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1.
PTFE coatings were deposited on the Si3N4/TiC ceramic substrate by using spray technology. The surface and cross-section micrographs, adhesive force of coatings with substrate, surface roughness and micro-hardness of the coated ceramics were examined. The friction and wear behaviors of ceramic samples with and without coatings were investigated through carrying out dry sliding friction tests against WC/Co ball. The test results indicated that the coated ceramics exhibited rougher surface and lower micro-hardness, and the PTFE coatings can significantly reduce the surface friction and adhesive wear of ceramics. The friction performance of PTFE-coated sample was affected by applied load due to the lower surface hardness and shear strength of coatings, and the main wear failure mechanisms were abrasion wear, coating delamination and flaking. It can be considered that deposition of PTFE coatings is a promising approach to improve the friction and wear behavior of ceramic substrate.  相似文献   

2.
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.  相似文献   

3.
In this work, a macromolecular coupling agent (BA‐MAA‐AN tercopolymer) was used for surface modification of native nano‐sized silicon nitride (Si3N4) powder. This modification strategy was designed for preparing nano‐Si3N4/NBR composites. The structure and surface properties of modified nano‐Si3N4 were systematically investigated by FTIR, XPS, TGA, TEM, Size Distributions Analyzer, and Contact Angle Measurement. It was found that, the optimum loading of BA‐MAA‐AN tercopolymer coated on the surface of nano‐sized Si3N4 is 10% of nano‐Si3N4. According to the spectra of FTIR, XPS and TGA, it can be inferred that this macromolecular coupling agent covalently bonds on the surface of nano‐sized Si3N4 particles and an organic coating layer is formed. The contact angle experiments show that the hydrophobic property of nano‐sized Si3N4 modified with macromolecular coupling agent is improved obviously. TEM reveals that modified nano‐Si3N4 possesses good dispersibility and the average diameter in NBR is less than 100 nm. It has also been found that the oil resistance of NBR based nanocomposites is improved greatly due to the modified nano‐Si3N4. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

4.
A new macromolecular coupling agent butyl acrylate (BA)‐methyl methacrylate (MMA)‐vinyl triethoxy silane (VTES) tercopolymer was synthesized using solution polymerization initiated by free radical initiator benzoyl peroxide (BPO) and dicumyl peroxide (DCP). Dodecylthiol is choosed as the chain transfer to control the molecule weight of this tercopolymer. The terpolymer's molecular structure was confirmed by FTIR and NMR, and its average molecular weight was determined by GPC. In this work, the tercopolymer BA–MMA–VTES is used for surface modification of silicon nitride (Si3N4) nanopowder. The structure surface properties and thermal stability of modified nano‐Si3N4 were systematically investigated by FTIR, TGA, TEM, and size distribution analyzer. The results show that the macromolecular coupling agent bonds covalently on the surface of nano‐sized Si3N4 particles and an organic coating layer is formed. The optimum loading of this macromolecular coupling agent BA–MMA–VTES tercopolymer is 5% (wt %) of nano‐sized Si3N4. TEM also reveals that modified nano‐Si3N4 possesses good dispersibility. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

5.
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  相似文献   

6.
Nano‐micro hierarchical porous polyphenylene sulfide/polytetrafluoroethylene (PPS/PTFE) composites were prepared by mold‐leaching and vacuum melting process under high temperature condition. The tribological behaviors of porous PPS/PTFE composites and the synergism as a result of incorporation of both micro‐porogen (NaCl) and mesoporous TiO2 whiskers were investigated. The effects of mesoporous TiO2 whiskers and nonperforated TiO2 whiskers on the friction and wear properties of PPS/PTFE composites were comparatively studied, respectively. Results indicated that the wear rate of porous PPS/PTFE composites with 30 wt % NaCl and 7 wt % mesoporous TiO2 whiskers obtained the lowest values under the load of 100 N. Compared with pure PPS, the wear resistance of nano‐micro porous PPS/PTFE composite was enhanced by 6.45 × 103 times, showing outstanding wear resistance. During sliding condition, grease could be squeezed through the nano‐micro pores under the coupling effect of load and friction heat, and formed a lubricanting layer on friction surface, providing self‐lubricating effect and high wear resistance. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

7.
The effects of various filler concentrations (0.1, 0.5, 1, 1.5, 2, 2.5, and 3 wt %) on the tribological and mechanical properties of carbon‐nanofiber (CNF)‐filled polytetrafluoroethylene (PTFE) composites were studied. Moreover, the influence of various loads (50, 100, 150, and 200 N) and sliding velocities (0.692 and 1.39 m/s) on the friction and wear behaviors of the PTFE composites was investigated. The results showed that the friction coefficients of the PTFE composites decreased initially up to a 0.5 wt % filler concentration and then increased, whereas the antiwear properties of the PTFE composites increased by 1–2 orders of magnitude in comparison with those of pure PTFE. The composite with a 2 wt % filler concentration had the best antiwear properties under all friction conditions. The friction coefficients of the CNF/PTFE composites decreased with increases in the load and sliding velocity, whereas the wear volume loss of the PTFE composites increased. At the same time, the results also indicated that the mechanical properties of the PTFE composites increased first up to a 1 wt % filler concentration and then decreased as the filler concentration was increased above 1 wt %. In comparison with pure PTFE, the impact strength, tensile strength, and elongation to break of the PTFE composites increased by 40, 20, and 70%, respectively, at a 1 wt % filler concentration. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2430–2437, 2007  相似文献   

8.
《Ceramics International》2022,48(1):514-524
To enhance the tribological properties of Si3N4 based ceramics, surface textures of dimples combined with DLC coatings are fabricated on Si3N4/TiC ceramic surface by nanosecond laser and plasma enhanced chemical vapor deposition (PECVD). The dry friction and wear performances are evaluated by unidirectional sliding friction tests using a rotary ball-on-disk tribometer. Results reveal that the friction and wear properties of Si3N4/TiC ceramics are significantly enhanced by DLC coatings or dimpled textures, and the DLC coatings combined with dimpled textures show the best efficiency in reducing friction, adhesion and wear. This improvement can be explained by the synergistic effect of DLC coatings and surface textures, and the synergistic mechanisms are attributed to the formation of lubrication film and secondary lubrication, debris capture of dimpled textures, increased surface hardness and mechanical interlocking effect, and reduced contact area.  相似文献   

9.
《Ceramics International》2019,45(16):20243-20250
Different additives (metals, ceramics, and metal/ceramic assembles) were incorporated into chromium oxide (Cr2O3) coatings to improve its wear resistance. The doping or co-doping effects were compared in terms of the microstructure, phase composition, microhardness and sliding wear properties of plasma-sprayed Cr2O3-7wt.% Mo, Cr2O3-7wt.% Nb2O5, Cr2O3-4wt.% MoO3-3wt.% Mo, and Cr2O3-4wt.% Nb2O5-3wt.% Mo coatings. Under the low sliding loads, the composite coatings mated with WC-Co counterparts have lower friction coefficients than those against Si3N4, which are inverse with their microhardnesses, but more obvious fatigue wear characteristics. Under the high sliding loads, Mo/Nb2O5 co-doped Cr2O3 coating (CNM) has the best wear resistance than other coatings, due to the delaying co-effects of crack formation and propagation on basis of the crack deflection and the toughening effects of Mo additives and the high hardness of Nb2O5 additives. As the reciprocating sliding loads exceed the critical stress of brittle Cr2O3-based coatings, the coating detachments occur, displaying obvious fatigue wear characteristics.  相似文献   

10.
Five kinds of polytetrafluoroethylene (PTFE)-based composites were prepared: PTFE, PTFE + 30 vol % SiC, PTFE + 30 vol % Si3N4, PTFE + 30 vol % BN, and PTFE + 30 vol % B2O3. The friction and wear properties of these ceramic particle filled PTFE composites sliding against GCr15 bearing steel under both dry and liquid paraffin lubricated conditions were studied by using an MHK-500 ring-block wear tester. The worn surfaces and the transfer films formed on the surface of the GCr15 bearing steel of these PTFE composites were investigated by using a scanning electron microscope (SEM)and an optical microscope, respectively. The experimental results show that the ceramic particles of SiC, Si3N4, BN, and B2O3 can greatly reduce the wear of the PTFE composites; the wear-reducing action of Si3N4 is the most effective, that of SiC is the next most effective, then the BN, and that of B2O3 is the worst. We found that B2O3 reduces the friction coefficient of the PTFE composite but SiC, Si3N4, and BN increase the friction coefficients of the PTFE composites. However, the friction and wear properties of the ceramic particle filled PTFE composites can be greatly improved by lubrication with liquid paraffin, and the friction coefficients of the PTFE composites can be decreased by 1 order of magnitude. Under lubrication of liquid paraffin the friction coefficients of these ceramic particle filled PTFE composites decrease with an increase of load, but the wear of the PTFE composites increases with a load increase. The variations of the friction coefficients with load for these ceramic particle filled PTFE composites under lubrication of liquid paraffin can be properly described by the relationship between the friction coefficient (μ) and the simplified Sommerfeld variable N/P as given here. The investigations of the frictional surfaces show that the ceramic particles SiC, Si3N4, BN, and B2O3 enhance the adhesion of the transfer films of the PTFE composites to the surface of GCr15 bearing steel, so they greatly reduce the wear of the PTFE composites. However, the transfer of the PTFE composites onto the surface of the GCr15 bearing steel can be greatly reduced by lubrication with liquid paraffin, but the transfer still takes place. Meanwhile, the interactions between the liquid paraffin and the PTFE composites, especially the absorption of liquid paraffin into the surface layers of the PTFE composites, create some cracks on the worn surfaces of the ceramic particle filled PTFE composites; the creation and development of these cracks reduces the load-supporting capacity of the PTFE composites. This leads to the deterioration of the friction and wear properties of the PTFE composites under higher loads in liquid paraffin lubrication. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2611–2619, 1999  相似文献   

11.
Si3N4‐based nanocomposites containing 0–50 wt% TiC0.37N0.63 are directly consolidated at 1700°C by spark plasma sintering, and their reciprocal sliding behavior against a Si3N4 counterbody is investigated under a maximum Hertzian stress of 1.27 GPa in unlubricated conditions. The average grain widths of Si3N4 and TiC0.37N0.63 are about 85 and 90 nm, respectively. The decreasing relative densities of the as‐sintered nanocomposites indicate that the nano‐TiC0.37N0.63 may introduce pores and reduce the hardness and fracture resistance of the materials. The brittleness index for sliding contacts in all the samples is 25–31, indicating brittle fracture taking place on the wear surface and inducing cavities. When the mean free paths of nano‐TiC0.37N0.63 are slightly greater than grain length of Si3N4, the best wear resistance is achieved in Si3N4 containing 20/30 wt% TiC0.37N0.63 due to the process of surface smoothing by triboproducts. Severe wear response can be observed in Si3N4 nanocomposites containing 0, 10, 40, and 50 wt% of TiC0.37N0.63. The wear responses are explained by considering the microstructural parameters (like grain characteristics for both phases and mean free path of nano‐TiC0.37N0.63) and contact‐induced fracturing behavior, as well as tribochemical reactions.  相似文献   

12.
This work is part of a program on composites used in thermoelectric devices. Tribological properties of dynamic vulcanizate blends of polypropylene and ethylene‐propylene‐diene rubber filled with 5 wt% of microscale powder have been studied. The microscale thermal‐shock‐resistant ceramic filler contains α‐Al2O3, mullite (3Al2O3 · 2SiO2 or 2Al2O3SiO2), β‐spodumene glass‐ceramic and aluminium titanate. We found that our ceramic particles are abrasive; they cause strong abrasion of softer steel ball surfaces during dry sliding friction. To overcome the difficulty of particle dispersion and adhesion, the filler was modified through grafting using three types of organic molecules. Dry sliding friction was measured using four types of counter‐surfaces: tungsten carbide, Si3N2, 302 steel and 440 steel. Thermoplastic vulcanizate filled with neat ceramic powder shows the lowest friction compared to composites containing the same but surface‐treated powder. We introduce a ‘bump’ model to explain the tribological responses of our composites. ‘Naked’ or untreated ceramic particles protrude from the polymer surface and cause a decrease of the contact area compared to neat polymer. The ball partner surface has only a small contact area with the bumps. As contact surface area decreases, so does friction and the amount of heat generated during sliding friction testing. Chemical coupling of the ceramic to the matrix smoothens the bumps and increases the contact surface, giving a parallel increase in friction. Copyright © 2012 Society of Chemical Industry  相似文献   

13.
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  相似文献   

14.
Polytetrafluoroethylene (PTFE) composite coatings doped with copper acetate and polyethylene (PE) were fabricated on rubber substrate by electron beam dispersion technique. The effects of dopant nature and glow discharge treatment on morphology, structural and tribological properties of the coatings were investigated. The results showed that Cu and PE doping change the surface structure of PTFE‐based composite coatings due to the chemical reactions between the dispersion products. Cu‐PE‐PTFE coatings show the columnar and layered growth models without and with discharge treatment. Cu adding decreases the crystallinity, branched degree and unsaturated degree of PE coatings, but increases the branched degree and unsaturated bonds in the PE‐PTFE coatings. Glow discharge enhances the crystallinity and ordering degree of composite coatings. Friction experiments indicated the significant difference of composite coatings in the nature of their destruction during friction. PE‐PTFE coating is characterized of the brittle fracture with clear failure boundaries but Cu‐PE‐PTFE coating shows a rough surface without cracking and delaminating after friction. Cu doping increases the dynamic coefficient of friction of PE and PE‐PTFE composite coatings, but discharge plasma decreases the dynamic coefficient of friction. Cu‐PE‐PTFE composite coating after discharge treatment has the decreased dynamic coefficient of friction and improved wear resistance. POLYM. ENG. SCI., 58:103–111, 2018. © 2017 Society of Plastics Engineers  相似文献   

15.
A nano‐composite coating was formed using nano‐ZnO as pigment in different concentrations, to a specially developed alkyd‐based waterborne coating. The nano‐ZnO modified composite coatings were applied on mild steel substrate by dipping. The dispersion of nano‐ZnO particles in coating system was investigated by scanning electron microscopic and atomic force microscopic techniques. The effect of the addition of these nano‐pigments on the electrochemical behavior of the coating was investigated in 3.5% NaCl solution, using electrochemical impedance spectroscopy. Coating modified with higher concentration of nano‐ZnO particles showed comparatively better performance as was evident from the pore resistance (Rpo) and coating capacitance (Cc) values after 30 days of exposure. In general, the study showed an improvement in the corrosion resistance of the nano‐particle modified coatings as compared with the neat coating, confirming the positive effect of nano‐particle addition in coatings. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

16.
《Ceramics International》2017,43(9):6976-6986
Although the friction and wear behavior of plasma sprayed aluminum matrix ceramic coatings have been extensively discussed in the last decades, only few researches have been carried out the wear mechanisms sliding against different pairs. The tribological behaviors of plasma sprayed Al2O3 coating sliding against ZrO2, Si3N4, Al2O3 and stainless steel balls in air were comparatively investigated in this study. It was showed that Al2O3 coating sliding against different counterparts exhibited diverse tribological behaviors, which could be mainly ascribed to the different mechanical properties of counterparts. Meanwhile, the tribochemical reactions influenced the friction performances significantly. Moreover, the transform of γ-Al2O3 to α-Al2O3 occurred during the friction, which was closely related to the coefficient of friction and thermal conductivities of counterparts. The main wear of Al2O3 coating sliding against ceramic materials resulted from the brittle fracture and abrasive wear. While it was dominated by adhesive wear when sliding against stainless steel, and accompanied with abrasive wear.  相似文献   

17.
This is a comparative study between ultrahigh molecular weight polyethylene (UHMWPE) reinforced with micro‐ and nano‐hydroxyapatite (HA) under different filler content. The micro‐ and nano‐HA/UHMWPE composites were prepared by hot‐pressing method, and then compression strength, ball indentation hardness, creep resistance, friction, and wear properties were investigated. To explore mechanisms of these properties, differential scanning calorimetry, infrared spectrum, wettability, and scanning electron microscopy with energy dispersive spectrometry analysis were carried out on the samples. The results demonstrated that UHMWPE reinforced with micro‐ and nano‐HA would improve the ball indentation hardness, compression strength, creep resistance, wettability, and wear behavior. The mechanical properties for both micro‐ and nano‐HA/UHMWPE composites were comparable with pure UHMWPE. The mechanical properties of nano‐HA/UHMWPE composites are better compared with micro‐HA/UHMWPE composites and pure UHMWPE. The optimum filler quantity of micro‐ and nano‐HA/UHMWPE composites is found to be at 15 wt % and 10 wt %, separately. The micro‐ and nano‐HA/UHMWPE composites exhibit a low friction coefficient and good wear resistance at this content. The worn surface of HA/UHMWPE composites shows the wear mechanisms changed from furrow and scratch to surface rupture and delamination when the weight percent of micro‐ and nano‐HA exceed 15 wt % and 10 wt %. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42869.  相似文献   

18.
Five kinds of polytetrafluoroethylene (PTFE)‐based composites, pure PTFE, PTFE + 30(v)% MoS2, PTFE + 30(v)% PbS, PTFE + 30(v)% CuS, and PTFE + 30(v)% graphite (GR) composites, were first prepared. Then the friction and wear properties of these PTFE composites, sliding against GCr15‐bearing steel under both dry and liquid paraffin‐lubricated conditions, were studied by using an MHK‐500 ring‐on‐block wear tester. Finally, the worn surfaces and the transfer films of the PTFE composites formed on the surface of GCr15 bearing steel were investigated by using a scanning electron microscope (SEM) and an optical microscope, respectively. Experimental results show that filling with MoS2, PbS, CuS, or graphite to PTFE can reduce the wear of the PTFE composites by two orders of magnitude compared to that of pure PTFE under dry friction conditions. However, the friction and wear‐reducing properties of these PTFE composites can be greatly improved by lubrication with liquid paraffin. Investigations of transfer films show that MoS2, PbS, CuS, and graphite promote the transfer of the PTFE composites onto the surface of GCr15‐bearing steel under dry friction conditions, but the transfer of the PTFE composites onto the surface of GCr15‐bearing steel can be greatly reduced by lubrication with liquid paraffin. SEM examinations of worn surfaces show that with lubrication of liquid paraffin, the creation and development of the cracks occurred on the worn surfaces of the PTFE composites under load, which reduces the load‐supporting capacity of the PTFE composites. This would lead to the deterioration of the friction and wear properties of the PTFE composites under higher loads (>600N). © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 751–761, 1999  相似文献   

19.
Silicon nitride (Si3N4) materials with preferentially aligned β‐Si3N4 grains were tribologically characterized with respect to their possible application in a high‐pressure gasoline pump. Tribological tests were performed under oscillating sliding conditions lubricated with isooctane as a substitute for gasoline using Si3N4 counterbodies. Performance in terms of wear of the aligned materials surpassed that of nonaligned reference Si3N4, as well as that of self‐mated silicon carbide, zirconia, alumina, and a steel sliding pair. The plane perpendicular to the extruding direction and parallel to the hot‐pressing axis was the most wear resistant.  相似文献   

20.
Polytetrafluoroethylene (PTFE) particles were irradiated with 60Co γ‐ray to improve their dispersing capacity in polyurethane (PU), which was used as a binder of a PTFE‐based bonded solid lubricating coating. The PU/PTFE‐bonded solid lubricating coating was prepared on a steel block by spraying and curing at room ambient, and the tribological properties of the PU/PTFE coatings were evaluated on a ring‐on‐block tester at a speed of 1.25–2.5 m/s and a load of 314–785 N. The wear life of bonded coatings on PTFE volume concentrations, curing humidities and times, coating thickness, and sliding conditions was also investigated. It was found that a 60‐μm thickness coating, which has a 40% PTFE volume concentration, cured at 75% relative humidity for 4 days, has a longer wear life of 844 m/μm at 314 N and 1.25 m/s. The PTFE/PU coating was wear‐resistant when the load × speed value was less than 687 Nm/s?1; at same time, the wear life for a thinner coating is sensitive to sliding condition variations. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3454–3459, 2002  相似文献   

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