International Journal of Surface Science and Engineering (5 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.