International Journal of Surface Science and Engineering (18 papers in press)
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.
An efficient method for nonlinear characteristic analysis of fixed contact surface and interface in bolted joint and its application
by Chao Liu, Zongde Fang, Kun Shi, Li Song, Jinfu Du
Abstract: This paper proposes a modeling method for nonlinear characteristic analysis of bolted joint considering the combined effect of contact surface and the interface interaction. First, the discontinuous contact region of the bolted structure is regarded as a flat continuous medium based on the hypothesis of equivalent virtual material. Second, two user-defined elements are respectively developed to simulate the contact surface and flexible interface. Then, a typical example of bolted structure is simulated using the proposed method. The comparison of the simulation results and the measurements indicates that the method is valid for the nonlinear characteristic analysis of the joint. Moreover, the method also presents advantage in computational efficiency according to the comparison with the conventional FE model. Hence, the proposed method provides a feasible solution for bolted problem in practical engineering applications, such as the precision instrument design, ultra-precision position control and multi-body dynamics simulation of complex mechanical system.
Keywords: Contact surface; Flexible interface; Bolted joint; Nonlinear characteristic analysis; User-defined finite element.
SOLID PARTICLE EROSION STUDIES OF D-GUN SPRAYED CERMET COATINGS ON ASTM A36 STEEL
by Vineet Shibe, Vikas Chawla
Abstract: Erosion studies were performed in simulated coal-fired boiler conditions with a view to compare the erosion behavior of two different types of detonation gun (D-Gun) sprayed cermet coating powders, i.e. WC-12%Co and Cr3C2-25%NiCr on ASTM A36 steel and bare (uncoated) ASTM A36 steel. During the erosion studies weight loss, erosion rates in terms of volume loss (mm3/g) and measurement of erosion profiles were determined utilizing optical profilometer. All the two different types of D-Gun sprayed cermet coatings had successfully protected the ASTM A36 steel from erosive wear at impingement angles of 45
Keywords: air jet erosion testing; cermet coatings; detonation gun; volume erosion rate.
Observation and characterization of the surface hardness enhancement of the laser remelted NiCrBSi coating
by Jiangwei Liu, Song Chen, Yan Wang, Hu Li
Abstract: The hardness enhancement on the surface of the laser remelted NiCrBSi coating was observed and characterized by employing X-ray photoelectron microscopy and nanoindentation techniques. The result indicates that, under the line energy density of 80 J/mm, there is an agglomeration of the borides on the top 20 μm of the remelted coating that significantly enhanced the surface hardness as high as 1.5-fold stronger to 13 GPa than that of the main body of 8.5 GPa. Owing to the high concentration of the borides, the elemental distribution of the remelted surface has been modified significantly. In addition by varying the laser energy, the depth of the surface enhanced regions can be modified.
Keywords: laser remelting; NiCrBSi coating; surface hardness; tuneable depth.
Solid particle erosion studies on fibre composite with egg shell as filler materials
by M. Adam Khan, Mani Kandan, Ebenezer George, M. Uthayakumar, S. Thirumalai Kumaran
Abstract: The development on composite materials has a tremendous role in the place of metals and alloys for different engineering applications. On other hand the material selected for specific applications are prone to fail in bulk with surface defect and shear based on working conditions. Hence the challenges convince the researchers to modifying the materials with different reinforcement. In this paper glass fibre composite material was developed with and without fillers to investigate on solid particle erosion test rig. From the experiments, the surface wear and parameter influencing air jet erosion are studied in detail. The parameters involve are jet pressure, volume of erodent and exposed time at constant angle of impingement. Based on mass change erosive wear rate are empirically calculated. The surface topography of the sample are observed with electron microscopic analysis for superficial studies. Influence of process parameter are evaluated using 2k factorial design. It is confirmed that erodent behaviour and composite with filler material are dominating the erosive wear rate. The sample with polyester resin has an affinity to hold the abrasive particle as inclusion during striking of solid particle. Therefore the proposed model with natural filler in fibre reinforced surface has resistance toward erosion.
Keywords: erosion; composite; filler; wear; microscope.
Surface-modified substrates for the Langmuir Blodgett deposition of patterned ultra-thin and highly oriented collagen coatings
by Karina Ambrock, Bernd Grohe, Silvia Mittler
Abstract: As a pre-study for highly oriented collagen coatings on implants (with irregular surfaces and shapes), the Langmuir-Blodgett (LB) technology, a low-cost and straightforward approach, was pioneered. The effects of physicochemical (hydrophilic / hydrophobic) patterns and 3D-mechanical barriers present on substrate surfaces are studied in terms of the dynamics of collagen flow during LB film deposition and the formation of highly oriented coatings. Due to the large internal cohesion of collagen films only large 3D-obstacles deflect the flow of collagen and lead to film rupture, suggesting that objects (screw-threaded dental implants) with small topographic features should be easily and evenly coatable. Moreover, hydrophilic / hydrophobic / collagen patterned substrate surfaces were fabricated, by partly removing coated collagen. These substrates are outstanding for timely studies that need identical conditions but different surface properties side by side. Crystallization of barium oxalate was carried out as a proof-of-principle.
Keywords: Langmuir-Blodgett technology; collagen deposition; ultra-thin collagen coatings; highly oriented collagen; surface-modified substrates; hydrophobic substrates; hydrophilic substrates; 3d-obstacles; collagen film patterning; film-internal cohesion forces; adhesion forces; multifunctional substrate surfaces.
Mechanical and anti-wear properties of multi-module Cr/CrN coatings
by Łukasz Szparaga, Katarzyna Mydłowska, Adam Gilewicz, Jerzy Ratajski
Abstract: The objects of investigations were Cr/CrN multi-module coatings deposited using a cathodic arc evaporation method (CAPVD) on HS6-5-2C steel used as a substrates. Analyzed coatings possess 7 Cr/CrN modules of fixed thickness each, with various thicknesses of Cr and CrN layers. Aiming for the evaluation of mechanical properties of tested multi-module Cr/CrN coatings, its hardness and Young's modulus were measured, on the basis of which were determined values of H/E and H3/E2 ratios. Coatings wear and friction coefficient were measured in so called ball-on-disc test. The adhesion of the coatings was evaluated using scratch tester and was shown that main mechanism of adhesive damage of all tested coatings at higher loads are buckle spallations. All tested coatings are also characterized by good adhesion to the substrate, which is evidenced by the fact that cracked coating remains inside the scratch track. Basing on the analysis of obtained experimental results it was confirmed and explicitly shown that the thickness of the individual layers of Cr and CrN in the multi-module coating significantly affects its critical loads (in scratch test), fracture toughness and wear rate.
Keywords: thin hard coatings; PVD; anti-wear coatings; multi-layer coatings; nanoindentation; adhesion, scratch test; fracture toughness; ball-on-disc test; hard chromium replacement
Pull-off Strength and Abrasion Resistance of Anti-corrosive Polymer and Composite Coatings
by Anna Dmitruk, Paulina Mayer, Joanna Pach
Abstract: The paper aims at presenting the results of pull-off strength and abrasion resistance tests for anti-corrosive coatings on steel substrates. It contains the measured data on the thickness of manufactured coatings in the function of the applied amount of abrasive material. Three polymeric coatings were subjected for testing: chlorinated rubber, oil-phthalic and alkyd. The analogous studies were repeated for composite coatings with alumina α-Al2O3 filler and subsequently also for the aged (72 h, -19°C) systems. For the pull-off tests the damage analysis of samples after failure was performed. The highest pull-off strength’s values for the produced coatings were obtained for the alkyd one. Concerning the abrasion resistance it can be stated that the addition of a filler significantly improves the system’s durability, while the aging process causes its deterioration.
Keywords: anti-corrosive; coatings; abrasion resistance; pull-off strength; composites; polymers
Special Issue on: Developments in Tribology of Composite Materials
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.
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.
Effect of mechanical milling of fly ash on friction and wear response of brake friction composites
by VISHAL AHLAWAT, SANJAY KAJAL, Anuradha Parinam
Abstract: The effect of milled fly ash on the tribological response of brake friction composites is studied. Two specimens were developed using Raw Fly Ash (RFA) and Milled Fly Ash (MFA) and tested for the friction and wear performance at different loads (50-100 N) with sliding velocities varying from 1.7 to 3.3 m/s. It was observed that the spherically shaped RFA particles transformed into rough and uneven shaped particles after ball milling. The particle size range was found to be 22.05-206.19
Keywords: ball milling; raw and milled fly ash; brake friction composites; friction and wear.
Tribological Study on Hybrid Reinforced Aluminium Based Metal Matrix Composites
by Panneerselvam T, Kandavel T. K., Arun K.S., Dineshkumar V.
Abstract: The demand for Aluminium based metal matrix composites is growing in aerospace and automotive industries because of its good corrosion resistance and high strength to weight ratio. The present work focuses on tribological characteristics of stir cast hybrid composites synthesized with AA6063, Boron carbide and Zirconium silicate. Composite specimens were prepared with three percentages of reinforcement materials by weight, i.e., 3%, 6% and 9%, and the matrix material at 88%. Tribological experiments were conducted on the specimens with a pin-on-disc tribometer, using L9 orthogonal array experiments with various parameters including load, speed and time. SEM and optical micrographs were employed to investigate the mode of wear mechanism on worn out surfaces of the specimens. The investigation has confirmed that the hybrid composite synthesized with 3% boron carbide and 9% zirconium silicate has shown an enhanced wear resistance with a lower coefficient of friction as compared to the other composites.
Keywords: Aluminium metal matrix; Boron carbide; Zirconium silicate; Dry sliding wear; Tribology.
A comparative study for the leverage of micro and nano SiC fillers on thermo-mechanical and erosion wear peculiarity of woven glass fiber based vinyl ester composites
by ANANT KRISHAN PUN, Siddhartha Vashishtha
Abstract: The impact of micro and nano silicon carbide (SiC) filler addition on thermo-mechanical behavior and erosion wear is investigated. Wovenglass-vinyl ester composites are developed, filled with 5wt.% and 10wt.% of micro and nano SiC fillers, respectively. Filler less composites are also prepared for comparative study. Thermo-mechanical characterization of composites is done as per ASTM standards. Erosion wear test is performed on composites for various angles of impact (30
Keywords: Erosion wear; Woven glass fiber; Micro and nano size SiC fillers; Vinyl ester resin; Taguchi design of experiment; VIKOR method.
Characterization of electroless Ni-P and electroless composite coatings Ni-P/NiPTFE
by Zdravka Karaguiozova
Abstract: The present study is based on the investigation and characterization of electroless nickel (Ni-P) and composite nickel PTFE (Ni-P/Ni-PTFE) coatings. The plating bath composition and the technological regime for production of electroless nickel coatings are proposed. An easily controlled, ecofriendly and simple in operating system technology is developed applying electroless method EFTTOM-NICKEL. PTFE particles are added to the plating bath in suspension. The investigation on the possibility to obtain a stable PTFE suspension is implemented. One layer Ni-P coatings and double layer Ni-P/Ni-PTFE coatings are plated on steel samples. The volume of incorporation of PTFE is measured depending on the temperature, pH, etc. Microhardnes, wear resistance tests and dynamic friction coefficient are measured and comparison the results are performed for Ni-P and Ni-P/Ni-PTFE coatings with different vol. % of incorporation of the PTFE particles.
Keywords: electroless coating; composite nickel coating; PTFE particles; wear resistance; dynamic friction coefficient.