Investigation of Tribological Behavior of PTFE Composites Reinforced with Bronze Particles by Taguchi Method

Purpose This study aims to investigate and compare the tribological behavior of two high-performance polymers, ultra-high-molecular weight polyethylene (UHMWPE) and polyetheretherketone (PEEK), under dry sliding conditions against steel and various polyetherimide (PEI)-based polymer counterfaces. Design/methodology/approach Pin-on-disk wear tests were carried out using the UHMWPE and PEEK pins sliding against four different counterfaces of general purposed (GP)-PEI, wear resistant (WR)-PEI, glass fiber-reinforced PEI (PEI + 20% GFR) and AISI 304 L stainless steel. The experiments were conducted under normal loads of 20, 40 and 60 N at a constant sliding speed and distance. The coefficient of friction (COF), specific wear rate (SWR) and dominant wear mechanisms were evaluated based on the experimental measurements and optical microscopy observations. Findings The UHMWPE consistently exhibited lower COF and specific wear rate values than those of the PEEK, under all test conditions. Its best tribological performance was achieved at a load of 60 N against the GP-PEI counterface, yielding the COF and SWR values of 0.0728 and 7.96 × 10–15 m²/N, respectively. For the PEEK, the optimum values of the COF and SWR were obtained as 0.1856 and 8.79 × 10–15 m²/N, respectively also against the GP-PEI. The superior performance of the UHMWPE was mainly attributed to its self-lubricating behavior and the formation of a stable transfer film. However, the PEEK exhibited higher and more unstable friction behavior, particularly when sliding against the PEI + 20% GFR and steel counterfaces. Originality/value Unlike most previous studies focusing primarily on the metal–polymer tribological pairs, this study provides a comprehensive comparative evaluation of polymer–polymer and polymer–metal interfaces. The findings demonstrate that the UHMWPE outperforms the PEEK in the dry sliding applications and offer valuable insights for the rational selection of tribo-pairs in the engineering applications.

Friction and wear behavior of SiAlON were investigated under reciprocating sliding and fretting conditions. A metallic ball on SiAION disc configuration was used for all tests. In the case of reciprocating sliding, highest friction coefficient (0.48) was observed under a normal load of (400 N). Lowest friction coefficient (0.05) was observed using SAE 40 with EP additive as lubricant. In case of fretting, highest friction coefficient (0.475) was observed under a normal load of 60 N. Wear of all SiAIONSs increased with the increase in sliding distance and decreased with the increase in sliding velocity. Wear was found independent of normal load. In case of counter face steel, wear increased with the increase in sliding distance and normal load, and was found independent of sliding velocity. Lowest specific wear rate (7.4x 10 -5 mm 3 N -1 m -1 ) was observed for SiAION and highest specific wear rate (9.3x 10 -5 mm 3 N -1 m -1 ) was observed for steel in reciprocating sliding conditions. In case of fretting, wear increased with the increase in fretting time and normal load and decreased with the increase in fretting amplitude. Transition from high to low wear occurred at fretting amplitude of (100 - 150 μm). High specific wear rate of SiAION and steel was observed in fretting as compared to reciprocating sliding. Microscopic studies proved useful for understanding wear mechanism.

Tribological Characterization of Dental Restorative Materials

This paper investigates the dry sliding wear behaviour of squeeze cast Al-Cu-Mg reinforced with nanographite metal matrix composites. The experimental study employed the Taguchi method. The Taguchi method plays a significant role in analyzing aluminium matrix composite sliding tribological behaviour. Specifically, this method was found to be efficient, systematic, and simple relative to the optimization of wear and friction test parameters such as load (10, 20, and 30), velocity (0.75, 1.5, and 2.25 m/s), and nanographite (1, 3, and 5 wt%). The optimization and results were compared with the artificial neural network. An orthogonal array L27 was employed for the experimental design. Analysis of variance was carried out to understand the impact of individual factors and interactions on the specific wear rate and the coefficient of friction. The wear mechanism, surface morphologies, and composition of the composites have been investigated using scanning electron microscopy with energy-dispersive X-ray spectroscopy. Results indicated that wt% addition of nanographite and increase of sliding speed led to a decrease in the coefficient of friction and wear rate of tested composites. Furthermore, individual parameter interactions revealed a smaller impact. The interactions involved wt% of nano-Gr and sliding speed, sliding speed and normal load, and wt% of nano-Gr and normal load. This inference was informed by the similarity between the results obtained ANN, ANOVA, and the experimental data.

Study of Friction and Wear of ABS/Zno Polymer Composite Using Taguchi Technique

A single high-nitrogen face-centered-cubic (f.c.c.) phase (γN) layer formed on the plasma source nitrided AISI 316 austenitic stainless steel at a nitriding temperature of 450 °C for a nitriding time of 6 h. An approximately 17 μm-thick γN layer has a peak nitrogen concentration of about 20 at. %. Tribological properties of the γN phase layer on a ball-on-disk tribometer against an Si3N4 ceramic counterface under a normal load of 2 and 6 N with a sliding speed of 0.15 to 0.29 m/s were investigated by friction coefficient and specific wear rate measurement. Worn surface morphology and wear debris were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. The microhardness of the γN phase layer on the nitrided stainless steel was measured as about 15.1 GPa. The change in the friction coefficient of the γN phase layer on the stainless steel was dependent on the applied normal load, which was associated with that in the specific wear rate. Under a lower normal load of 2 N, the lower specific wear rate of the γN phase layer with a sliding speed of 0.15 m/s was obtained as 2.8 × 10−6 mm3/N m with a friction coefficient of 0.60. Under a higher normal load of 6 N, the lower specific wear rate with a sliding speed of 0.29 m/s was 7.9 × 10−6 mm3/N m with a friction coefficient of 0.80. When the applied load increased from 2 to 6 N, a transition of the wear mechanisms from oxidative to abrasive wear was found, which was derived from the oxidation reaction and the h.c.p. martensite phase transformation of the γN phase during the wear tests, respectively.

In this study, novel Al6061–SiC nanocomposites and Al6061–SiC–Gr hybrid nanocomposites were fabricated by ultrasonic cavitation method by adding silicon carbide (SiC) of 0.8 and 1.6% and graphite (Gr) of 0.5 and 1.0% by weight basis for each casting. A Three-level Box–Behnken design of experiment was developed using response surface methodology. Dry sliding wear tests were performed as per the experimental design using a pin-on disc set-up at room temperature. Analysis of variance (ANOVA) was applied to investigate the influence of process parameters viz., load, sliding distance, wt% reinforcement and their interactions on specific wear rate and coefficient of friction. Further, a mathematical model was formulated by applying response surface method in order to estimate the tribology characteristics such as wear and COF of the hybrid nanocomposites. The specific wear rate and coefficient of friction were significantly influenced by % of SiC followed by % of Gr, load and sliding distance. The wear test parameters were optimized for minimizing specific wear rate and COF using desirability function approach. A set of optimum parameter of combination for AMMNC was identified as: SiC 1.36wt%; Gr 0.63 wt%; load 35.65 N and sliding distance 2848 m with specific wear rate of 0.517 g/N-m; coefficient of friction 0.181. The AFM image of Al6061–1.36SiC–0.63Gr hybrid nanocomposite at optimized condition confirmed the improvement in the wear surface smoothness of the hybrid nanocomposite compared to Al6061–SiC nanocomposites.

An aluminum Al-0.8Al2O3 and Al − 1.6Al2O3 nanocomposite was prepared by a novel ultrasonic assisted stir casting method. A three-level Box-Behnken design of experiment was developed using response surface methodology. Dry sliding wear tests were performed as per the experimental design using a pin-on disc setup at room temperature. Analysis of variance (ANOVA) was applied to investigate the influence of process parameters, viz., wt.% reinforcement, load and sliding distance, and their interactions on specific wear rate and coefficient of friction. Further, a mathematical model has been formulated by applying response surface method in order to estimate the tribology characteristics such as wear and COF of the nanocomposites. The specific wear rate and coefficient of friction are significantly influenced by % of Al2O3 and load. The wear test parameters were optimized for minimizing specific wear rate and COF using desirability function approach. A set of optimum parameters of combination for AMMNC was identified as Al2O3–1.1 wt.%; load, 34 N and sliding distance, 2931 m with specific wear rate, 1.06 g/N-m; and coefficient of friction, 0.305. The AFM image of Al6061–1.1Al2O3 nanocomposite at optimized condition confirms the improvement in the wear surface smoothness of the nanocomposite compared to Al6061.

In this investigation, the sliding wear analysis of Epoxy/MWCNT, Epoxy/Nanoclay, and Epoxy/MWCNT‐Nanoclay composites have been determined. Different wt.% of MWCNT and Nanoclay is embedded into epoxy resin for the formulation of Epoxy/MWCNT, Epoxy/Nanoclay, and Epoxy/MWCNT/Nanoclay composite with the use of homogenizer and ultrasonic Probe sonicator to disperse nanoparticle completely into the resin. Four different controlling factors, i.e., filler content, sliding distance, RPM, and normal load were considered for sliding wear analysis and relation between these factors. The output (specific wear rate and coefficient of friction) were also generated through Taguchi design of experiments (DoE) and analysis of variance (ANoVA) methods for the validation. Controlling variable like normal load (10, 20, 30, and 40 N), sliding distance (1000, 1500, 2000, and 2500 m), and RPM (300, 400, 500, and 600) had selected to analyze the wear and friction. The results had shown that the specific wear rate and coefficient of friction were lower with adding of MWCNT and Nanoclay into the epoxy resin. Epoxy/MWCNT‐Nanoclay had shown lower weight loss as compare to Epoxy/Nanoclay and Epoxy/MWCNT composites. The optimum control variables were investigated, and found that Epoxy/MWCNT‐Nanoclay, having 0.5 wt.% of MWCNT and 4 wt.% of nanoclay had shown lower specific wear rate and low coefficient of friction.

The aluminium hybrid composite processed powder metallurgy and wear behaviour was experimentally investigated on aluminium with 0.5 wt% nano-BN reinforcement combined with nano-TiO2 weight per cent reinforcement of 0.3, 0.5 and 0.7% at different sliding velocities ranging from 1.5 to 2.5 m/s and different normal loads ranging from 5 to 15 N. The effect of specific wear rate and coefficient of friction was optimized using D-optimal method. The results predicted by the developed model are concurring well within the measured values. The correlation coefficient of model, regarding the specific wear rate and coefficient of friction, was about 0.9891 and 0.9805, respectively, with conform the degree of accuracy of the mathematical model. The optimal condition attained the minimum specific wear rate and coefficient of friction at sliding velocity 1.5 m/s at normal load 14.36 N for Al + 0.5 wt% BN + TiO2 0.3 wt% composite. The optimal predicted value of specific wear rate was 0.00043e-9 mm3/Nm and coefficient of friction 0.66, respectively.

Tribological behaviour of uni-directionally aligned silicon nitride against steel

The imp roved performance of poly mers and their co mposites in industries and many other applications by the addition of part iculate fillers has shown great advantages and so has lately been the subject of considerable interest. In this paper, mechanical and tribological behavior of particu late fillers CaCO3 and CaSO4 filled v inyl ester co mposites have been presented. Wear tests were carried out in dry sliding conditions on a pin-on-disc friction and wear test rig. (DUCOM) at roo m temperature under slid ing velocity (1.57, 2.62 and 3.67 m/sec.), normal load (20, 40 and 60 N), filler content (0, 10 and 20 wt.%) and sliding d istance (1000, 3000 and 5000 m). The plans of experiments is based on the Taguchi technique, was performed to acquire data in a controlled way. An orthogonal array and analysis of variance (A NOVA ) were applied to investigate the influence of process parameters on the coefficient of friction and sliding wear behaviour of these composites. The coefficient of frict ion and specific wear rate were significantly influenced with increase in both the filler content. The results show that for pure vinyl ester the coefficient of frict ion and specific wear rate increases with the increase of normal load, sliding velocity and sliding d istance. The coefficient of friction and specific wear rate for CaCO3 filler decreases with the increase of filler content. But, for filler CaSO4 the coefficient of frict ion and specific wear rate decreases at 10 wt.% and then increases at 20 wt.%. It is believed that a thin film formed on stainless steel counterface was seems to be effective in improving the tribolog ical characteristics. The worn surfaces examined through SEM to elucidate the mechanis m of friction and wear behaviour.

In this study, the tribological performance of polyamide‐6 (PA‐6), polypropylene (PP), polyamide‐6/polypropylene (PA‐6/PP) polymer blend, and nanoclay reinforced polyamide‐6/polypropylene composite are investigated. Nanoclay reinforced polymer composite is produced by melt compounding using co‐rotating twin screw extruder followed by injection moulding. Tribological studies are carried out using a pin‐on‐stainless steel disc configuration under dry sliding conditions. Tribological tests are carried out at sliding speed of 0.5 m s−1 and applied load values of 25, 50,100, 150 N. The friction coefficient and specific wear rate values are obtained and evaluated. The results show that the addition of nanoclay into the PA‐6/PP polymer blend reduced their coefficient of friction and specific wear rate values. The lowest coefficient of friction and specific wear rate values are for nanoclay reinforced PA‐6/PP blend. The highest coefficient of friction and specific wear rate values are for PA‐6 polymer.

Dry sliding wear characteristics of commercially available poly-ether-imide (PEI)+20% ( glass fiber reinforced)GFR and polysulfone (PSU)+20% GFR polymer composite in use in electrical engineering applications were investigated using a pin―on―disc rig. Pin materials are (PEI)+20% GFR and PSU+20% GFR polymer composite. Disc materials are AISI 4140 steel and PA 46+30%GFR polymer composite. Wear tests were carried out at 0.5 and 1.0 m/sec sliding speeds and 20, 40 and 60N load values and under atmospheric conditions of temperature and humidity. Different combinations of rubbing surfaces were examined and the dynamic friction coefficient and specific wear rate values were obtained and compared. For all material combinations, the coefficient of friction shows little sensitivity to sliding speed and applied load values and large sensitivity to material combinations. For specific wear rate, PEI composite has shown little sensitivity to change in load, speed and materials combination while PSU composite shown large sensitivity to the change in load and material combinations. The friction coefficient of PEI+20%GFR and PSU+20GFR rubbing against AISI 4140 steel disc is a round 0.3 and is about 0.12 as rubbing against PA 46+30%GFR. The specific wear rate for PEI and PSU composites are in the order.of 10 -15 to 10 -14mm3 /N.m. The wear mechanisms are a combination of adhesive and abrasive wear.

Sliding wear performance of 20% mica-filled polyamide 6 (PA6 + 20% mica) and 20% short glass fibre-reinforced polysulphone (PSU + 20 GFR) polymer composites used in electrical applications were investigated using a pin-on-disc wear test apparatus. Two different disc materials were used in this study. These are AISI 316 L stainless steel and 30% glass fibre-reinforced polyphenylenesulphide (PPS + 30%GFR) polymer composite. Wear test was carried out at 10, 20 and 30 N applied load values and 0·5 m/s sliding speed and at ambient temperature and humidity. Different combinations of rubbing surfaces were examined and friction coefficient and specific wear rate values were obtained and compared. For two material combinations used in this investigation, the coefficient of friction shows insignificant sensitivity to applied load values and large sensitivity to material combinations. For specific wear rate, PA6 + 20% mica composite has shown insensitivity to change in load, speed and materials combination while PSU + 20% glass fibre composite has shown high sensitivity to the change in load and material combinations. The friction coefficient of PA6 + 20% mica and PSU + 20 glass fibre rubbing against the AISI 4140 steel disc is between 0·35 and 0·40. In rubbing against PPS + 30% glass fibre their values were between 0·25 and 0·30. Specific wear rate for PA6 + 20% mica and PSU + 20% glass fibre composites are in the order of 10 − 13 to 10 − 14 m2/N. Finally, the wear mechanisms are a combination of adhesive and abrasive wear processes. In terms of application, especially in electrical systems, a substantial contribution was provided to extend switch life. Thus, besides robustness, this also ensured safety for the system and the users against undesirable situations.