International Journal of Surface Science and Engineering (12 papers in press)
Ultrasonically nanostructured electric-spark deposited Ti surface layer on Ti6Al4V alloy: Enhanced hardness and corrosion resistance
by M.A. Vasylyev, M.A. Vasylyev, B.N. Mordyuk, B.N. Mordyuk, V.P. Bevz, V.P. Bevz, C.M. Voloshko, C.M. Voloshko, O.B. Mordiuk, O.B. Mordiuk
Abstract: A complex approach for the production of corrosion resistant nanostructured surface layer on the Ti6Al4V alloy is reported in this article. Surface modification was conducted using sequential application of electric discharge surface alloying (EDSA) with α-titanium and ultrasonic impact treatment (UIT) induced the nanostructuring of the EDSA-formed Ti-layer. X-ray diffraction and TEM analysis show that the applied modifications form the outmost surface layer of ~20 μm thick comprised the nanoscale grain structure with a grain size of 10-30 nm. Additionally, the UIT-induced mechanochemical oxidation of the modified surface was observed by SEM with energy dispersive X-ray microanalysis. The produced nanostructured α-titanium surface layer shows enhanced microhardness and better corrosion behaviour in saline solution than those of the original and UIT-processed Ti6Al4V alloys. Thus, the complex treatment applied can be recommended for the surface finishing of the products made of multi-phase titanium alloys, such as biomedical implants.
Keywords: nanoscale grain structures; surface layer; titanium alloys; corrosion behaviour; electric discharge surface alloying; ultrasonic impact treatment.
Experimental Investigation on the effect of Ionic Liquids (C16H36BrP and C16H36BrN) on the Tribological Performance of Neem Oil
by Panneer R, Panneerselvam T
Abstract: Ionic liquids are liquid salts, widely used in the chemical processing industry and have excellent lubricating properties. The present study focuses on the tribological performance of three different lubricants, Pure Neem oil, Neem oil with 0.5 wt. % of Ionic Liquid Tetrabutylammonium bromide (C16H36BrN) and Neem oil with 0.5 wt. % of Ionic Liquid Tetrabutylphosphonium bromide (C16H36BrP) in steel to steel interface. Considerable friction reduction and anti-wear capabilities have been confirmed when Neem oil is added with 0.5 wt. % Tetrabutylphosphonium bromide. The use of this fluid has reduced the frictional force at a uniform rate, and deep, broad wear scars or blisters or eruptions on the sides of the wear scars are not seen. The Viscosity, Density and Wear Resistance values also support this conclusion. The outcome of the research shows that Neem oil along with Tetrabutylphosphonium bromide can replace the existing conventional, unsustainable hydrocarbon and synthetic based lubricants.
Keywords: Neem oil; Ionic liquids (ILs); Frictional Force; Temperature; Viscosity; Volume Loss; Wear Resistance; Wear Scars.
Nanomechanical and Nanotribological Properties of Self-lubricating Ti/MoS2 Nanocoating at Nanoscale level
by Summera Banday, M.F. Wani
Abstract: Ti/MoS2 coating of thickness 99.79 nm was prepared by pulse laser deposition method on Al-Si substrate. Mechanical and nanotribological properties of Ti/MoS2 coating were obtained by carrying out nanoindentation, nanoscratch and nanowear tests at low loads. It was observed that Youngs modulus and nanohardness of Ti/MoS2 coating decrease with increasing load. The coefficient of friction also decreases with the increase in sliding distance, which proves that Ti/MoS2 coating have self-lubricating property. The wear rate of Ti/MoS2 coating increases from 5.7 x10-10 mm3/Nm to 2.1 x 10-9 mm3/Nm with the increase in load. Scanning probe microscope images of Ti/MoS2 coating shows the plastic flow of coating with no debris and cracks on the surface. It indicates that the abrasive wear is the main wear mechanism.
Keywords: Nano-Coating; Nanoindentation; Nanoscratch; Nanowear.
Experimental investigation on the efficiency of the wrap around nozzle as coolant delivering system for ultra high speed grinding
by Naoufel Ben Moussa, Farhat Ghanem, Nizar Ben Salah, Nabil Ben Fredj
Abstract: In recent years, attention has been given to develop efficient and optimised cooling systems for grinding to reduce the process cost and to limit the health hazards of operators. In ultra-high speed grinding this issue is particularly complex because the thick air barrier rotating with the grinding wheel prevents the grinding fluid from reaching the grinding zone to cool down the grinding wheel working surface and the workpiece. In this paper, results of experiments conducted to characterize the application of the wrap around nozzle (WRN) to the ultra high speed plunge surface grinding are presented. Experiments were conducted in a peripheral wheel speed ranging from 50 to 380m/s and the effects of the nozzle position, the total flow rate and the wheel speed on the nozzle efficiency were investigated. The existence of a critical peripheral wheel speed vsc up to which the WRN delivers the coolant under both mechanisms of the shoe type and the jet type nozzles was made evident. The efficiency of the WRN was found to depend mainly on the total flow rate and on the nozzle position. This efficiency was compared to a cooling system composed of double air scrapper and a conventional jet type system. Experiments showed that the WRN has higher and much stable cooling efficiency in the ultra-high-speed range of the grinding wheel.
Keywords: ultra high speed grinding; wrap around nozzle; air scraping; useful flow rate; cooling efficiency.
Study of the Additives Influence in the CMP slurry for the Surfaces Planarization Covered by Selective Transfer
by Filip Ilie, George Ipate
Abstract: Chemical Mechanical Planarization (CMP) seems to be the only effective technique to achieve both local and global planarization (polishing), used to remove the excess of metal, and obtained in selective-transfer process and for improving the polishing and micro-machining process. Also, CMP is the technology that ensures the patterns formation the surfaces with higher resolution and planarity.
The selective-layer CMP process assumes of selective-layer surface oxidation by an oxidizer, protection of the oxidized selective-layer surface by an inhibitor and the removal of the passivation layer from the top of protrusions by the pad and abrasive particles mechanical action. The selective-layer slurry consists of hydrogen peroxide (H2O2) as the oxidizer, organic acids as the etching agents, benzotriazole (BTA) as a corrosion inhibitor and silica (SiO2) particles as abrasive. Among investigated acids, citric acid was chosen as a complexing and etching agent for the preparation of selective-layer slurry due to its higher removal rate of the selective-layer and better stability of slurry. The removal rate of the selective-layer was dependent on the organic acids kinds used, but the etching was not. The BTA controlled adding in slurry could change the removal and etching rate of the selective-layer. In this paper is analyzes the effect of additives in CMP slurry on the polishing of surfaces covered through selective-transfer. Also, it was analyzed the effect of additives in SiO2 based slurry on selective-layer CMP process, considering removal, etching rates, as well as the behavior of the slurry with different types and concentrations of additives in various proportions.
Keywords: Additives; CMP slurry; Covered surfaces; Selective-layer; Solid particles; Removal and etching rate.
Injection water jet peening of carburized 18CrNiMo7-6 steel surfaces
by Yongtao Ma, Lundun Zhang, Jiancheng Liu, Lanrong Liu
Abstract: A compressive residual stress field (CRSF) can improve the fatigue life of machined parts. Injection water jet peening is a new way of inducing compressive residual stress in the surface layer. A carburized 18CrNiMo7-6 gear steel was tested using injection peening under different conditions. The main variables included pressure, nozzle velocity and stand-off distance. The surface hardness was improved up to 63.4HRC from its original hardness of 56.3HRC. The maximum residual stress reached -1240MPa at a depth of 150
Keywords: injection water jet; peening; carburized steel; residual stress; surface quality.
NUMERICAL MINIMIZATION OF ABRASIVE-DUST WEAR IN INTERNAL COMBUSTION ENGINES
by AbdulAziz Alfadhli, Abdullah Alazemi, Emad Khorshid
Abstract: This paper presents a mathematical model to predict the abrasive wear of piston ring and cylinder sleeve in petrol and diesel engines due to dust particles. A parametric study is conducted on different group factors such as the abrasive action of the medium, engine design parameters and engine physio-mechanical properties of the materials. Qualitative and quantitative comparisons of the results obtained from the mathematical model, with published results reveal that it accurately predicts the effect of numerous factors on the wear process for the piston ring and cylinder sleeve. The model capabilities are demonstrated by the effect of air filtration efficiency on the engine component wear rate. It is found that dust particle size and concentration, which are related to air filtration, have major effects on piston ring and cylinder sleeve wear rates. The numerical results show that the wear rate of both the piston ring and cylinder sleeve can be reduced by 80% when the air filter efficiency is increased from 97.8% to 99.4%.
Keywords: Abrasive wear; Air Filtration; Internal combustion engine; Dusty environment; mathematical modeling.
The Effect of Different Sputtering Parameters on Coating Thickness and Hardness in MoS2 Coated Films With and Without Interlayer
by Mehmet POYRAZ, Recai Fatih Tunay
Abstract: The aim of this study is; to examine the effect of different sputtering parameters on coating thickness and hardness in MoS2 films which are deposition of Radio Frequency (RF) magnetron sputtering method. Therefore; 440C steel substrates are coated with MoS2 thin films which exhibit lubrication as a solid lubricant and low friction characteristic during shear. By using the Radio Frequency Magnetron Sputtering Technique; MoS2 films with no interlayer and (Ti/Cr) with interlayer were deposited on the AISI 440C substrates with different coating depositon parameters. During the coating, by changing the deposition parameters such as the substrate deposition temperature and Radio Frequency sputtering power, steel disc groups which are coated in 15 different deposition parameters were obtained. Thicknesses of the films coated with different parameters; were measured from the lateral sections of the coatings by using a SEM. After the coatings, the surface topographies of the samples were observed at different magnifications using SEM. The composition and structure of the coating thickness were analyzed by Energy Dispersive Spectroscopy (EDS). A nano-indentation system was used to determine the hardness and elesticity modules of the coatings. Coating thicknesses ranging from 0.62 to 5.18
Keywords: Thin film coating; Film hardness and thickness; Physical Vapour Deposition; Radio Frequency magnetron sputter film coating.
Identification of Materials and Coatings to Minimize/Eliminate Wankel Rotary Engines Apex Seal/Trochoid Wear Chatter
by Aakash Gupta, Sanjay Jayaram, Harold McCormick
Abstract: A very well-known problem is existing in Wankel rotary engine that leads the engine to seize before it achieves operational loading conditions. Leading engine manufacturers like Ford, Curtiss Wright, and Bentley have studied this problem and have cited/developed series of patents, but the root cause of the problem has not been completely understood and studied. Existing research literature shows one of the primary indications to cause engine seizure are the chatter marks, popularly known as the devils nail marks. An analogy drawn from Shoberts carbon-brush vibration and chatter analysis concludes coefficient of friction, being the driving cause of chatter initiation, and is directly proportional to the angle between the contact elements. The present study focuses on performing bench testing on the LS-9 bench test fixture to rank the combinations of chosen materials and coatings resulting in lowest friction and reduced chatter. A total combination of eleven materials and coatings were analyzed and tested on the LS-9 bench test fixture. It was found that titankote with PVD coating and nikasil coating with diamond particles on A-2 tool steel performed the best, resulting in no wear, scuffing or chattering, with an increased surface smoothness. Average coefficient of friction of the tests performed were found to be 0.15. The lowest coefficient of friction measured was 0.06 with HTCS-150 hard trochoid and C-Lee Cook apex seals, however some wear and scuffing were observed with this combination and thus it wasnt ranked amongst the best. The maximum average face wear reduction obtained was 15 microns on titankote with PVD coated trochoid and 18 microns on ceramic apex seal. Also, wire EDM surfaces were found better in resulting lower friction and smoother post-test roughness, against ball milled surfaces.
Keywords: Chattering; Wear; Scuffing; Surface Roughness; Surface Finish; Coefficient of Friction; Additive Manufacturing; Thermal Conductivity; Tribology;.
Surface Morphology Investigation of Miniature Gears Manufactured by Abrasive Water Jet Machining
by Kapil Gupta, M. Adam Khan
Abstract: In this paper, abrasive water jet machining is used to manufacture miniature spur gears. Water jet pressure, abrasive flow rate and stand-off-distance are the varying input parameters to study the surface morphology (surface roughness and topography) of the machined gears. From the investigation, the water jet pressure has highly influenced (with 47% contribution) the surface quality and found as a predominant process parameter. SEM micrograph study found that wear scars and clinging effects are the major surface defects found over the machined surfaces of the gear teeth. Maximum and minimum peaks of the wear tracks are observed with white light spectroscope. The best surface morphology was achieved at a jet pressure of 350MPa with an abrasive flow rate of 225g/min at a 1mm stand-off distance. The present work identifies the potential of AWJM process for manufacturing of high quality miniature gears.
Keywords: abrasive; gear; machining; surface; wear.
Corrosion and passive film study of Cermet-coatings deposited by high-velocity oxygen fuel method in an acidic environment
by Akbar Niaz
Abstract: Cermet coatings are used for wear resistance applications, and it is generally understood that deterioration predominantly occurs due to frictional and erosion forces between two parts of mediums. The electrochemical corrosion of the Cermet coating is partially studied. The focus of the present work is on the detailed electrochemical corrosion study of WCCoCr coatings. The mild steel samples surfaces were cleaned by sandblasting before depositing multi-layers of coatings carried out by the high-velocity oxygen fuel method. The electrochemical corrosion testing was carried out by recording potential vs. time curves, potentiodynamic polarization, and impedance spectroscopy. The formation of oxides in the air and as a function of increasing voltage is studied by X-ray photoelectron spectroscopy. Our experimental results revealed that under stagnant conditions, electrochemical properties significantly change with time. The coating deterioration is expected to be worse in dynamic conditions where coatings surfaces are renewed by rubbing, sliding, or erosion conditions.
Keywords: Cermet coatings; Electrochemical testing; Corrosion degradation; Impedance spectroscopy; Coating passivation; Oxides characterization; WCCoCr coatings.
LONG-TERM WEAR PREDICTION OF ZIRCONIA ON ALUMINA CERAMIC FOR HIP PROSTHESIS
by Shankar Subramaniam, Nithyaprakash R, Sugunesh A.P, Uddin M.S
Abstract: This paper aims to predict wear of hard zirconia-on-hard alumina ceramic hip bearing couple for 20 years of lifetime by considering a realistic wear coefficient. Past studies in hip wear prediction have considered a fixed wear coefficient determined for a shorter sliding distance and used this for long-term wear prediction. In this study, pin-on-disc test between the zirconia and alumina bearing materials for a sliding distance of 60 km has been conducted in a dry and lubrication condition to determine friction and wear coefficient for initial running-in and subsequent steady-states. Finite element method has been employed to compute cumulative linear and volumetric wear of implant for 20 million cycles using the calculated wear coefficient values. Wear prediction showed lesser cumulative linear and volumetric wear for steady state wear coefficient when compared with running-in wear coefficient.
Keywords: Alumina; Zirconia; Wear Coefficient; Hip Prosthesis; FEM; Wear.