International Journal of Surface Science and Engineering (13 papers in press)
Effect of microwave power on morphology of AgO thin film grown using microwave plasma CVD
by Akhalakur Rahman Ansari, Mohd. Imran, I.S. Yahia, M. Sh. Abdel-Wahab, Ahmed Alshahrie, Afzal Husain Khan, Chandan Sharma
Abstract: In this study, pure silver (Ag) thin film of 8 nm was deposited onto glass substrate by using Radio Frequency (RF) sputtering technique and was then exposed to microwave assisted oxygen plasma generated by microwave plasma CVD. The oxidation of Ag into AgO thin film was studied using varying microwave power. The influence of microwave power on morphology and size of oxide film was investigated. The crystal structure, crystal size, chemical composition, morphologies and optical properties of oxidized silver thin film (AgO) is characterized by using X- ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), Raman spectroscopy and UV-Vis spectroscopy. Morphological characterization of these films reveals a systematic change from metallic silver (Ag) to silver oxide (AgO). The size of AgO thin film was calculated by using Scherrer equation and was observed as 11 nm, 12 nm and 13.5 nm at 400 W, 800 W and 1200 W respectively. A considerable change in UV-Vis spectra was observed with increase in annealing temperature.
Keywords: AgO; Thin Film; oxygen plasma; microwave CVD.
Effects of pH on CdO films deposited onto ITO coated glass substrates by electrodeposition
by Baris Altiokka, Ayca Kiyak Yildirim
Abstract: Thin films of CdO were deposited onto indium tin oxide (ITO) coated glass substrates using electrodeposition method. The pH of the final solutions was adjusted from 4 to 8 and effects of pH on the films were investigated. The maximum film thickness was reached at pH 5 and XRD studies showed that this film had relatively high peak intensities. Optical studies showed that band gap varies between 2.04 and 2.41 eV and depend on pH. The surface morphologies were analysed by SEM images and they revealed that films were deposited compact and there were no voids, cracks or pinholes.
Keywords: CdO; Thin Films; electrodeposition; pH.
In-situ formation, anti-Corrosion and Hardness values of Ti-6Al-4V Biomaterial with Niobium via Laser deposition.
by Phume L, Popoola Api, VICTOR AIGBODION, Pityana S
Abstract: Ti-6Al-4V alloy biomaterials have low hardness, wear resistance, high corrosion rate and toxicity as results of release of aluminium and vanadium ions that led to the premature failure of the implant. In order to overcome some of these problem that lead to laser cladding of Ti-6Al-4V alloy with Niobium. Three laser parameters (laser power, beam diameter and laser scan speed) were used to ascertain the proper operating condition for this laser process. RofinNd: YAG laser was used in the laser cladding. The electrochemical study was conducted using Hanks buffered salt solution an environment similar to the human body. The optimum improvement in corrosion resistance resulted to 81.79% when compared with substrate. It has been established that operating parameter for laser cladding of Nb on Ti6Al4V were obtained at: laser power(1000W), beam diameter (1mm) and scan speed (0.3m/min).
Keywords: Keywords: Niobium; Laser parameters; Ti-6Al-4V alloy; Microstructure and Corrosion.
Superficial alterations in the generation of a 3D surface. The case of machining by turning. Application of Principal Component Analysis to the study of the various factors involved
by Fernando Ancio, Antonio J. Gámez, Mariano Marcos
Abstract: Surface quality is an essential requisite in the manufacturing industry. In order to perform an in-depth study into the mechanisms that govern the formation of this surface, all factors involved in the machining process must be ascertained. The resulting surface after turning (real surface) is studied as the superposition of multiple surfaces. A first surface, (tool surface), is generated from the geometry of the tool and machining parameters. A second surface (vibration surface) is generated from the vibration of the tool. Finally, a third surface (other-factors surface) is taken as the joint result of fracture of material, elastic recoveries, plastic deformations, deposits and/or adhesions of material and/or tool wear. The comparison of these four surfaces enables this objective to be reached. A new parameter denominated dispersion, is defined. Principal Component Analysis (PCA) is used in the definition of this parameter.
Keywords: Surface quality; Manufacturing industry; Turning; Roughness; Vibration; Fracture of material; Elastic recoveries; Plastic deformations; Deposits and/or adhesions of material; Tool wear Principal Component Analysis (PCA); Characterisation of surfaces.
Electrochemical Studies and Surface Analysis of Laser Deposited Zn-Al-Sn Coatings on AISI 1015 Steel.
by Olawale S. Fatoba, Abimbola P. I. Popoola, Victor S. Aigbodion
Abstract: Surface hardening of mild steel with Zn-Sn bath is characterized by the traditional phases, whereas presence of Aluminium leads to coatings constitute by phase in the inner layers, and by an outer layer made of three phases and intermetallic phases which made the materials to be brittle. Enhancement in properties of Zn-Al-Sn coating led to the investigation of Zn-Al-Sn coating on mild steel by laser alloying technique. Composition of 25%Zn-50%Al-25%Sn and 30%Zn-40%Al-20%Sn with laser power of 750 W, scanning speed of 0.6 and 0.8 m/min were used in this research. Standard techniques were used for the characterization of the laser samples and 0.5 M H2SO4 was used for the electrochemical test. The results showed that all the properties were improved by increasing the Al content from 40 to 50%. The optimum properties were obtained at 25%Zn-50%Al-25%Sn at laser power of 750 W and speed of 0.8 m/min. The optimum composition significantly improved the corrosion resistance of Zn-Al-Sn coatings in 0.5 M H2SO4 solutions and 2.2-times the hardness of the substrate was also achieved. It has been established that laser alloying of mild steel with Zn-Al-Sn coatings is promising for improving the surface hardness values and corrosion resistance.
Keywords: Keywords: AISI 1015 steel; Zn-Al-Sn Coating; Hardness; Electrochemical properties; intermetallics.
Tribological Performance of DLC/DLC and Steel/DLC Contacts in The Presence of Additivated Oil
by Abdul Mannan, M.F.M. Sabri, M.A. Kalam, H.H. Masjuki
Abstract: In this study, the tribological properties of ta-C DLC were largely influenced by the counter surfaces and additives. The DLC/DLC contact showed approximately 60% lower wear when tested with additivated oil compared to that of base oil and this result was 66% in Steel/DLC contact. Friction coefficient in DLC/DLC contact was lower than in Steel/DLC contact under both oils. But however, both contacts showed slightly higher friction coefficient under additivated oil compared to that of base oil. In Steel/DLC, the thermo-chemical reaction between carbon and iron and/or the fusion of the transferred particles were prevented by additives which were present under base oil. The fracture found on DLC surface in Steel/DLC contact under additivated oil indicates that the tribolayer formed on the steel surface would be of brittle nature. The passivation of surfaces in DLC/DLC contact by additives prevented the damage which was observed under base oil.
Keywords: DLC Coatings; Vegetable Oil; Four Ball Tribo-testing; Anti-wear Additive; Fiction and Wear.
Copper Electrodeposition on Silicon Electrodes
by Frederico Lima, Ulrich Mescheder, Claas Müller, Holger Reinecke
Abstract: A two-step process is reported for the electrochemical deposition of copper layers on n-type silicon substrates using an acidic copper sulphate solution without addition of additives and neither light assistance. Metal layers were generated on electrodes with different crystal orientations. The process consists of a combination of two very common techniques: chronoamperometry and pulse plating. The former technique is applied to obtain an instantaneous nucleation on the working electrode. Therefore, a large amount of metal nuclei is formed on the substrate before the pulse technique starts. The latter is, then, used to grow the particles previously generated and form a homogeneous metal layer with full coverage onto the semiconductor electrodes. The potential magnitudes are carefully chosen in line with energy levels observed at the semiconductor-electrolyte interface and were also calculated in this work.
Keywords: seedless electroplating; silicon coating; semiconductor-electrolyte interface; pulse plating; copper plating.
Variation of surface roughness, micro-hardness and friction behaviour during sheet-metal forming
by Tomasz Trzepiecinski, Wojciech Bochnowski, Lucjan Witek
Abstract: The aim of the research described in this paper is to analyse the evolution of the main surface parameters values and friction coefficient value due to the sheet deformation. Frictional properties of the deep-drawing quality steel sheets were investigated using the strip drawing test under both dry and lubricated conditions. An increase in the plastic deformation of sheets in the range of true strain between 0 to 0.28 caused an increase in the value of amplitude roughness parameters Ra, Rp, Rt, measured along the rolling direction of the sheet metal and perpendicular to this direction. The character of frictional phenomena of the deformed sheets is a complex function of sheet directional topography, formed by pre-straining and strain-hardening phenomena. It was also found that owing to the strain-hardening phenomenon the micro-hardness of the sheet increased with the sheet deformation. However, this relation was near linear.
Keywords: friction; microhardness; sheet metal forming; strip drawing test; surface roughness; surface topography.
White Light Interferometry and MountainsMap
by Iqbal Shareef, Omar Castiblanco
Abstract: Ever since the coining of the word "Tribology" by Peter Jost in 1966, and the characterization of surface measurement by means of random process analysis by J. Peklinik in 1968, the characterization of engineered surfaces has undergone metamorphic changes. This paper deals with two case studies demonstrating the combined use of White Light Interferometry and MountainsMap
Keywords: Surface roughness; White Light Interferometry; MountainsMap®; Static Load Capacity; Ball Bearing Indentations; Robust design; Signal-to-noise (S/N) ratio.
Microstructure and wear behavior of laser hardened SAE 4130 steels
by Raphael Bambirra, Rafael Siqueira, Milton Lima
Abstract: Low alloy SAE 4130 steel had been laser hardened for the microstructure, hardness and wear characterization. An almost fully martensitic layer, with case depth of approximately 0.5 mm, was obtained by defocusing a fiber laser by 50 mm. The best results were produced by 600 W laser power, a beam defocusing of 50 mm and a speed of 8 or 10 mm/s, where a maximum hardness of 390 HV was obtained compared to 220 HV of the base material. The laser treated surfaces presented a combination of oxides and wear behavior distinctly superior to the bare surface. The coefficients of friction (COF) of the lasered surfaces were approximately half of the bare condition. The average COF maximum value and standard deviation was superior for the bare compared to the lasered conditions. Finally, the wear rate is three times larger in the unlasered sample compared to the laser treated ones.
Keywords: laser; laser surface processing; low-alloy steels; wear.
Experimental Study on the Tribological Properties of CuO based Biodegradable Nanolubricants For Machine Tool Slideways
by Nallasamy P, Saravanakumar N, Rishwin Kumar R.K, Gukan Rajaram
Abstract: Bio-lubricants are biodegradable and nontoxic. Biobased lubricants are an attractive alternative to conventional mineral oil based lubricants. This study deals with the tribological investigation of biodegradable nanolubricants which could be applied in machine tool slideways. The nanoparticle used was Copper oxide (CuO) and the biodegradable oils used were coconut oil, sesame oil, olive oil, sunflower oil and soybean oil. The nanolubricants were prepared by adding 0.1% wt of CuO nanoparticles in each biodegradable base oil. Experiments were conducted on a pin on block type Reciprocating Friction Monitor and Four Ball Tester. Friction, stick-slip and wear characteristics were analysed. The test results showed that the addition of CuO nanoparticles in biodegradable oils improve friction reduction and antiwear properties. The mechanism of friction reduction is found to be the formation of tribofilm through deposition of CuO nanoparticles on the wear surfaces. Field testing was conducted for the best nanolubricants.
Keywords: biodegradable oil; nanolubricant; CuO nanoparticle; reciprocating friction monitor; four ball tester; stick slip friction; antifriction; antiwear.
Theoretical models for surface roughness in turning considering inclination and rake angles
by Aun Naa Sung, Mani Maran Ratnam, Wei Ping Loh
Abstract: New analytical four-parameter models for surface roughness are proposed based on the feed rate, nose radius as well as the inclination and rake angles. These models were derived to determine the maximum peak-to-valley roughness Rt and arithmetic average roughness Ra using homogeneous transformation matrices and are verified by digital simulation. The model for Rt was used to study two sequential effects of introducing the inclination and rake angles. The Rt and Ra values obtained from the four-parameter models and the existing two-parameter models, based on nose radius and feed rate, were compared. The comparison shows maximum percentage differences of 8.2% and 11.0% in Rt and Ra, respectively. The results demonstrate that the inclination and rake angles can influence the surface roughness by affecting the tool-work piece contact geometry. The proposed four-parameter model can be employed for a more accurate theoretical surface roughness evaluation compared to the existing two-parameter models.
Keywords: roughness; turning; inclination angle; rake angle.
Influence of graphene and multi-walled carbon nanotube additives on tribological behavior of lubricants
by Rabesh Kumar Singh, Amit Rai Dixit, Anuj Kumar Sharma, Arun Kumar Tiwari, Vimal Mandal, Alokesh Pramanik
Abstract: In the present study, the tribological performance of water-based emulsion (lubricant) was investigated by blending carbon fillers such as graphene nanoplatelets and multiwall carbon nanotubes using pin-on-disc tribometer. It was noticed that addition of GnP and MWCNT in water-based emulsion (conventional lubricant) increases the thermal conductivity and viscosity as compared to conventional lubricants. The nanolubricants were supplied with minimum quantity lubrication (MQL) technique at a constant flow rate and pressure in the sliding zone. The addition of 0.8 wt.% concentration of GnP showed 58.39% reduction in coefficient of friction and 61.80% reduction in wear depth compared to the conventional lubricant. Similarly, for 0.8 wt.% concentration of MWCNT showed 26.27% reduction in coefficient of friction and 47.35% reduction in wear depth compared to the conventional lubricant. The sliding surface micrographs were also investigated to explain the synergistic effect of nanoparticles.
Keywords: Nanolubricants; Wear depth; Coefficient of friction; MWCNT; GnP