International Journal of Surface Science and Engineering (11 papers in press)
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
Keywords: Coating; Wear-Resistant; PVD; Wear; Temperature; Automotive.
Characterization and Comparison of Disc Brake Pads of Heavy Vehicles by Experimental Methods
by Polat TOPUZ, Zekeriya Yaşar CÖMERT, Ahmet TOPUZ
Abstract: In this study, characteristics of disc brake pads of heavy vehicles produced by 3 different manufacturers were compared experimentally. The former pad is the original (OEM), the latter pad is the subsidiary industrial production (SIPM), and the third pad is the Turkish production (TM). These brake pads which have different compositions; components, wear and friction characteristics, mechanical and physical properties were investigated and also the environment and usage were compared among each other.
For chemical analyses, scanning electron microscopy EDS (Energy Dispersive Spectroscopy) system and XRF (X-ray fluorescence) were used. TG (Thermal Gravimetric Analysis) were performed to determine the mass losses in the pad materials. Wear friction tests of pads were made according to JIS D 4411 standard. Apart from these, the hardness, density and internal shear strength values of the pads are measured.
Keywords: Heavy vehicle disc brake pads; compositions; wear; friction; environment and usage.
The Effect of Wollastonite Silane-Treatment on Mechanical and Tribological Performance of NAO Brake-Pads
by May Abdel-Latif, Nabil El-Tayeb, Vishal Mahale, Jayashree Bijwe
Abstract: The current study aims to investigate the effect of silane-treatment of wollastonite on the mechanical, tribological performance of non-asbestos organic frictional brake pad material. Two main friction lining specimens in the shape of brake-pads containing treated wollastonite (Wt) and untreated wollastonite (Wu) were produced to carry on the experiments. All produced samples were characterised and examined for their mechanical, chemical and tribological properties.
The experimental results show that all parameters of tribological performance are within the acceptable standard range and that the tribological performance for all samples is almost the same in terms of friction coefficient and fade performance. Regarding wear, recovery performance and Disc Temperature Rise (DTR), Wt samples offer better performance than Wu samples which was attributed to the good adhesion between wollastonite and the polymeric matrix after treatment. Moreover, Scanning Electron Microscopy analysis is done on the tested samples and show overall improved surface of Wt than Wu. Finally, for full use of wollastonite silane-treatment advantages, it is recommended to be used in vehicles with less severe operating conditions such as motorbike and alike.
Keywords: Brake Materials; Non-Asbestos Organic (NAO) Materials; Frictional Materials.
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.