International Journal of Surface Science and Engineering (8 papers in press)
Effect of Sputtering with Ions on Field Emission from Different Metallic Surfaces
by Süleyman Soykarc?, Pavel Serbun, Yahya Öz, Dirk Lützenkirchen-Hecht
Abstract: The main field limitations of modern particle accelerators play an important role in various studies. One of the most important limitations is the enhanced field emission (EFE) having a parasitic effect on the quality of accelerators. Many studies concentrate on different methods for improving the surface quality of cavity metals which is correlated to the beforementioned effect. This manuscript considers a different approach by ion irradiation. Systematic analyses of the surfaces and the EFE from polycrystalline copper (Cu) and large grain niobium (Nb) before and after argon-ion (Ar+) irradiation are performed. Results show that the suppression of the EFE might be achievable with this strategy which might yield an enhanced performance of particle accelerators that use normally conductive structures since the surface roughness Ra of Cu samples drops from 35
Keywords: accelerator technology; field emission; irradiation effects; parasitic effects; sputtering; surface quality.
Evaluation of fretting wear damage on coated system using computer vision technique
by Kyungmok Kim
Abstract: This article describes a simple method to evaluate fretting-wear damage of low friction coatings using computer vision techniques. Evaluation is based on the relationship between a substrate area appearing on a contact surface and the number of fretting cycles. Quantification of the substrate area enables the evaluation of fretting damage and the prediction of the remaining lifetime of the coating. Substrate regions that appeared on a contact surface were detected by using Otsu threshold on V-channel image and thresholds for H-and S-channel images in HSV colour model. The thresholds for H-and S-channel images were determined with experimental data. The coefficient of a fretted area (COA) was introduced for quantifying fretting wear damage of a coating. Direct comparison between calculated COA values and measured ones were carried out. It was demonstrated that the proposed method allows effective evaluation of fretting-wear damage within a 5% error margin.
Keywords: fretting wear; computer vision; otsu threshold; low friction coating.
Tribological investigation of Molybdenum disulphide nanoparticles and Graphene nanoflakes as lubricant additives in Karanja oil
by Zahid Mushtaq, M. Hanief
Abstract: This study was directed at improving the lubricating potentials of Karanja oil (KO). KO was additivated with nano-sized MoS2 and graphene in assorted form and the experimentation was executed on a four-ball tester according to ASTM D-4172 standards. The results proved that their addition eminently brought down the wear of the test balls. Minimum wear scar diameter was recorded at 0.5% additivation which was cut down by 27.33% as compared to the virgin KO. The variation of the coefficient of friction (cof) and wear with load and speed was studied on a ball-on-disc tribometer for two different tribo-pairs. The surface characteristics of the wear scars were revealed under FESEM, optical microscope, and 3D surface profilometer. The cof and wear rate was reduced with both load and speed. This was attributed to the formation of tribo-layer on the scar surfaces as characterised by Raman analysis.
Keywords: Karanja; graphene; friction; wear; biolubricant; nano-lubricant; nano-additives.
The Mechanical, Corrosion and Tribological Properties of Al2O3 Films Grown by Anodization and MAO
by Aysenur KELE? DAYAUÇ, Özlem BARAN ACIMERT, Taha Ça?r? ?enocak
Abstract: Al-5083 alloys are used as a marine part due to resistance to harsh environment. However, mechanical and corrosion resistance to seawater is not sufficient. For this purpose, many different surface treatments, electrochemical coatings, etc. are used to increase the mechanical, wear and corrosion resistance of the surface of Al-5083. This works aims to enhance mechanical, corrosion and tribological properties of Al-5083. Therefore, in this study, the oxide surface was enlarged on the Al-5083 alloy by anodisation and MAO techniques. Three different current densities (25 mA/cm2, 50 mA/cm2 and 75 mA/cm2) were used in the anodisation process. In the MAO process, three different voltages (400 V, 420 V and 440 V) were used. SEM, XPS and AFM were used for microstructure after anodisation and MAO processes. Scratch and hardness test were used to determine mechanical properties, and pin-on-disc was used to determine tribological properties. Also, electrochemical test was used to evaluate the corrosion properties. According to studies compared, it has been observed that the anodisation technique in Al-5083 alloy is better than the MAO technique. Corrosion and mechanical strengths decreased with increasing voltage and current density in both techniques.
Keywords: anodisation; MAO; adhesion; corrosion; tribology.
Hydroxylated Derivatives of Methyl Oleate as Biobased Tribological Additives for Lubricants
by Boshui Chen, Chengli Tang, Chunyu Song, Mingjia Liao, Fangfang Jie
Abstract: Two hydroxy derivatives of methyl oleate (MeO), viz. methyl 9(10)-hydroxy stearate (MeHS) and methyl trans-9,10-dihydroxystearate (MeDHS), were prepared and characterised. The tribological properties of MeO, MeHS and MeDHS in lubricants were evaluated, and their triological mechanisms were analysed. Results showed that MeO, MeHS and MeDHS were efficient in improving tribological properties of paraffin oil and rapeseed oil, of which MeDHS was the best candidate. Furthermore, MeO, MeHS MeDHS provided more powerful lubricating abilities in paraffin oil than in rapeseed oil. The enhanced tribological properties of lubricants by MeO, MeHS or MeDHS were evidenced by increased maximum non-seizure loads, decreased wear scar diameters and friction coefficients. Finally, excellent lubricating abilities of MeDHS and MeHS were attributed to formation of a strengthened tribofilm due to adsorption of their molecules through strong bonding of the extra polar hydroxyl group(s), and the ester group of the parent methyl oleate, onto the metal surfaces.
Keywords: hydroxylated methyl oleate; tribological additive; tribological performance; paraffin oil; vegetable oil.
Nanoporous Surface Modification of 316L Support Materials by Electrochemical Dealloying
by Fatih Piskin
Abstract: The current study involves electroplating and dealloying processes applied sequentially to form a nanoporous Ni layer on 316L support material to produce a suitable substrate that enables thin film (< 1
Keywords: electroplating; electrochemical dealloying; porous supports; thin-film deposition.
A detailed study on the enhanced anti-corrosion properties of nano silicon dioxide additive influencing calcium modified zinc phosphate coating on mild steel
by Ruby Thomas, M.J. Umapathy, B. Vigneshwaran, J. John Alphin, A. Unock
Abstract: The influence of nano silicon dioxide additive on calcium modified zinc phosphated mild steel sample is researched in this paper. This study shows that the environment friendly nano additive provides a high porous, fine-grained and compact phosphate sealing by facilitating strong adsorption to the successive protective covering of mild steel. The formed coatings were characterised by scanning electron microscopy (SEM), energy dispersive X-ray (EDX), atomic force microscopy (AFM) and atomic absorption spectroscopy (AAS). The thermal stability of the coatings were analysed by thermo gravimetric analysis (TGA). The coating quality on the mild steel surface was examined by coating weight, porosity and adhesion tests. The corrosion studies were done using salt spray test and electrochemical impedance spectroscopy. The good dispersibility of the additive was observed on the coating with increased safety from erosion. The lower icorr value of 2.6477
Keywords: nano silicon dioxide; mild steel; calcium; zinc phosphate; coating; surface; corrosion.
Increasing the fatigue life and surface improvement of AL7075 alloy T6 by using ultrasonic ball burnishing Process
by Saber Saffar, Hamid Eslami
Abstract: Increasing the fatigue life and surface improvement of parts along with reducing production costs is very desirable for the industry. Ultrasonic-assisted (UA) burnishing has been acknowledged as a new approach to improve fatigue life. In this research, surface hardness, hardened surface depth, and fatigue life were investigated on tempered 7,075 aluminium alloy during UA burnishing. The experiments were carried out employing response surface methodology (RSM). In this regard, spindle speed, feed rate, Penetration depth, and ultrasonic power were considered as input variables of the process while vibration frequency was fixed at 20 kHz. Also, surface hardness and hardened surface depth were taken as responses to the process according to RSM. The UA burnishing showed a significant increase in the HV and hardened surface depth, as compared to the conventional burnishing process. In this respect, maximum HV and hardened surface depth were found to be 16% and 56% higher than those of the conventional burnishing process, respectively. Furthermore, fatigue life increased almost 32% when UA burnishing is employed rather than conventional burnishing.
Keywords: ball burnishing; high-power ultrasonic vibrations; surface hardness; response surface methodology; RSM; 7075 aluminium alloy.