Polycarbonate/molybdenum disulfide/carbon black composites: Physicomechanical,thermal, wear,and morphological properties

To investigate the influence of molybdenum disulfide (MoS₂) as solid lubricant and filler on the polycarbonate (PC) and carbon black (CB) composites, PC containing one weight percentage of CB powder was compounded and extruded with 0.5, 1.0, 2.0, and 3.0 weight percentage of MoS₂ powder in a co‐rotating twin screw extruder. Thus, the fabricated PC/CB/MoS₂ composites were characterized for physicomechanical properties such as density, void content, surface hardness, tensile behaviors, and impact strength. The thermal characteristics of the composites have been studied by differential scanning calorimetry and dynamic mechanical analysis (DMA). The effect of MoS₂ content, loads and sliding distances on wear characteristics of the composites were evaluated using pin‐on‐disc equipment. It was found that wear, friction, and laser etching resistance of PC/CB/MoS₂ composites increased with increase in MoS₂ content along with improvement in tensile and impact strengths. DMA analysis indicates the storage modulus of PC/CB/MoS₂ composites increased with increase in MoS₂ content below the glass transition temperature (T_g) of PC. Worn surfaces and laser etched surfaces were examined with scanning electron microscopy and optical microcopy respectively to have better insight of the wear and laser etching mechanism. It was observed that the MoS₂ as solid lubricant played major role in improving resistance to wear, friction, and laser etching. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Study on the Friction and Wear Behaviors of Modified PA66 Composites

The wear-resistant polyamide 66 (PA66) composites were prepared and the mechanical properties, friction and wear properties were inspected. Results show that GF, PTFE and MoS₂ can improve the mechanical, friction and wear properties of PA66 composites. PTFE is more effective on the friction and wear properties than MoS₂ when GF is 30%wt. The best effect of the modification is 35%wt GF when both PTFE and MoS₂ were added. Friction coefficient first increase, then reduce to be stable as sliding time increases. Friction coefficient and wear mass loss increase as load increases. The main wear mechanisms are fatigue and abrasion wears.     

Mechanical and tribological properties of polyoxymethylene modified with nanoparticles and solid lubricants

Polyoxymethylene (POM) composites modified with nanoparticles, polytetrafluoroethylene (PTFE) and MoS₂ were prepared by a twin‐screw extruder. The effect of nanoparticles and solid lubricant PTFE/MoS₂ on mechanical and tribological properties of the composites were studied. Tribological tests were conducted on an Amsler friction and wear tester using a block‐on‐ring arrangement under dry sliding and oil lubricated conditions, respectively. The results showed that generally speaking POM nanocomposites had better stiffness and tribological properties than corresponding POM composites attributed to the high surface energy of nanoparticles, except that the tensile strength of three composites and dry‐sliding tribological properties of POM/3%Al₂O₃ nanocomposite decreased due to the agglomeration of nanoparticles. Tribological properties differed under dry sliding and oil lubricated conditions. The friction coefficient and wear volume of POM nanocomposites under oil lubricated condition decreased significantly. The increased deformation resistance supported the increased wear resistance of POM nanocomposites. POM/PTFE/MoS₂/3%Al₂O₃ nanocomposite had the best mechanical and tribological properties of all three composites, which was attributed to the synergistic effect of nanoparticles and PTFE/MoS₂. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Friction and wear behavior of basalt‐fabric‐reinforced/solid‐lubricant‐filled phenolic composites

To improve the tribological properties of basalt‐fabric‐reinforced phenolic composites, solid lubricants of MoS₂ and graphite were incorporated, and the tribological properties of the resulting basalt‐fabric composites were investigated on a model ring‐on‐block test rig under dry sliding conditions. The effects of the filler content, load, and sliding time on the tribological behavior of the basalt‐fabric composites were systematically examined. The morphologies of the worn surfaces and transfer films formed on the counterpart steel rings were analyzed by means of scanning electron microscopy. The experimental results reveal that the incorporation of MoS₂ significantly decreased the friction coefficient, whereas the inclusion of graphite improved the wear resistance remarkably. The results also indicate that the filled basalt‐fabric composites seemed to be more suitable for friction materials serving under higher loads. The transfer films formed on the counterpart surfaces during the friction process made contributions to the reduction of the friction coefficient and wear rate of the basalt‐fabric composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A study on mechanical,thermal, and wear characteristics of nylon 66/molybdenum disulfide composites reinforced with glass fibers

The influence of silane‐coated short glass fibers (SGF) on the mechanical and wear characteristics of nylon 66 composites was investigated by compounding nylon 66 with 35% SGF as well as with 2% molybdenum disulfide (MoS₂) and without MoS₂ in a co‐rotating twin screw extruder. Thus the resultant material was evaluated for physico‐mechanical, thermal, sliding wear, and morphological characteristics. It was found that the addition of glass fibers as well as MoS₂ has significantly improved the tensile strength, tensile modulus, and impact strength of the nylon 66. Differential scanning calorimetry analysis reveals significant changes in the crystallization behavior of nylon 66 for incorporation of fillers. Thermal stability of the nylon 66 was found to be improved as revealed by the thermogravimetric analysis results. Dynamic mechanical analysis results show drastic improvement in the storage modulus of the nylon 66 both in the glassy region as well as in the rubbery region. Wear analysis shows that the incorporation of glass fibers and MoS₂ filler has reduced the wear loss and specific wear rate of nylon 66. Worn surfaces were examined with scanning electron microscopy to have better insight of the wear mechanism. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Friction and wear properties of basalt fiber reinforced/solid lubricants filled polyimide composites under different sliding conditions

Short basalt fibers (BFs)‐reinforced polyimide (PI) composites filled with MoS₂ and graphite were fabricated by means of hot‐press molding technique. The tribological properties of the resulting composites sliding against GCr15 steel ring were investigated on a model ring‐on‐block test rig. The wear mechanisms were also comparatively discussed, based on scanning electron microscopic examination of the worn surface of the PI composites and the transfer film formed on the counterpart. Experimental results revealed that MoS₂ and graphite as fillers significantly improved the wear resistance of the BFs‐reinforced polyimide (BFs/PI) composites. For the best combination of friction coefficient and wear rate, the optimal volume content of MoS₂ and graphite in the composites appears to be 40 and 35%, respectively. It was also found that the tribological properties of the filled BFs/PI composites were closely related with the sliding conditions such as sliding speed and applied load. Research results show that the BF/PI composites exhibited better tribological properties under higher PV product. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

The Friction and Wear of Aramid Fiber-Reinforced Polyamide 6 Composites Filled with Nano-MoS2

The friction and wear behaviors of aramid-filled PA 6 composites filled with and without nano-MoS₂ were investigated on an end-face tribometer through rubbing against ASTM 1045 steel under dry friction. The experimental results indicated that the wear rate and the friction coefficient of PA 6 decreased with the addition of nano-MoS₂. The friction coefficients of PA 6 composites filled with aramid fiber are lower than those without nano-MoS₂. The main wear mechanisms under dry sliding condition are the plastic deformation and mechanical microploughing. For best combination of friction coefficient and wear rate, the optimal volume content of MoS₂ in the composites appears to be 10 vol %.     

Sliding Wear Performance of TiO2/Short Carbon Fiber/Polyamide 66 Hybrid Composites

In the present work, polyamide 66 (PA66) based composites filled with hybrid TiO₂ particles and short pitch based carbon fiber were prepared. By evaluating sliding wear properties of the composites as a function of the components concentrations. Both wear rate and friction coefficient of the hybrid composites were significantly lower than those of the pure polyamide 66. The composite with 4 wt.% TiO₂ and 6 wt.% carbon fiber offered the greatest improvement of the tribological performance.     

Effect of MoS2/PTFE coatings on performance of Si3N4/TiC ceramics in dry sliding against WC/Co

To enhance the tribological performance of Si₃N₄/TiC ceramics, MoS₂/PTFE composite coatings were deposited on the ceramic substrate through spraying method. The micrographs and basic properties of the MoS₂/PTFE coated samples were investigated. Dry sliding friction experiments against WC/Co ball were performed with the coated ceramics and traditional ones. These results showed that the composite coatings could significantly reduce the friction coefficient of ceramics, and protect the substrate from adhesion wear. The primary tribological mechanisms of the coated ceramics were abrasive wear, coating spalling and delamination, and the tribological property was transited from slight wear to serious wear with the increase of load because of the lower surface hardness and shear strength. The possible mechanisms for the effects of MoS₂/PTFE composite coatings on the friction performance of ceramics were discussed.     

Effects of lubricating‐oil additives on the friction and wear properties of polymers and their composites sliding against steel under oil‐lubricated conditions

The effects of lubricating‐oil additive zinc dialkyldithiophosphate (ZDDP) on the friction and wear properties of polymers and their composites sliding against GCr15 bearing steel were studied by using an MHK‐500 ring‐on‐block wear tester (Timken wear tester). Then the frictional surfaces of the friction pairs were examined by using electron probe microanalysis (EPMA). Experimental results show that the ZDDP contained in liquid paraffin has little effect on the friction coefficients of the polyimide (PI) or polyamide 66 (PA66) against GCr15 bearing steel friction pairs compared with that under the lubrication of liquid paraffin, but it slightly reduces the friction coefficients of polytetrafluoroethylene (PTFE) or its composites against GCr15 bearing steel friction pairs. Under lubrication of liquid paraffin containing 2 wt % ZDDP, the ZDDP film absorbed on the frictional surfaces of the PTFE composites–GCr15 bearing steel friction pairs exhibits obvious antiwear properties; it greatly reduces the wear of pure PTFE and the PTFE composites filled with Pb, PbO, and MoS₂; and the wear of the PTFE composites can be reduced by one order of magnitude compared with that under lubrication of pure liquid paraffin. Meanwhile, the inorganic fillers Pb, PbO, and MoS₂ contained in PTFE have little effect on the absorption of ZDDP to the frictional surfaces, so they have little effect on the friction coefficients of the PTFE composites–GCr15 bearing steel friction pairs under the lubrication of liquid paraffin containing 2 wt % ZDDP. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1240–1247, 2000     

Mechanical and tribological behaviors of PA66/PVDF blends filled with calcium sulphate whiskers

The mechanical and tribological performance of the PA66/PVDF blends filled with various amount of calcium sulphate whiskers (CSW) was investigated. The whiskers improve the tensile and flexural performance of the PA66/PVDF blends. Meanwhile, the addition of CSW obviously decreases friction coefficient and improves the wear resistance of the blends. With the further increase of CSW, friction coefficient of the blends relatively keeps stable and the wear resistance of the blends slightly decreases. The PA66/PVDF blends filled with 5 wt% CSW exhibited the best anti‐wear ability. FTIR analysis shows that the chemical change has not occurred in the debris. XPS analysis shows that some tribo‐chemical reactions have occurred during friction process and produces some compounds such as FeF₂, Fe₂O₃ on the transfer film surfaces. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers     

Tribological behavior of the polyamide composite coating filled with different fillers under dry sliding

The polyamide (PA) composite coating filled with the particles of microsized MoS₂, microsized graphite, and nano‐Al₂O₃, respectively, were prepared by flame spraying. The friction and wear characteristics of the PA coating and composite coating filled with the varied content of filler under dry sliding against stainless steel were comparatively investigated using a block‐ring tester. The morphologies of the worn surfaces and transfer films on the counterpart steel ring were observed on a scanning electron microscope. The result showed that the addition of fillers to the composite coatings changed significantly the friction coefficient and wear rate of the coatings. The composite coatings filled with a low level content of fillers showed lower wear rate than did pure PA coating under dry sliding; especially the MoS₂/PA composite coating had the lowest wear rate among these composite coatings. The composite coatings with a high level content of fillers had higher wear rate than did pure PA coating, except of the Al₂O₃/PA composite coating. The bonding strengths between the polymer matrix and fillers changed with the content of the fillers, which accounted for the differences in the tribological properties of the composite coatings filled with the varied content fillers. On the other hand, the difference in the friction and wear behaviors of the composite coatings and pure coating were attributed to the difference in their worn surface morphologies and transfer film characteristics. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Graphite fluoride and fluorographene as a new class of solid lubricant additives for high‐performance polyamide 66 composites with excellent mechanical and tribological properties

Fluorographene (FG) with layer numbers of 3–4 was successfully prepared through facile microwave‐assisted liquid phase exfoliation of raw graphite fluoride (GrF). The raw GrF and the as‐prepared FG were then directly incorporated into polyamide 66 (PA66) by melt processing without using any surfactants. Microstructural, mechanical and tribological properties of the prepared PA66 composites were investigated. Various characterization results showed that both GrF and FG, as novel solid lubricants, can effectively improve the mechanical and anti‐wear performances of the PA66 matrix. It was also found that FG is better at improving mechanical properties and reducing the friction of PA66 than GrF at low concentrations owing to the large surface–volume ratio. The addition of 0.5 wt% FG into PA66 exhibits a ca 13% increase in tensile modulus, ca 5% increase in tensile strength, ca 18% reduction in coefficient of friction (COF) and ca 43% reduction in wear rate. However, at relatively high concentrations, such as 1.0 wt%, GrF shows a better reinforcement effect than FG owing to a uniform dispersion of GrF in the PA66 matrix. The addition of 1.0 wt% GrF into PA66 exhibits a ca 18% increase in tensile modulus, ca 5% increase in tensile strength, ca 37% reduction in COF and ca 46% reduction in wear rate. Wear tests also show that the excellent wear resistance of the PA66 composites is due to the improved mechanical properties and the lubrication of GrF and FG between the worn surfaces. Our current work demonstrates the tremendous potentials of fluorinated carbon materials for enhancing mechanical and anti‐wear properties of polymeric materials. © 2020 Society of Chemical Industry     

Processing and tribology of thermoplastic polyurethane particulate composite materials

The processing, mechanical and tribological properties of wax containing thermoplastic polyurethane–filler composites were studied for different weight ratios of graphite, TiO₂, MoS₂, and ZrO₂ microparticles and SiO₂ nanoparticles. The composites were compounded by extrusion and processed by compression molding. The rheological, thermal, and mechanical properties were measured, and the wear characteristics were tested with ball-on-plate reciprocating tribometer tests under fixed friction conditions and then observed by scanning electron microscopy. Correlations between the friction, wear, and mechanical properties were observed, and their mechanisms are discussed. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

The Effect of Arylboronic Acid Treatment of Carbon Fiber on the Mechanical and Tribological Properties of PA66 Composites

PA66 composites filled with surface-treated carbon fiber were prepared by twin-screw extruder in order to study the influence of carbon fiber surface arylboronic acid treatment on the mechanical and tribological behavior of the PA66 composites (CF/PA66). The mechanical property, friction and wear tests of the composites with untreated and treated carbon fiber were performed and the worn surface morphology was analyzed. The results show that the worn surface area of the treated carbon fiber was far smoother than that of the untreated carbon fiber and there formed a bonding adhesion on the carbon fiber surface after treatment. The tensile strength of CF/PA66 composites with surface arylboronic acid treatment was improved. The friction coefficient and wear of arylboronic acid treated CF/PA66 composites were apparently lower than that with untreated carbon fiber. In conclusion, the surface treatment favored the improvement of the higher interface strength and so had good effect on improving the tribological properties of the composites.     

Effect of several solid lubricants on the mechanical and tribological properties of phenolic resin‐based composites

The flake graphite, polytetrafluoroethylene, and molybdenum disulfide (MoS₂) filled phenolic resin‐based composites were prepared by hot press molding. The thermal, mechanical, and tribological properties of composites were studied systematically. The morphologies of the worn surfaces and the change of chemical compositions during the sliding process of the composites were analyzed by scanning electron microscopy and X‐ray photoelectron spectroscopy, respectively. It was found that the heat‐resisting performance and the hardness of the composites are less affected by solid lubricants, while the solid lubricants did harm to the flexural strength of the composites. The friction and wear behaviors of composites highly depended on the volume fractions of solid lubricants and the sliding conditions. The wear resistance increases and the coefficient of friction decreases when the filler load increases. In addition, the appropriate content of solid lubricants is beneficial to reducing the sensitivities of the composites to load and sliding speed. POLYM. COMPOS., 36:2203–2211, 2015. © 2014 Society of Plastics Engineers     

Structural,thermal, and tribological properties of intercalated polyoxymethylene/molybdenum disulfide nanocomposites

Intercalated polyoxymethylene (POM)/molybdenum disulfide (MoS₂) nanocomposites were prepared by in situ intercalation/polymerization. The structures of the composites were characterized by means of powder X‐ray diffraction (XRD) and transmission electron microscopy. The XRD pattern showed that the polymer was inserted into the MoS₂ galleries. The interlayer spacing of the intercalated phase increased from 6.15 to 11.18 Å. The thermal behavior of the composites was also investigated through thermogravimetric analysis. The results show that the heat resistance of the intercalated composites decreased slightly. The tribological behavior of POM/MoS₂ was investigated on an MQ‐800 end‐face tirbometer under dry friction. The worn surfaces were observed by scanning electron microscopy. The results show that POM/MoS₂ presented better friction reduction and wear resistance, especially under high load. The friction mechanism of the nanocomposites is also discussed in association with X‐ray photoelectron spectroscopy. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Friction behavior of TiN–MoS2/PTFE composite coatings in dry sliding against SiC

To improve the dry friction behavior of traditional hard coatings, MoS₂/PTFE lubricating coatings were prepared on the PVD TiN-coated cemented carbide using spray method. The influences of MoS₂/PTFE lubricating coatings on the primary characteristics of TiN coatings were investigated. Reciprocating sliding tests were carried out with the TiN–MoS₂/PTFE coated specimen (T-M-P) under dry sliding conditions, and the tribological behaviors were compared to those of the TiN-coated one (T-N). The test results indicated that the adhesion force of coatings with substrate for T-M-P specimen increased, the surface micro-hardness, roughness and friction coefficient significantly decreased. Meanwhile, the surface adhesions and abrasion grooves of T-M-P specimen were reduced, and the main wear forms of T-M-P were abrasion wear and coating delamination. The MoS₂/PTFE lubricating coatings can be considered effective to improve the friction properties of traditional hard coatings.     

Effect of transfer film on tribological behavior of polyamide 66‐based binary and ternary nanocomposites

BACKGROUND: In a polymer–metal sliding system, the formation and performance of the transfer film have important effects on the tribological behavior of the polymer. In order to reveal the wear mechanism of polyamide 66 (PA 66) and its composites consisting of styrene–(ethylene/butylene)–styrene triblock rubber grafted with maleic anhydride (SEBS‐g‐MA) particles and organoclay nano‐layers, the tribological behavior and transfer films of polyamide 66 and its composites were investigated under dry sliding. RESULTS: The incorporation of SEBS‐g‐MA rubber particles reduces the wear mass loss of PA 66, while the addition of organoclay nano‐layers increases the wear mass loss. The transfer films formed by neat PA 66 and PA 66/organoclay binary nanocomposite include a dark portion and bright portion. In the dark portion, the transfer film is thicker; in the bright portion, the steel ring surface is exposed. The transfer film formed by PA 66/SEBS‐g‐MA/organoclay ternary nanocomposite is thinner and more uniform than the transfer films formed by the other materials. CONCLUSION: When SEBS‐g‐MA rubber particles and organoclay nano‐layers are added simultaneously to PA 66, the wear resistance of PA 66 can be improved markedly. The main reason is that PA 66/SEBS‐g‐MA/organoclay ternary nanocomposite can form a thin and uniform transfer film on the steel ring surface. Copyright © 2008 Society of Chemical Industry     

Investigation on thermal stability and tribological properties of ZrB2 particles filling cyanate ester resin composites by experiments and numerical simulation

The thermal stability and tribological properties of cyanate ester (CE) composites filled with Zirconium boride (ZrB₂) particles were investigated by experimental and numerical simulation. The results of thermogravimetric analysis and differential scanning calorimetry showed that the thermal stability of composites was improved by introduction of ZrB₂ particles. The tribological properties of composites including friction coefficient and wear rate measured by pin‐on‐disk friction and wear tester were enhanced. Friction coefficient and wear rate of composites were decreased significantly with an increase of ZrB₂ particles content under dry and oil sliding conditions. The 5 wt% ZrB₂ particles reinforced CE resin composite presented optimal thermal stability and tribological performance due to good dispersion of ZrB₂ particles. The worn surfaces of composites were observed by scanning electron microscopy to explore wear mechanism, indicating that the dominant wear mechanism of composites was transformed from adhesive wear to abrasive wear after incorporation of ZrB₂ particles. Finite element model was established to study the distribution of friction stress. The results revealed that filling ZrB₂ particles in the friction process of composites could bear more friction stress than CE resin matrix, which further illustrated that abrasive wear is main wear mechanism of ZrB₂/CE resin composites. POLYM. ENG. SCI., 59:602–607, 2019. © 2018 Society of Plastics Engineers