R=−1 in order to determine the effects of tensile/compressive loading on the delamination behavior. The delamination growth rate increased with SBF immersion, which decreased the delamination life. Raman spectroscopy analysis revealed that the selective phase dissolution in the HAp coating was promoted at interfaces. Finite element analysis revealed that the energy release rate Gmax showed a positive value even in cases with compressive loading, which is a driving force for the delamination of a HAp coating. A prediction model for the delamination growth life was developed that combines a fracture mechanics parameter with the assumed stress-dependent dissolution rate. The predicted delamination life matched the experimental data well in cases of lower stress amplitudes with SBF.

Controlled hydrophilic/hydrophobic property of silica films by manipulating the hydrolysis and condensation of tetraethoxysilane

Controlling surface wettability is an important road to afford the materials with anticipated functional properties, such as anti-fogging, anti-icing and self-cleaning. Manipulating the surface topography and chemical composition is a promising strategy to achieve the expected functional properties. Herein, we concurrently realized the control of surface topography and chemical composition of the film materials via exploiting a simply one step method through the hydrolysis and condensation of tetraethoxysilane (TEOS) to form silica sol-gel films. By adjusting the amount of water, TEOS and basic catalyst, the hydrophilic or hydrophobic chemical groups on the silica particles surface were well controlled. As a result, the sol-gel silica films exhibiting a controllable and wide range contact angles from 7.7±1.5° to 121.6±1.8° were obtained by this simple one-step method. The inorganic nonmetallic, metallic and polymer materials surface could maintain different wettability by the modification of controlled wettability silica films. Furthermore the wettability of silica film could be easily changed from hydrophobicity to superhydrophilicity through a heat-treatment due to the decrease of hydrophobic chemical groups conforming to the time-temperature equivalence principle. Raising temperature and extending holding time were equivalent to chemical bond breaking which result in the wettability change of silica films.

On the Characterization Method of Nano Boron Nitride Material Based on AFM

Boron nitride materials have some excellent features, such as high temperature resistance, chemical resistance, good electric performance and radiation resistance . Along with the development of science and technology, boron nitride materials are made into coating widely, put it in the surface of metallic materials or non-metallic materials, can extend their service life significantly[1]. Atomic force microscope (AFM) is widely used for nanoscale morphology characterization and submicron scale structure material, simple sample preparation is its advantage. [2] Based on the domestic boron nitride coating as the research background, using AFM simulate the surface nanostructures of three dimensional, and evaluate the flatness of boron nitride ceramic coating which made by plasma spraying method and chemical vapor phase precipitation method respectively. The results show that the coating prepared with plasma spraying is more dense, surface flatness is smaller, surface roughness uniformity is better.

Development of protein markers for evaluating the blood compatibility of biomaterials: Validation of identified markers by comprehensive multivariate proteomic analysis for plasma proteins adsorbed on the surface of metal materials for stents

Development of protein markers for evaluating the blood compatibility of biomaterials: Validation of identified markers by comprehensive multivariate proteomic analysis for plasma proteins adsorbed on the surface of metal materials for stents

金属材料表面に微細パターンを有した材料の摩擦特性評価

金属材料表面に微細パターンを有した材料の摩擦特性評価

Particularity of the Forming Barcode Image on the Surface of Machine Parts when Marking with a Pulsed Laser

The article is devoted to some aspects of laser marking technology for machine parts. We consider the local impact zone effect of the pulse laser beam on the surface of metal materials. The results describing the influence of process parameters on the quality of the being marked images by pulsed laser are submitted. The examples of using barcode marking on several materials for machine parts in selected technological modes of installation are given.

Quantification of Fe-Base Alloy Degradation after Immersion Test

A new FeMnSi metallic alloy is proposed as biodegradable material with applications in medical field. The corrosion behavior in simulated body fluids is evaluated after immersion for 14 days. The metallic biodegradable material surface was analyzed with a SEM (2 and 3D)+EDAX equipment. The effects of the solution on the metallic surface present an area with pitting corrosions, marks around 10 µm in depth, and a different one with new chemical compounds form from biological solution with good stability on the surface. Even if is a new biodegradable material based on iron simmilar results about the surface behavior were obtain by other researchers on different FeMnSi chemical compositions.

UNSM 위한 20 kHz급 초음파 장치 개발

Article history: Ultrasonic nanocrystal surface modification (UNSM) is an example of a nanoscale-surface modification that has become noticeable because of its effects on the mechanical improvement of metallic materials. UNSM equipment needs to be both utilized and improved. The equipment is based on an ultrasonic waveguide whose role is to strike surfaces of metallic materials to achieve nanoscale deformation. In this paper, we introduce the development of one kind of UNSM equipment. Using piezoelectric elements, we repeatedly design and fabricate a 20-kHz ultrasonic waveguide. With respect to the composition of the equipment, the waveguide is automatically transferred by two axial stages automatically. In addition, a static force is constantly applied by pneumatic devices. We perform an experiment to verify the feasibility of the equipment.

Order of Dry and Wet Mixed-Length Self-Assembled Monolayers

Functionalizing the surface of metal and oxide materials with self-assembled monolayers is an elegant method for tuning the chemical properties of the surfaces. The properties of a coated surface depend on both the chemical nature of the termination as well as the order of the monolayer. One commonly used platform is alkylsilanes on silica surfaces. Here we characterize the disorder of self-assembled monolayers having a mixture of two monomer lengths using sum-frequency generation (SFG) and Fourier transform infrared spectroscopy. We find that mixed monolayer order varies smoothly as a function of composition. The mixed monolayers are more disordered than either pure monolayer, and of the pure monolayers, the shorter monolayer is more disordered. The nonlinear relationship between monolayer disorder and composition, along with atomic force microscopy images, suggests completely homogeneous mixing or very small domains of the monomers. The order of the monolayers as determined by SFG spectroscopy does not ...

Possible Mechanisms of Capacitance Enhancement under Magnetic Field: Charge Density Gradient Modulation, Electron Gas Excitation and oscillatory Magnetization-Polarization Coupling

Possible mechanisms of capacitance enhancement by a magnetic field have been analyzed. Through semiclassical description of charge movement under a magnetic field, it can be shown that the charge density gradient, a term coupled with magnetic field strength, could be used to augment the magnetocapacitance. Also a magnetic field could enhance capacitance on the polarized metallic material surface due to the electron gas excitation. Finally, a magnetic field could produce oscillation in the capacitance when relating the polarization with the magnetization through the modification of standard free energy model. By deriving these mechanisms, it can be seen that these approaches are of potential for exploring tunable dielectric materials.

Modeling and experimental study of oil/water contact angle on biomimetic micro-parallel-patterned self-cleaning surfaces of selected alloys used in water industry

In the present study, the wetting behavior of surfaces of various common metallic materials used in the water industry including C84400 brass, commercially pure aluminum (99.0% pure), Nickle–Molybdenum alloy (Hastelloy C22), and 316 Stainless Steel prepared by mechanical abrasion and contact angles of several materials after mechanical abrasion were measured. A model to estimate roughness factor, Rf, and fraction of solid/oil interface, ƒso, for surfaces prepared by mechanical abrasion is proposed based on the assumption that abrasive particles acting on a metallic surface would result in scratches parallel to each other and each scratch would have a semi-round cross-section. The model geometrically describes the relation between sandpaper particle size and water/oil contact angle predicted by both the Wenzel and Cassie–Baxter contact type, which can then be used for comparison with experimental data to find which regime is active. Results show that brass and Hastelloy followed Cassie–Baxter behavior, aluminum followed Wenzel behavior and stainless steel exhibited a transition from Wenzel to Cassie–Baxter. Microstructural studies have also been done to rule out effects beyond the Wenzel and Cassie–Baxter theories such as size of structural details.

Effective mineral coatings for hardening the surface of metallic materials

The structural changes that occur in the surface and surface layers of steel 20Kh13 and titanium alloy PT-3V (Russian designation) samples after each stage of hardening due to a formed mineral surface layer are studied by optical microscopy, transmission electron microscopy, and scanning electron microscopy. Electric spark alloying, pressing, and ultrasonic processing are used to reach the effect of volume compression of the base metal and the mineral in the plastic deformation zone. As a result, applied mineral particles concentrate in preliminarily created microvoids in a thin surface layer. The surface layer thus modified acquires a high hardness and wear resistance. Durometry shows that the hardness of the processed sample surfaces increases more than twofold. Therefore, the developed technology of creating a mineral coating can be used to increase the tribological properties of the surfaces of the parts, units, and mechanisms of turbine, pump, and mining equipment, which undergo intense wear during operation.

Multi Fractal Characteristic of Metal Material Worn Surface with Plant Abrasive

Based on the multi-fractal theory and SEM image, the multi-fractal property of the plant abrasive to metal surface was studied. The result shows that the characteristic parameters of △α and △f of the multi-fractal spectrum on can reflect the morphology features of the worn surface, which are connected with volume wear, so they are regarded as characterization parameters in quantification on the surface of metallic material that is worn by plant abrasive. 15 mm.

Helmholtz Fermi surface harmonics: an efficient approach for treating anisotropic problems involving Fermi surface integrals

We present a new efficient numerical approach for representing anisotropic physical quantities and/or matrix elements defined on the Fermi surface (FS) of metallic materials. The method introduces a set of numerically calculated generalized orthonormal functions which are the solutions of the Helmholtz equation defined on the FS. Noteworthy, many properties of our proposed basis set are also shared by the FS harmonics introduced by Philip B Allen (1976 Phys. Rev. B 13 1416), proposed to be constructed as polynomials of the cartesian components of the electronic velocity. The main motivation of both approaches is identical, to handle anisotropic problems efficiently. However, in our approach the basis set is defined as the eigenfunctions of a differential operator and several desirable properties are introduced by construction. The method is demonstrated to be very robust in handling problems with any crystal structure or topology of the FS, and the periodicity of the reciprocal space is treated as a boundary condition for our Helmholtz equation. We illustrate the method by analysing the free-electron-like lithium (Li), sodium (Na), copper (Cu), lead (Pb), tungsten (W) and magnesium diboride (MgB).

In Situ Formation of Carbon Nanomaterials on Bulk Metallic Materials

Carbon nanomaterials were synthesized in situ on bulk 316L stainless steel, pure cobalt, and pure nickel by hybrid surface mechanical attrition treatment (SMAT). The microstructures of the treated samples and the resulted carbon nanomaterials were investigated by SEM and TEM characterizations. Different substrates resulted in different morphologies of products. The diameter of carbon nanomaterials is related to the size of the nanograins on the surface layer of substrates. The possible growth mechanism was discussed. Effects of the main parameters of the synthesis, including the carbon source and gas reactant composition, hydrogen, and the reaction temperature, were studied. Using hybrid SMAT is proved to be an effective way to synthesize carbon nanomaterials in situ on surfaces of metallic materials.

Erosion Wear Analysis of Coated and Uncoated Ductile Materials at Different Velocities and Angles

Wear is the gradual, layer-by-layer destruction of the surface of metallic materials by mechanical action of erodents,or passage of slurry. The wear of metals occurs upon the frictional rubbing of surfaces, wear, and cavitations, as well as upon the action of strong gas or liquid currents upon a surface, especially at high temperatures and pressures. Various parts of jet engines, nuclear reactors, and steam turbines boilers and pipes in the thermal power plants and cement industries where the pipe carries the slurry were subjected to destruction by erosion. Increased resistance of parts against erosion can be achieved by improving process technology or unit design and by selecting more suitable material; heat treatment also increases resistance against erosion. Structural materials have been developed that provide durable operation of parts under erosive conditions, such as some niobium and molybdenum alloys. In the present work the effect of erosion wear on 18Cr8Ni based steel strip coated with Epoxy polyester and powder coating has been investigated experimentally. Comparison of the erosion resistance and loss of metal for different mass flow rate and angle’s are done.