International Journal of Surface Science and Engineering (9 papers in press)
Wet-Chemical Etching of GaAs (211)B Wafers for Controlling the Surface Properties
by Selin Ozden, Mumin Mehmet Koc
Abstract: Substrate surface plays an important role to achieve high performance infrared devices and high-quality film layers. GaAs (211)B wafers were intensively used in infrared detector applications. Despite epiready wafers can easily be found on the market, most of them have defects and contaminations due to their fabrication processes. The defects and contaminations on wafers may have deleterious effects on thin film growth and detector applications. To overcome such problems, various chemical treatments should be implemented prior to thin film growth. In this study, to understand the effect of wet chemical cleaning process on epi-ready (211)B GaAs wafers, piranha solution-based wet chemical etching performed. After these treatments, the surfaces of GaAs wafers were investigated by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Energy Dispersive X-ray Spectroscopy (EDX) were used to assess the chemical composition of the surface. The vibrational modes and two-dimensional maps were observed by a Raman Spectroscopy.
Keywords: Chemical Etching; Gallium Arsenide; Surface Defect Control; Raman Spectroscopy; Atomic Force Microscopy; Scanning Electron Microscopy.
Microscopic analysis of the Sol-Gel alumina grinding wheel after the introduction a synthetic organosilicon polymer- based impregnate dedicated for near dry grinding processes
by Krzysztof Nadolny, Wojciech Kapłonek, Magdalena Niemczewska-Wójcik, Mioriţa Ungureanu
Abstract: In the paper, analysis of the surface condition of 1-351010-SG/F46G10VTO grinding wheels with microcrystalline sintered alumina abrasive grains and a glass-crystalline bond after the impregnation process using a synthetic organosilicon polymer (silicone) has been presented. The main goal was to compare the values of selected surface topography parameters obtained from the active surfaces of an impregnated set of grinding wheels with those same parameters obtained from a non-impregnated reference wheel. The analysis proved that an elaborated method of introducing the impregnating substance is effective and allowing to uniformly its distribution throughout the body of the grinding wheel. However, the introduction of impregnating substance caused a reduction (average from 13% to 50%) in the values of the selected 3D parameters of grinding wheel active surface (GWAS) roughness. An analysis described in this work is the basis of an objective evaluation of the experimental results of the grinding process conducted with use of that kind of wheels.
Keywords: microscopy analysis; sol-gel alumina grinding wheel; silicone impregnation; hard to cut materials; internal cylindrical grinding.
Dry sliding friction and wear behavior of developed copper metal matrix hybrid composites
by Manvandra Kumar Singh, Rakesh Kumar Gautam
Abstract: In the present investigation, dry sliding friction and wear behavior of developed copper-basedrnhybrid composites were studied. Tungsten carbide (WC), zirconia (ZrO2), alumina (Al2O3) ofrngrade A6 and chromium (Cr) hybrid reinforcements were utilized to develop various copperbasedrnhybrid composites using liquid stir-casting technique. The developed hybrid compositesrnwere characterized by X-rays diffraction (XRD), high-resolution scanning electron microscopern(HR-SEM), energy-dispersive analysis of X-rays (EDAX), relative density and Vickers hardness.rnDeveloped hybrid composites show improved Vickers hardness compared to its copper matrixrnwhile relative density was found lower. Dry sliding friction and wear behavior of the developedrnhybrid composites were studied using pin-on-disc tribometer at variable normal load, constantrnsliding speed and sliding distance. Hybrid composites exhibited low wear compared to its copperrnmatrix, particularly (WC+Al2O3+Cr) hybrid reinforced composites revealed better wearrnresistance among all. Fluctuating nature of the coefficient of friction was observed in all thernmaterials. However, developed hybrid composites revealed higher coefficient of frictionrncompared with its matrix. The worn surfaces were analyzed using scanning electron microscopyrn(SEM), EDAX and optical profilometer to discuss the friction and anti wear mechanism involvedrnin developed materials.
Keywords: metal matrix hybrid composite; stir-casting; X-ray diffraction; wear; worn surface;rnhardness; coefficient of friction; dry sliding; color-mapping; profilometer; surface roughness.
Finite Element Based Contact Analysis of a Radially Functionally Graded Hemisphere and a Rigid Flat
by Tamonash Jana, Anirban Mitra, Prasanta Sahoo
Abstract: In the present work, a normally loaded contact between a radially functionally graded hemisphere and a rigid flat is analyzed in perfect slip condition for different values of gradient/inhomogeneity parameter. The analysis was performed with an axisymmetric model in commercial finite element software ANSYS 18.2. The Youngs modulus, yield strength and tangent modulus (for bilinear isotropic hardening) are varied according to an exponential function. The effect of the inhomogeneity parameter on different contact behaviors e.g. contact area, contact pressure, contact stresses etc. of the hemisphere are obtained. Stress and deformation behavior of the contact interface as well as of the entire hemisphere has been analyzed. It is observed that for negative inhomogeneity parameter, while being deformed by the rigid flat, the summit of the hemisphere loses contact with flat and sinks in to have a concave shape at the top of the hemisphere. This phenomenon has not been reported in established literature yet.
Keywords: FGM; graded contact; hemispherical contact.
SEM-based observations and analysis of the green silicon carbide (SiCg) grinding wheel active surfaces after the graphite and silicone impregnation process
by Wojciech Kapłonek, Krzysztof Nadolny, Mioriţa Ungureanu, Danil Pimenov, Bartosz Zieliński
Abstract: In the paper, initial studies focused on observations and analysis of the effects of the impregnation process of the grinding wheel active surface (GWAS) 1-35
Keywords: scanning electron microscopy; SEM micrograph; grinding wheel; green silicon carbide; impregnation process.
Electrophoretic deposition of zinc-doped hydroxyapatite coatings on titanium: Deposition kinetics and coating morphology
by Claus Moseke, Yunis Alnazal Alramadan, Elke Vorndran, Patrick Elter
Abstract: A wet chemistry reaction route was utilized to fabricate hydroxyapatite (HA) coatings with the incorporation of different amounts of zinc by electrophoretic deposition on titanium. HA powders and coatings were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray analysis. The presence of Zn had only a small impact on the crystallinity and practically no effect on the crystallite morphology of the powders and coatings. High additions of Zn apparently led to a change of the migration direction of the HA particles in the coating electrolyte and also resulted in increased crack formation during the drying process of the deposited coatings. Zn was incorporated in the HA coatings by ionic substitution and by incorporation of a low-crystalline ZnO phase, which may be advantageous for the application as a long-term reservoir for Zn as an osteoclast-inhibiting agent on biomaterials for implantation in critical bone situations.
Keywords: electrochemistry; biomaterials; calcium phosphates; surface modification; zinc oxide.
Effect of laser surface texturing on tribological behavior of grey cast iron
by B. Anil Kumar, Dinesh Babu Purushothaman, P. Marimuthu, Muthukannan Duraiselvam
Abstract: This work aims to study the effect of laser surface microtexture on the sliding behavior of grey cast iron, which is used as a liner material in internal combustion engines. The sliding wear analysis was conducted at different sliding speeds (200 rpm, 400 rpm, and 600 rpm) and a normal load of 10 N. Laser machining system was used to create micro-dimples with texture densities of 13.45% and 6.37%. The dimple sizes were observed using a scanning electron microscope, and the surface roughness was measured using the white light interferometer. The sliding wear results show that the textured samples with 13.45% densities in higher viscosity 146 mPas oil show better wear resistance with 0.1828 mm3/m wear rate and reduced friction coefficient of 0.1973. The wear morphology of the textured samples confirms the abrasive wear mechanism with minimum material removal compared with the non-textured specimen for the given applied load and sliding speed.
Keywords: Laser surface texturing; Surface roughness; Scanning electron microscope; Wear; Lubrication.
A review on plasma sprayed titanium and hydroxyapatite coatings on polyetheretherketone (PEEK) implants
by Ali Tekin Guner, Cemal Meran
Abstract: Polyetheretherketone (PEEK) is a biocompatible polymer with good mechanical strength, thermal and chemical stability and is suitable for magnetic resonance and X-ray imaging. Moreover, density and elasticity of PEEK is closer to bones compared to metals. Nevertheless, the hydrophobicity of the PEEK surface causes a soft tissue formation at the bone/implant interface that prevents direct bone apposition. Although numerous methods have been developed for improving PEEKs bioactivity, the most widely used and accepted method have been coating the surface with a thin layer of osseointegrative material by thermal spraying. Most widely used coating materials in the manufacture of orthopaedic implants have been hydroxyapatite (HAp) and titanium. Thus, this review focuses on the recent progress on HAp and Ti coatings deposited by plasma spraying methods on PEEK implants.
Keywords: Plasma spray; coating; polyetheretherketone; hydroxyapatite;
Wear of chromium nitride coating under high loads and speeds
by Shailesh kumar singh, Somnath Chattopadhyaya, A. Pramanik, Sanjeev Kumar, A.K. Basak
Abstract: This paper investigates the effect of high loads (up to 100 N) and high speeds (up to 3 m/s) on wear and friction behaviour of PVD deposited CrN coatings on cast iron substrate. Uncoated substrate materials were also tests under identical test parameters to compare the friction coefficient, wear rate, temperature generation accompanied with wear mechanism. With the increase of normal loads from 50 to 80 N the wear rate of coated sample increases from 4.59×10-5 to 6.86×10-5mm3/Nm, while the sliding speed remains constant. Temperature rise due to friction was monitored in wear tracks, and higher wear track temperature stimulates higher coating wear as well as degradation of materials. The successive increase of sliding speed as well as normal load causes an increase in temperature rise (from 65 to 178 °C) in the wear track which has an immense effect on wear resistance of the CrN coating. The wear mechanisms of the CrN coatings involve pull out of nitride particles, oxidation of wear particles, adhesive wear and a combination of fatigue delamination as evident from wear track morphology investigated by scanning electron microscope.
Keywords: Coating, Wear-Resistant; PVD, Wear; Temperature, Automotive