International Journal of Surface Science and Engineering (12 papers in press)
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.
Friction Properties and Lubrication Mechanism of Self-Lubricating Composite Solid Lubricant on Laser Textured AISI 52100 Surface in Sliding Contact
by Xijun Hua, Julius Caesar Puoza, Peiyun Zhang, Jianguo Sun
Abstract: The frictional behaviour and lubrication mechanism of self-lubricating Gr-MoS2-PI-CNT composite were investigated experimentally, characterised by surface preparation method and texture density. The results indicate that the dimples filled with composite solid lubricant (sample TPL) exhibited the best lubrication mechanism with the lowest friction as compared to the smooth surface without lubrication (sample S), textured surface without lubrication (sample T), textured surface burnished with solid lubricant (sample TSL) and textured surface coated with solid lubricant block (sample TBL). The texture density of 41.7% exhibited good friction properties under both higher loads and speeds. The composite solid lubricant formed stable lubricant-peaks on each dimple the by slide extrusion accumulation mechanism with a gradient phenomenon along the sliding direction which improved the self-lubricating effect of the lubricant. The energy dispersive X-Ray spectroscopy (EDS) analysis indicates that the solid lubricant has been transferred from the micro-dimples to the space between dimples which improved lubrication.
Keywords: Composite solid lubricant; lubrication mechanism; laser surface texturing; texture density; friction; wear.
Study of rapid thermal treatment on the microstructural evolution and surface characteristics of the electrodeposited modify Zn/TiO2 Composite Coatings on AISI 1015 Steel
by O.S.I. Fayomi, A.A. Daniyan, L.E. Umoru, A.P.I. Popoola
Abstract: In this study, the effect of systematic homogenising annealing heat treatment on the morphology and hardness property of modified Zn-TiO2 nano composite coatings, coated via electrocodeposition process was investigated. The morphological characteristics of the composite coatings were characterized by scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS) and the hardness examination was carried out using dura Scan hardness tester. The result showed that the coatings systems were homogenised with refined microstructure after annealing at 250oC and 500oC. Three different intermetalic structures; Zeta, Delta and Gamma phase were observed after systematic homogenising annealing at 500oC. The hardness performance of the nanocomposite coatings was better after the annealing at 250oC for 5 hours and showed outstanding improvement after systematically annealed at 500oC.
Keywords: characterization; Homogenising; Annealing; Nanocomposite; Coating.
Mechanical and tribological properties of diamond-like carbon DLC and DLC:Si coatings deposited on stainless steel / WC-Co substrates
by Ricardo Santos, Sergio Camargo
Abstract: The mechanical and tribological properties of diamond-like carbon (DLC) and silicon-containing diamond-like carbon (DLC:Si) films with two different silicon contents (26 at.% and 45 at.%) deposited onto stainless steel / WC-Co substrates used for industrial applications as valve seats are investigated. DLC and DLC:Si films were deposited by radio frequency plasma enhanced chemical vapor deposition (rf-PECVD). The films were characterized by XPS and Raman spectroscopy, and their mechanical properties determined by nanoindentation. The coatings adhesion was evaluated by scratch tests and their tribological properties were investigated by linearly reciprocating ball-on-flat wear tests at two temperatures (T = 22 oC and 110 oC). DLC films presented the highest adhesion to the substrates, decreasing with the increase of silicon content. This is probably associated with the higher compressive stress and fracture toughness of DLC compared to DLC:Si films. The low silicon content DLC:Si films present higher friction coefficients and wear rates at 22 oC when compared to pure DLC, due to the continuous oxidation of the films by water molecules at the film surface during the tests, leading to the strong formation of oxide wear debris. However, at 110 oC the sticking coefficient of water molecules is much lower and so the friction coefficient and wear rate of the low silicon content DLC:Si films are strongly reduced due to the formation of a thin lubricating CSiO transfer layer. The high silicon content DLC:Si films, on the other hand, present a silicon carbide-like structure and, therefore, friction coefficient and wear rate are high because the mechanisms of friction and wear reduction of the DLC and the low silicon content DLC:Si films are not present.
Keywords: DLC; DLC:Si; WC-Co; diamond-like carbon; silicon carbide; thin films; coatings; mechanical properties; nanoindentation; tribology; friction coefficient; wear; wear rate; scratch test; adhesion; critical load.
Surface energy modification for coating adhesion improvement on polypropylene
by Elisa Medeiros, Ricardo Brandes, Hazim Al-qureshi, Derce Recouvreux
Abstract: Polypropylene (PP) has poor superficial properties making a pre-treatment before coating the paint film necessary. The pre-treatment related to surface improvement most widely used in the industry is the flame treatment due to its capacity to achieve the necessary level of surface energy. This work is to study the effect of the flame treatment in the adhesion increase for painting films applied on polypropylene substrates. Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Dyne Test Inks, contact angle, resistance to adhesion by engraving and washing were employed to evaluate the flame treatment. The morphological, chemical and physical analysis presented superficial modification, the formation of new functional groups and improvements on adhesion between substrates and paint film, respectively. These results proved the efficacy of the flame treatment in the increase of the surface energy and in the adherence of the coatings applied to the PP substrates.
Keywords: polypropylene; flame treatment; adherence; coating; painting.
Special Issue on: Developments in Tribology of Composite Materials
Wear and Friction Behavior of Aluminium metal Composite Reinforced with Graphite Particles
by Vipin K. Sharma, R. C. Singh, Rajiv Chaudhary
Abstract: Present paper discusses about the effect of graphite powder on the wear and friction properties of aluminium melt. The aluminium graphite composite was fabricated using the stir casting technique. Three different amounts of graphite particle with 2 wt.%, 4 wt.% and 6 wt.% are used for the fabrication of the composite. Pin on disc experiments were performed as per ASTM- G99 between aluminium graphite (Al-Gr) composite and mild steel tribopair. Scanning electron microscope images for the worn Al-Gr composite were obtained to study the wear of the composite. It is observed that graphite particles help in reducing the wear and friction coefficient of the aluminium
Keywords: composite; graphite; wear; friction; pin on disc; mild steel; stir casting.
Tribological properties of bronze filled PTFE under dry sliding conditions and aqueous environments (distilled water and sea water)
by Mohammad Jebran Khan, M.F. Wani, Rajat Gupta
Abstract: In the present study, the tribological behavior of 60 wt. % bronze filled PTFE sliding against AISI 420 stainless steel in ambient air, distilled water and sea water is investigated. The experiments were conducted on a pin on disc reciprocating tribometer at room temperature at a normal load of 10N. The bronze filled PTFE showed superior tribological performance in sea water as compared to distilled water and dry sliding. The lowest average coefficient of friction (0.045) and lowest specific wear rate (1.10
Keywords: friction; wear; PTFE; bronze; sea water.
THE EFFECT OF POLYMERIC BIOMATERIAL BINDER CONTENT ON CORROSION BEHAVIOUR, MAGNETIC AND TRIBOLOGICAL PROPERTIES OF THE MAGNETIC COMPOSITE BASED ON RE-M-B POWDER
by Dorota Klimecka-Tatar, Klaudia Radomska, Grażyna Pawłowska, Piotr Pawlik
Abstract: In the paper, the electrochemical characteristics of the RE-M-B magnetic powder bonded with polymeric biomaterial have been presented. It has been proven that the ratio of the binder to the magnetic powder effect on the surface roughness of the final magnetic material. With the increase of surface roughness also increases in the actual area of the metallic material contact with an aggressive environment - increased surface roughness promotes penetration of the corrosion medium into the material and consequently is favorable for the corrosive destruction. In the article the results of roughness measurements using a contact profilometer, vibratory magnetometer, microscopic analysis (2D) and corrosion tests in two corrosive environments: 0.5M solution of sulphate acidified to pH = 2 and Ringer's solution (pH = 6) have been presented. All tests had been carried out on magnetic composite based on Nd-(Fe,Co)-B magnetic powder bonded with polymeric biomaterial. As expected, it has been found that the increased in binder content has a beneficial effect on the growth of the corrosion resistance of the material.
Keywords: Keywords: magnetic composite; NdFeB magnets; bonded magnets; corrosion; surface roughness; magnetic properties.
A Comparative Study of Tribological and Mechanical Properties of Composite Polymer Coatings on Bearing Steel
by Anand Singh Rathaur, Jitendra Kumar Katiyar, Vinay Kumar Patel, Shubrajit Bhaumik, Anuj Kumar Sharma
Abstract: In this study, epoxy and SU-8 resin along with its composites was coated over bearing steel. The graphite, talc and base oil were used to fabricate the composites using spin-coater. The tribological and surface characterization tests were performed on both type of polymer and its composite using ball-on-disk setup, optical microscope, 3D optical profilometer, and goniometer, respectively. From the results, it can be seen that epoxy and its composites polymer showed lower coefficient of friction (~0.16), high wear resistance properties (>102 times), improvement in mechanical properties (elastic modulus and hardness) (~ 3-4 times) and better hydrophobic nature as compared to SU-8 polymer (~34%) and its composites. Furthermore, a neural network model was developed to determine the influential parameters on specific wear rate and coefficient of friction.
Keywords: Epoxy; SU-8; Bearing Steel; Neural network; Composite Coating.
Effect of Al2O3 nanoparticles on tribological behaviour of Mg-6Al alloy-based nanocomposites
by K. Bimla Mardi, Amit Rai Dixit, Ashis Mallick, A. Ramana Reddy
Abstract: This paper investigates the tribological properties of Mg-6Al alloy based nanocomposites reinforced with nano-size alumina nanoparticles. Dry sliding wear tests were performed in the pin-on-disc arrangement opposite to a D2 steel counterface under various sliding velocities 0.8-2.0 m/s with 10 N, 30 N and 60 N normal load at room temperatures. The variations in volumetric wear rate and friction coefficient with the sliding distances 300 m for different normal loads and sliding velocities were analyzed. The worn pins and wear debris were then examined to reveal its wear features using a ﬁeld emission scanning electron microscopy. The outcomes of the study reveal that there is a gradual decrease in wear rates with sliding speeds under all load conditions. The values of friction coefﬁcient for nanocomposites varies between 0.15 0.23 and reaches minimums at 2.0 m/s under 10 N and 1.8 m/s under 30 and 60 N load.
Keywords: Mg-based nanocomposites; wear rates; friction coefficient; wear mechanism.