International Journal of Surface Science and Engineering (10 papers in press)
Solid particle erosion studies on fibre composite with egg shell as filler materials
by M. Adam Khan, Mani Kandan, Ebenezer George, M. Uthayakumar, S. Thirumalai Kumaran
Abstract: The development on composite materials has a tremendous role in the place of metals and alloys for different engineering applications. On other hand the material selected for specific applications are prone to fail in bulk with surface defect and shear based on working conditions. Hence the challenges convince the researchers to modifying the materials with different reinforcement. In this paper glass fibre composite material was developed with and without fillers to investigate on solid particle erosion test rig. From the experiments, the surface wear and parameter influencing air jet erosion are studied in detail. The parameters involve are jet pressure, volume of erodent and exposed time at constant angle of impingement. Based on mass change erosive wear rate are empirically calculated. The surface topography of the sample are observed with electron microscopic analysis for superficial studies. Influence of process parameter are evaluated using 2k factorial design. It is confirmed that erodent behaviour and composite with filler material are dominating the erosive wear rate. The sample with polyester resin has an affinity to hold the abrasive particle as inclusion during striking of solid particle. Therefore the proposed model with natural filler in fibre reinforced surface has resistance toward erosion.
Keywords: erosion; composite; filler; wear; microscope.
Surface-modified substrates for the Langmuir Blodgett deposition of patterned ultra-thin and highly oriented collagen coatings
by Karina Ambrock, Bernd Grohe, Silvia Mittler
Abstract: As a pre-study for highly oriented collagen coatings on implants (with irregular surfaces and shapes), the Langmuir-Blodgett (LB) technology, a low-cost and straightforward approach, was pioneered. The effects of physicochemical (hydrophilic / hydrophobic) patterns and 3D-mechanical barriers present on substrate surfaces are studied in terms of the dynamics of collagen flow during LB film deposition and the formation of highly oriented coatings. Due to the large internal cohesion of collagen films only large 3D-obstacles deflect the flow of collagen and lead to film rupture, suggesting that objects (screw-threaded dental implants) with small topographic features should be easily and evenly coatable. Moreover, hydrophilic / hydrophobic / collagen patterned substrate surfaces were fabricated, by partly removing coated collagen. These substrates are outstanding for timely studies that need identical conditions but different surface properties side by side. Crystallization of barium oxalate was carried out as a proof-of-principle.
Keywords: Langmuir-Blodgett technology; collagen deposition; ultra-thin collagen coatings; highly oriented collagen; surface-modified substrates; hydrophobic substrates; hydrophilic substrates; 3d-obstacles; collagen film patterning; film-internal cohesion forces; adhesion forces; multifunctional substrate surfaces.
Mechanical and anti-wear properties of multi-module Cr/CrN coatings
by Łukasz Szparaga, Katarzyna Mydłowska, Adam Gilewicz, Jerzy Ratajski
Abstract: The objects of investigations were Cr/CrN multi-module coatings deposited using a cathodic arc evaporation method (CAPVD) on HS6-5-2C steel used as a substrates. Analyzed coatings possess 7 Cr/CrN modules of fixed thickness each, with various thicknesses of Cr and CrN layers. Aiming for the evaluation of mechanical properties of tested multi-module Cr/CrN coatings, its hardness and Young's modulus were measured, on the basis of which were determined values of H/E and H3/E2 ratios. Coatings wear and friction coefficient were measured in so called ball-on-disc test. The adhesion of the coatings was evaluated using scratch tester and was shown that main mechanism of adhesive damage of all tested coatings at higher loads are buckle spallations. All tested coatings are also characterized by good adhesion to the substrate, which is evidenced by the fact that cracked coating remains inside the scratch track. Basing on the analysis of obtained experimental results it was confirmed and explicitly shown that the thickness of the individual layers of Cr and CrN in the multi-module coating significantly affects its critical loads (in scratch test), fracture toughness and wear rate.
Keywords: thin hard coatings; PVD; anti-wear coatings; multi-layer coatings; nanoindentation; adhesion; scratch test; fracture toughness; ball-on-disc test; hard chromium replacement.
Pull-off Strength and Abrasion Resistance of Anti-corrosive Polymer and Composite Coatings
by Anna Dmitruk, Paulina Mayer, Joanna Pach
Abstract: The paper aims at presenting the results of pull-off strength and abrasion resistance tests for anti-corrosive coatings on steel substrates. It contains the measured data on the thickness of manufactured coatings in the function of the applied amount of abrasive material. Three polymeric coatings were subjected for testing: chlorinated rubber, oil-phthalic and alkyd. The analogous studies were repeated for composite coatings with alumina α-Al2O3 filler and subsequently also for the aged (72 h, -19
Keywords: anti-corrosive; coatings; abrasion resistance; pull-off strength; composites; polymers.
Effect of lubrication on the wear behavior of CrN Coating deposited by PVD process
by Shailesh Kumar Singh, Somnath Chattopadhyaya, Alokesh Pramanik, Sanjeev Kumar, A.K. Basak
Abstract: This paper investigates the effect of SAE grade 20W50 engine oil as a lubricant on the wear behavior of CrN coating deposited by PVD process at higher loads and speeds by pin on disc tribometer. The surface of coated sample in dry and wet conditions indicates that COF is decreasing from 0.38 (dry) to 0.14 (wet) at 50N load and speed 1m/s, at the same speed when load is increasing COF is decreasing. The maximum and minimum specific wear rate is 9.82
Keywords: PVD; CrN; wear; friction; lubrication; temperature.
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) 1-35×20×10 99C46K8V made of green silicon carbide (SiCg) are presented. One of the allotropic varieties of carbon (graphite) and a synthetic organosilicon polymer (silicone) was introduced into the structure of the GWAS. For an assessment of the effects of impregnation, a JEOL JSM-550LV scanning electron microscope (SEM) was used. The data acquired by this instrument are presented in the form of a set of SEM micrographs subjected to visual and computer image analysis using Image Pro®-Premier software. This software allowed one to calculate the size of the area containing the impregnate in relation to the area without a impregnate, and to determine other useful geometrical parameters. The obtained results provided information about the effects of the impregnation process, its efficiency and influence on the characteristics of the GWAS.
Keywords: scanning electron microscopy; SEM micrograph; grinding wheel; green silicon carbide; impregnation process