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1.
The self-lubricating composites Ni3Al–BaF2–CaF2–Ag–Cr, which have varying fluoride contents, were fabricated by the powder metallurgy technique. The effect of fluoride content
on the mechanical and tribological properties of the composites was investigated. The results showed that an optimal fluoride
content and a balance between lubricity and mechanical strength were obtained. The Ni3Al–6.2BaF2–3.8CaF2–12.5Ag–10Cr composite showed the best friction coefficients (0.29–0.38) and wear rates (4.2 × 10−5–2.19 × 10−4 mm3 N−1 m−1) at a wide temperature range (room temperature to 800°C). Fluorides exhibited a good reduced friction performance at 400
and 600°C. However, at 800°C, the formation of BaCrO4 on the worn surface due to the tribo-chemical reaction at high temperatures provided an excellent lubricating property. 相似文献
2.
A high-temperature self-lubricating composite NiAl–Cr–Mo–CaF2 was fabricated using the powder metallurgy technique, and the tribological behavior of the composite at a wide range of temperatures
(room temperature to 1000 °C) was investigated. The results showed that the composite had a favorable friction coefficient
of about 0.2 and an excellent wear resistance of about 1 × 10−5 mm3N−1m−1 at the high temperatures tested (800 and 1000 °C). The excellent self-lubricating performance was attributed to the formation
of the glaze film on the worn surface consisting mainly of CaCrO4 and CaMoO4 as high-temperature solid lubricants. 相似文献
3.
Ni3Al–Ag–BaF2/CaF2–W composites were fabricated by the powder metallurgy route, and their tribological properties over a wide temperature range,
starting from room temperature up to 800 °C, were investigated. The Ni3Al matrix composite with 15 wt% BaF2/CaF2 exhibited a favorable friction coefficient (range 0.3–0.4) and wear rate (0.2–6.2 × 10−4mm3 N−1 m−1). The formation of BaWO4 and CaWO4 with lubricity on the worn surface due to a tribo-chemical reaction at high temperatures provided excellent lubricating properties.
The low friction coefficient over a broad temperature range could be attributed to the synergistic effect of Ag, BaF2/CaF2, BaWO4, and CaWO4. 相似文献
4.
The friction and wear properties of phosphor bronze and nanocrystalline nickel coatings were evaluated using a reciprocating
ball-on-plates UMT-2MT sliding tester lubricated with ionic liquid and poly-alpha-olefin containing molybdenum dialkyl dithiocarbamate,
respectively. The morphologies of the worn surfaces for the phosphor bronze and nanocrystalline nickel coatings were observed
using a scanning electron microscope. The chemical states of several typical elements on the worn surfaces were examined by
means of X-ray photoelectron spectroscopy. Results show that the phosphor bronze and nanocrystalline nickel coatings exhibited
quite different tribological behaviors under different lubricants. Phosphor bronze plate shows higher friction coefficient
(0.14) and wear rate (3.2 × 10−5 mm3/Nm) than nanocrystalline nickel coatings (average friction coefficient is 0.097, wear rate is 1.75 × 10−6 mm3/Nm) under poly-alpha-olefin containing molybdenum dialkyl dithiocarbamate lubricated conditions. The excellent tribological
performance of nanocrystalline nickel coatings under above lubricant can be attributed to the formation of MoS2 and MoO3 on the sliding surface. a quite a number of C, O and F products on worn surface of phosphor bronze than NC nickel coatings
can improve anti-wear properties while using ionic liquid as lubricant. 相似文献
5.
Nanocomposite Microstructure and Environment Self-Adapted Tribological Properties of Highly Hard Graphite-Like Film 总被引:1,自引:0,他引:1
Yongxin Wang Liping Wang S. C. Wang Guangan Zhang Robert J. K. Wood Qunji Xue 《Tribology Letters》2010,40(3):301-310
Graphite-like carbon (GLC) nanocomposite films were fabricated by DC magnetron sputtering using high pure graphite target
at ambient temperature. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) investigation showed that the as-deposited
GLC films have high concentration of sp2-hybridized carbon. High-resolution transmission electron microscopy (HRTEM) images and selected area diffraction patterns
(SADP) indicated a complex nanocomposite microstructure of the GLC films. As well as nanocrystalline graphite, a face-center
cubic (fcc) diamond with a grain size in the range of 3–8 nm were dispersed in the amorphous carbon matrix inhomogenously
and integrally. The nanocomposite GLC film had high hardness of 23 GPa, which was attributed to the mutual strengthening effect
of nanoparticles and amorphous matrix. More importantly, the as-deposited nanocomposite GLC film exhibited excellent self-adapted
tribological properties in different environments of ambient air, different relative humidity and water. The friction coefficients
were 0.053 in ambient air and 0.046 in distilled water, while specific wear rates were 4.5 × 10−16 m3 N−1 m−1 and 1.6 × 10−16 m3 N−1 m−1, respectively. The friction regimes and mechanisms in different environments were elaborated. This film is foreseen to high
potential in protecting and solid lubricating material in humidity or water environment. 相似文献
6.
Xinghua Zhang Jun Yang Jiqiang Ma Junying Hao Qinling Bi Yongmin Liang Weimin Liu 《Tribology Letters》2012,45(1):109-116
The tribological behaviour of Fe–28Al–5Cr and its composites containing 15, 25 and 50 wt% TiC (corresponding to 19.3, 31.2
and 57.6 vol%), produced by hot-pressing process, was investigated under liquid paraffine lubrication against an AISI 52100
steel ball in ambient environment at varied applied loads and sliding speeds. It was found that the wear resistance increased
and friction coefficient decreased with increasing of TiC content. The coefficients of friction are in the range of 0.09–0.14
at the given testing conditions. The wear rates of all the materials except the 50% composite are on the order of 10−6–10−5 mm3 m−1, the wear rate for the 50% composite is too low to quantify under the two sliding conditions, (50 N, 0.04 m/s) and (100 N,
0.02 m/s). The wear rates of all the materials increase as applied load increases and the increasing extent diminishes with
the increase of TiC content, but first increase slightly and then nearly remains steadiness with increasing sliding speed.
The 50 wt% composite has wear resistance about 7–20 times better than pure Fe–28Al–5Cr at different sliding parameters. The
enhanced wear resistance by TiC addition is attributed to the high hardness of the composites, as well as support of the oil
lubrication film/layer by the hard TiC phase. The worn surfaces of all the materials are analyzed by a scanning electron microscope.
The dominant wear mechanism of the Fe–28Al–5Cr and 15% composite is grooving and flaking-off, but those of the 25 and 50%
composites are mainly shallow grooving. 相似文献
7.
Studies to explore the nature of friction, and in particular thermally activated friction in macroscopic tribology, have lead
to a series of experiments on thin coatings of molybdenum disulfide. Coatings of predominately molybdenum disulfide were selected
for these experiments; five different coatings were used: MoS2/Ni, MoS2/Ti, MoS2/Sb2O3, MoS2/C/Sb2O3, and MoS2/Au/Sb2O3. The temperatures were varied over a range from −80 °C to 180 °C. The friction coefficients tended to increase with decreasing
temperature. Activation energies were estimated to be between 2 and 10 kJ/mol from data fitting with an Arrhenius function.
Subsequent room temperature wear rate measurements of these films under dry nitrogen conditions at ambient temperature demonstrated
that the steady-state wear behavior of these coatings varied dramatically over a range of K = 7 × 10−6 to 2 × 10−8 mm3/(Nm). It was further shown that an inverse relationship between wear rate and the sensitivity of friction coefficient with
temperature exists. The highest wear-rate coatings showed nearly athermal friction behavior, while the most wear resistant
coatings showed thermally activated behavior. Finally, it is hypothesized that thermally activated behavior in macroscopic
tribology is reserved for systems with stable interfaces and ultra-low wear, and athermal behavior is characteristic to systems
experiencing gross wear. 相似文献
8.
Fe3Si, Fe3Si alloys containing Cu were fabricated by arc melting followed by hot-pressing. The friction and wear behaviors of Fe3Si based alloys with and without Cu addition against Si3N4 ball in water-lubrication were investigated. The friction coefficient and the wear rates of Fe3Si based alloys decreased as the load increased. The wear rate of Fe3Si was higher than that of AISI 304. The addition of Cu can significantly improve the friction and wear properties of Fe3Si based alloys and substantially reduce the wear rates of Si3N4 ball. The wear rate of Fe3Si–10%Cu was 2.56 × 10−6 mm3 N−1 m−1 at load of 20 N and decreased to 1.64 × 10−6 mm3 N−1 m−1 at load of 90 N. The wear rate of Si3N4 ball against Fe3Si–10%Cu was 1.41 × 10−6 mm3 N−1 m−1, while the wear rate of Si3N4 ball against AISI 304 was 5.20 × 10−6 mm3 N−1 m−1 at load of 90 N. The wear mechanism was dominated by micro-ploughing. The combination of mechanical action (i.e., shear,
smear and transference of Cu) and tribochemical reaction of Si3N4 with water was responsible for the improved tribological behavior of Fe3Si alloys containing Cu under high loads. 相似文献
9.
Tuvshin Dugarjav Takeshi Yamaguchi Kei Shibata Kazuo Hokkirigawa 《Journal of Mechanical Science and Technology》2010,24(1):85-88
The friction and wear behaviors of rice husk (RH) ceramics, prepared by carbonizing the mixture of rice husk and phenol resin
at 900 °C in N2 gas environment, sliding against high carbon chromium steel (JIS SUJ2), austenitic stainless steel (JIS SUS304), and Al2O3 under dry condition were investigated using a ball-on-disk tribometer. The test results show that the friction coefficient
of RH ceramics takes very low values 0.05–0.08 and 0.06–0.11 sliding against SUJ2 and SUS304, respectively, and much higher
values around 0.14–0.23 against Al2O3. It was also shown that SUJ2 provides the lowest specific wear rate values below 10−9 mm2/N, while, those of SUS304 and Al2O3 mostly stayed between 10−9 to 10−8 mm2/N range. The worn surfaces of counterparts were observed with optical microscopy and analyzed using cross-sectional transmission
electron microscopy with energy dispersive X-ray spectroscopy and electron diffraction. It was suggested that the tribological
behaviors of RH ceramics are closely related with the formation of a transferred film, consisted of amorphous silica and carbon
particles, on a counterpart surface. The transferred film was formed readily on SUJ2 balls, whereas for SUS304 the presence
of the film was subject of the sliding conditions. Moreover, formation of the transferred film could not be detected on Al2O3 counterparts. 相似文献
10.
Self-lubricating ZrO2(Y2O3)–Al2O3–Ba
x
Sr1−x
SO4 (x = 0.25, 0.5, 0.75) composites have been fabricated by spark plasma sintering (SPS) method. The tribological properties have
been evaluated using a high-temperature friction and wear tester at room temperature and 760 °C in dry sliding against alumina
ball. The composites exhibit distinct improvements in effectively reducing friction and wear, as compared to the unmodified
ZrO2(Y2O3)–Al2O3 ceramics. The ZrO2(Y2O3)–Al2O3–Ba
x
Sr1−x
SO4 (x = 0.25, 0.5, 0.75) composites have great low and stable friction coefficients of less than 0.15 and wear rates in the order
of 10− 6mm3/Nm at 760 °C. Delamination is considered as the dominating wear mechanism of the composites at room temperature. At elevated
temperature, the formation and effective spreading of Ba
x
Sr1−x
SO4 (x = 0.25, 0.5, 0.75) lubricating films during sliding play an important role in the reduction of the friction and wear. 相似文献
11.
Ahmad A. Sorour Holger W. Strauss Richard R. Chromik Mathieu Brochu 《Tribology Letters》2011,44(2):269-278
The spark plasma sintering (SPS) process was used to fabricate a bulk Fe–Cr–B alloy (known as Armacor M) from gas-atomized
powders. The purpose of this work is to study the microstructure, hardness and tribology of this sintered bulk alloy. Post
microstructure and mechanical characterizations were performed to investigate the effects of wear on the microstructure and
mechanical properties. Microstructural analysis using X-ray diffraction (XRD), scanning electron microscope (SEM) and energy
dispersive spectroscopy (EDS) showed that SPS successfully produced a fully dense bulk material containing 67 vol.% Cr1.65Fe0.35B0.96 particles dispersed in 33 vol.% solid solution matrix consisting of Fe, Cr and Si. Using nanoindentation, the hardness of
the Cr1.65Fe0.35B0.96 particles and the matrix was found to be 24 and 6 GPa, respectively. From microindentation, the bulk hardness of the sintered
alloy was 9.7 GPa (991 HV). Dry sliding wear testing under mild conditions (i.e., initial Hertzian mean contact pressure of
280 MPa) was conducted against a stainless steel pin. The steady state coefficient of friction against Armacor M was about
0.82. The wear of Armacor M proceeded primarily by adhesive and mild oxidative wear. The wear volume for Armacor M was 80%
less than that of carbon steel and its wear rate was 5.53 × 10−6 mm3 N−1 m−1. 相似文献
12.
The rate of material removal during fixed abrasive lapping is a function of friction coefficient, the surface tension of the
lubricant and of the substrate, and the contact angles between the interfaces. In this study, the authors measured the surface
energies of materials typically found in thin film magnetic recording heads using contact angle measurements and the Lifshitz–van
der Waals acid/base approach. The different materials tested were NixFey, Al2O3, and Al2O3-TiC. Sample preparation procedures were also considered. The chemical used to wash the surface was observed to affect the
measured substrate surface energies. Surface energy values for samples washed with either acetone or hexane showed comparable
results. The NixFey gave the highest measured surface energy (46.3–48.8 mJ m−2) followed by Al2O3 (44.1–45.3 mJ m−2) and Al2O3-TiC (43.3–45.3 mJ m−2). In contrast, the oil-washed samples measured generally lower surface energy values. The study characterized the interaction
of two lubricant types against the three materials. The oil-based lubricant spreads completely on oil-washed samples mainly
because of the low surface tension of the oil (22.0 mJ m−2) and did not show measurable contact angles. In comparison, the water-soluble lubricant ethylene glycol, due to its higher
surface tension (48.0 mJ m−2), formed higher contact angles ranging from 47.2 to 59.6° on the different substrates. 相似文献
13.
Transition metal nitrides like CrN and TiN are widely used in automotive applications due to their high hardness and wear
resistance. Recently, we showed that a multilayer architecture of CrN and TiN, deposited using the hybrid—high power impulse
magnetron sputtering (HIPIMS) and direct current magnetron sputtering (DCMS)—HIPIMS/DCMS deposition technique, results in
coatings which indicate not only increased mechanical and tribological properties but also friction coefficients in the range
of diamond-like-carbon coatings when tested at RT and ambient air conditions. The modulated pulsed power (MPP) deposition
technique was used to replace the HIPIMS powered cathode within this study to allow for a higher deposition rate, which is
based on the complex MPP pulse configuration. Our results on MPP/DCMS deposited CrN/TiN multilayer coatings indicate excellent
mechanical and tribological properties, comparable to those obtained for HIPIMS/DCMS. Hardness values are around 25 GPa with
wear rates in the range of 2 × 10−16 Nm/m3 and a coefficient of friction around 0.05 when preparing a superlattice structure. The low friction values can directly be
correlated to the relative humidity in the ambient air during dry sliding testing. A minimum relative humidity of 13% is necessary
to guarantee such low friction values, as confirmed by repeated tests, which are even obtained after vacuum annealing to 700 °C.
Our results demonstrate that the co-sputtering of high metal ion sputtering techniques and conventional DC sputtering opens
a new field of applications for CrN/TiN coatings as high wear resistance and low friction coatings. 相似文献
14.
Tribological behaviors and the relevant mechanism of a highly pure polycrystalline bulk Ti3AlC2 sliding dryly against a low carbon steel disk were investigated. The tribological tests were carried out using a block-on-disk
type high-speed friction tester, at the sliding speeds of 20–60 m/s under a normal pressure of 0.8 MPa. The results showed
that the friction coefficient is as low as 0.1∼0.14 and the wear rate of Ti3AlC2 is only (2.3–2.5) × 10−6 mm3/Nm in the sliding speed range of 20–60 m/s. Such unusual friction and wear properties were confirmed to be dependant dominantly
upon the presence of a frictional oxide film consisting of amorphous Ti, Al, and Fe oxides on the friction surfaces. The oxide
film is in a fused state during the sliding friction at a fused temperature of 238–324 °C, so it takes a significant self-lubricating
effect. 相似文献
15.
Gregory J. Dudder Xueying Zhao Brandon Krick W. Gregory Sawyer Scott S. Perry 《Tribology Letters》2011,42(2):203-213
The tribology of molybdenum disulfide (MoS2)–Sb2O3–C films was tested under a variety of environmental conditions (ambient 50% RH, 10−7 Torr vacuum, 150 Torr oxygen, and 8 Torr water) and correlated with the composition of the surface composition expressed
while sliding. High friction and low friction modes of behavior were detected. The lowest coefficient of friction, 0.06, was
achieved under vacuum, while sliding in 8 Torr water and ambient conditions both yielded the highest value of 0.15. Water
vapor was determined to be the environmental species responsible for high friction performance. XPS evaluations revealed a
preferential expression of MoS2 at the surface of wear tracks produced under vacuum and an increase in Sb2O3 concentration in wear tracks produced in ambient air (50% RH). In addition, wear tracks produced by sliding in vacuum exhibited
the lowest surface roughness as compared to those produced in other environments, consistent with the picture of low friction
originating from well-ordered MoS2 layers produced through sliding in vacuum. 相似文献
16.
Tribological properties of γ-Y2Si2O7 ceramic against AISI 52100 steel and Si3N4 ceramic counterparts
Reciprocating ball-on-flat dry sliding friction and wear experiments have been conducted on single-phase γ-Y2Si2O7 ceramic flats in contact with AISI 52100 bearing steel and Si3N4 ceramic balls at 5–15 N normal loads in an ambient environment. The kinetic friction coefficients of γ-Y2Si2O7 varied in the range over 0.53–0.63 against AISI 52100 steel and between 0.51–0.56 against Si3N4 ceramic. We found that wear occurred predominantly during the running-in period and it almost ceased at the steady friction stage. The wear rates of γ-Y2Si2O7 were in the order of 10?4 mm3/(N m). Besides, wear debris strongly influenced the friction and wear processes. The strong chemical affinity between γ-Y2Si2O7 and AISI 52100 balls led to a thick transfer layer formed on both contact surfaces of the flat and counterpart ball, which changed the direct sliding between the ball and the flat into a shearing within the transfer layer. For the γ-Y2Si2O7/Si3N4 pair, a thin silica hydrate lubricant tribofilm presented above the compressed debris entrapped in the worn track and contact ball surface. This transfer layer and the tribofilm separated the sliding couple from direct contact and contributed to the low friction coefficient and wear rate. 相似文献
17.
Surface-modified serpentine powders with an average size of 1.0 μm were dispersed into mineral base oil to improve the lubricating properties of oil, as well as to generate a thin tribofilm on the worn surface. SEM, TEM, nano-indentation and Stribeck testing were performed to study the morphology, microstructure, micromechanical properties and tribological behavior of the tribofilm, respectively. Results show that a nanocrystalline tribofilm, with a thickness of 500–600 nm, is formed on the worn surface under the lubrication of oil with 1.5 wt% serpentine. The film is mainly composed of Fe3O4, FeSi, SiO2, AlFe and Fe-C compound (Fe3C). A phenomenological model of the tribofilm generated by serpentine was developed based on the experimental results. The excellent mechanical properties, reinforced phase of embedded particles and porous structure of the tribofilm contribute to the reduction of friction and wear, especially in the case of boundary and mixed lubrication. 相似文献
18.
Q. Luo 《Tribology Letters》2010,37(3):529-539
To investigate the origin of running-in friction in unlubricated sliding wear, a magnetron sputtered multilayer coating TiAlN/VN
was tested on a ball-on-disc tribometer for a series of sliding durations from 10 to 1000 cycles, followed by careful observation
of the obtained worn surfaces using an field-emission gun scanning electron microscope. Three steps of friction variation
were found: (1) prior to wear particle generation, low initial friction coefficient was around 0.2–0.25 purely attributed
to the asperity contact; (2) then it increased steeply to a range of 0.4–0.5 in the first 100 cycles following the generation,
breaking and agglomeration of wear particles, and in particular the scaling-up of fish-scale-like tribofilm; (3) eventually
it approached to a steady-state value around 0.5 when the friction was governed by the viscous shearing of the tribofilm.
It is concluded that, under unlubricated sliding wear, the friction behaviour of transition metal nitride hard coating is
dominated by the viscous shearing of tribofilm adhesively bonding to the parent nitride coating. 相似文献
19.
R. Franz M. Lechthaler P. Polcik M. Rebelo de Figueiredo C. Mitterer 《Tribology Letters》2012,45(1):143-152
Nb1−x
Al
x
N hard coatings were synthesised by cathodic arc-evaporation with different Al contents to study its influence on the tribological
properties. Ball-on-disc tests at temperatures up to 700 °C were performed and the recorded coefficient of friction was generally
in the range from 0.8 to 1.0. Subsequent analysis of the coating wear track and the counterpart wear scar by optical profilometry
and Raman spectroscopy revealed details on the wear behaviour of the tested coatings. The best wear performance for the Nb-rich
coatings was in the temperature range of 300–500 °C, whereas at the maximum testing temperature the higher oxidation resistance
with increasing Al content was beneficial in terms of wear resistance. 相似文献
20.
Metal‐free amorphous carbon (a‐C:H) coatings with 15% hydrogen were deposited on bearing steel surfaces. The friction and wear performance of these specimens was characterised in oscillating sliding tests with a ball‐on‐flat geometry. Balls of four ceramic and four metallic materials were investigated in tests at room temperature. Special attention was paid to the effect of moisture by testing in dry, normal, and moist air. The effect of water vapour on the friction and wear of the a‐C:H coatings was quite different for the different counterbody materials. The wear was in all cases very low, with a coefficient of wear below 10−7 mm3/N m for most cases. The coefficient of friction was also very low, between 0.04 and 0.12 for most of the tests. The smallest wear and friction coefficients were found for oxide ceramics, while during tests against SiC and Si3N4 the coating was worn through during the test. The effects of counterbody material and the humidity of the surrounding air are discussed in terms of friction and wear mechanisms. 相似文献