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1.
《Wear》1997,212(2):244-253
The usefulness of WCCo cermets as wear resistant material for coatings is determined by the cladding technique employed. This paper compares the features of an 83% WCCo coating on an AISI 1043 steel substrate using two different application techniques: plasma spraying and laser cladding. Results show significantly less porosity, improved coating hardness and better layer-substrate adherence in laser cladded than in plasma sprayed coatings. This causes them to have different wear behaviour which was determined using a method developed on the basis of the PV factor theory using sliding linear contact of flat-cylinder type. The method proved that wear rate (Vd′) is directly proportional to the product of coefficient of friction (μ), load (C) and applied speed (V), Vd′ = KμCV, where proportionality constant, K, is different for every material and depends on conditions such as lubrication, temperature, etc. To study wear behaviour, laser cladded and plasma sprayed 83% WC-Co coatings, under extreme lubrication, were placed against a hardened and tempered AISI 1043 steel, at different load and sliding speed rates. As a result constant K was estimated for each coating. The tests also showed that wear rate in laser deposited coatings is approximately 34% lower than in plasma sprayed coatings. 相似文献
2.
The work presents the results of investigating the influence of the ion concentration in the WC?Co electrode materials on the structure and properties of the coatings deposited by electrospark deposition (ESD) on low-carbon steel. It has also been shown that iron concentration affects the character of mass transfer and thickness of the deposited coating. The phase composition, roughness, and wear resistance of the obtained coatings were studied under the conditions of the dry microabrasive rubbing. The increased iron concentration in the electrode materials was found to intensify the decarbidization of tungsten carbide at ESA. 相似文献
3.
Mechanical and tribological properties of Cr–Nb double-glow plasma coatings deposited on Ti–Al alloy
Xiangfei Wei Pingze Zhang Dongbo Wei Hongyuan Zhao Chun Wang Tomasz Liskiewicz 《Tribology - Materials, Surfaces & Interfaces》2017,11(2):98-106
Double-glow plasma (DGP) coatings are recommended for metallic components to mitigate the damage induced by complex working conditions in previous studies. In this paper, Nb-rich (Cr–Nb4) and Cr-rich (Cr4–Nb) -alloyed layers were formed onto the Ti–Al substrate via a DGP process to enhance its wear resistance. Scratch and Nano-indentation tests were used to evaluate the mechanical properties of the coatings. The tribological behaviour of the coatings were investigated using a pin-on-disc tribometer by rubbing against the GCr15 ball. Results from surface analysis techniques showed that the coatings mainly comprised Cr, Nb and Cr2–Nb phases, and were well bonded to the substrate. The hardness of the Cr–Nb4 coating was 11.61GPa and the Cr4–Nb coating was 9.66 GPa which all higher than that of the uncoated Ti–Al which was 5.65 GPa. However, the critical load of the Cr4–Nb coating ~21.64 was higher than that of the Cr–Nb4 coating ~17.6. And the specific wear rate of Cr–Nb4 coating, Cr4–Nb coating and uncoated Ti–Al were 3.54 × 10?4, 0.01 × 10?4 and 1.53 × 10?4mm3 N?1 m?1, respectively. The low-wear mechanism of the coatings is discussed in detail in this paper. 相似文献
4.
NiCr–Al2O3–SrSO4–Ag self-lubricating composites were prepared by powder metallurgy method and the tribological properties of composites were evaluated by a ball-on-disk tribometer against alumina ball at wide temperature range from the room temperature to 1,000 °C in air. The linear coefficient of thermal expansion was evaluated for investigation of thermal stability of composites. The tribo-chemical reaction films formed on the rubbing surfaces and their effects on the tribological properties of composites at different temperatures were addressed according to the surface characterization by SEM, XRD, and XPS. The results show that the NiCr–Al2O3 composite with addition of 10 wt% SrSO4 and 10 wt% Ag exhibits satisfying friction and wear properties over the entire temperature range from room temperature to 1,000 °C. The composition of the tribo-layers on the worn surfaces of the composites is varied at different temperatures. The synergistic lubricating effect of SrAl4O7, Ag, and NiCr2O4 lubricating films formed on worn surfaces were identified to reduce the friction coefficient and wear rate from room temperature to 800 °C. Meanwhile, at 1,000 °C, the SrCrO4 and NiAl2O4 was formed on the worn surfaces during sliding process, combining with the NiCr2O4, Al2O3, Cr2O3, Ag, and Ag2O, which play an important role in the formation of a continuous lubricating film on the sliding surface. 相似文献
5.
K. Bonny P. De Baets J. Quintelier J. Vleugels D. Jiang O. Van der Biest B. Lauwers W. Liu 《Tribology International》2010,43(1-2):40-54
Flat samples of WC–Co hardmetals with 6–12 wt%Co were surface finished by grinding, polishing and wire-electro-discharge machining (EDM). Comparative dry reciprocating sliding experiments against WC–6 wt%Co pins were performed using a Plint TE77 tribometer. Tribological characteristics were recorded online. Wear surfaces were characterized by surface scanning topography and scanning electron microscopy. Wire-EDM’ed samples exhibited higher friction and wear compared to ground and polished equivalents. This trend was correlated to X-ray diffraction measurements revealing tensile residual surface stresses in WC after wire-EDM contrary to compressive surface stresses after grinding and polishing. However, finer executed EDM reduces friction and wear significantly. 相似文献
6.
A series of high carbon Fe–Cr–C hardfacing alloys were produced by gas tungsten arc welding (GTAW). Chromium and graphite alloy fillers were used to deposit hardfacing alloys on ASTM A36 steel substrates. Depending on the four different graphite additions in these alloy fillers, this research produced hypereutectic microstructures of Fe–Cr phase and (Cr,Fe)7C3 carbides on hard-facing alloys. The microstructural results indicated that primary (Cr,Fe)7C3 carbides and eutectic colonies of [Cr–Fe+(Cr,Fe)7C3] existed in hardfacing alloys. With increasing the C contents of the hardfacing alloys, the fraction of primary (Cr,Fe)7C3 carbides increased and their size decreased. The hardness of hardfacing alloys increased with fraction of primary (Cr.Fe)7C3 carbides. Regarding the abrasive characteristics, the wear resistance of hardfacing alloys were related to the fraction of primary (Cr,Fe)7C3 carbides. The wear mechanism was also dominated by the fraction of primary (Cr,Fe)7C3 carbides. Fewer primary carbides resulted in continuous scratches worn on the surface of hardfacing alloy. In addition, the formation of craters resulted from the fracture of carbides. However, the scratches became discontinuous with increasing fraction of the carbides. More primary carbides can effectively prevent the eutectic colonies from the damage of abrasive particles. 相似文献
7.
8.
Cr–N coatings were deposited on austenitic stainless steel, X6CrNiTi18-10, by means of the cathodic arc evaporation method at three substrate temperatures: 200 °C, 350 °C and 500 °C. All coatings were found to have a composition of Cr(N), CrN and Cr2N. The substrate temperature was found to have an influence on the hardness and Young's modulus of the Cr–N coatings. The investigation of nanocrystalline Cr–N coatings resistance to cavitation was performed in a cavitation tunnel with a slot cavitator and tap water as the medium. The estimated cavitation resistance parameters of the coatings were the incubation period of damage and total mass loss. It was found that the optimal coating cavitation resistance was deposited at 500 °C. The incubation period for the 500 °C deposition coating was the same as that of the uncoated X6CrNiTi18-10 steel, but the total mass loss was significantly lower than on the uncoated specimen. The scanning electron microscope analysis indicated that the damage process of the Cr–N coating mainly originates from the plastic deformation of the steel substrate–hard coating system, which appears by “micro-folding” of the surface. An increase of tensile stresses at the top of micro-folds initiates micro-cracks and delamination of Cr–N coating. The results of the investigation and the analysis indicate that the factors mainly responsible for cavitation resistance of the steel substrate/hard coating system are resistant to plastic deformation of the total system and coating adhesion. 相似文献
9.
Satpal Sharma 《The International Journal of Advanced Manufacturing Technology》2012,61(9-12):889-900
In the present investigation, Ni–WC composite powder was modified with the addition of CeO2 in order to form a new composition of Ni–WC–CeO2. The Ni–WC and Ni–WC–CeO2 compositions were used for coating deposition by high-velocity oxy-fuel (HVOF) spraying process so as to study the effect of CeO2 addition on microstructure, distribution of various elements, hardness, formation of new phases, and abrasive wear behavior. Further, the effect of load, abrasive size, sliding distance, and temperature on abrasive wear behavior of these HVOF-sprayed coatings was investigated by response surface methodology. To investigate the abrasive wear behavior of HVOF-sprayed coatings four factors such as load, abrasive size (size in micrometers), sliding distance (meters), and temperature (°C) with three levels of each factor were investigated. Analysis of variance was carried out to determine the significant factors and interactions. Investigation showed that the load, abrasive size, and sliding distance were the main significant factors while load and abrasive size, load and sliding distance, abrasive size and sliding distance were the main significant interactions. Thus an abrasive wear model was developed in terms of main factors and their significant interactions. The validity of the model was evaluated by conducting experiments under different wear conditions. A comparison of modeled and experimental results showed 4–9% error. The abrasive wear resistance of coatings increases with the addition of CeO2. This is due to increase in hardness with the addition of CeO2 in Ni–WC coatings. 相似文献
10.
A number of WC–Ni based cemented carbide grades with distinctive binder contents were tested with the goal to evaluate their
dry reciprocating sliding friction and wear behaviour against WC–6 wt.%Co cemented carbide using a Plint TE77 tribometer and
distinctive normal contact loads. The generated wear tracks were analysed by scanning electron microscopy and quantified volumetrically
using surface scanning topography. The experimental results revealed one WC–Ni grade with superior wear performance. 相似文献
11.
K. Bonny P. De Baets J. Vleugels A. Salehi O. Van der Biest B. Lauwers W. Liu 《Tribology Letters》2008,30(3):191-198
ZrO2-based composites with WC addition can be successfully machined by electrical discharge machining (EDM) in demineralised water.
ZrO2 composites with 40 vol.% WC were produced from nanocrystalline and micrometre sized WC starting powders in order to compare
their tribological behaviour. Friction and wear data are obtained on wire-EDM’ed ZrO2–WC composite flats sliding against a WC–Co cemented carbide pin using a small-scale pin-on-plate testing rig. Correlations
between wear volume, wear rate and friction coefficient on the one hand and material properties and test conditions on the
other hand were elucidated. The experimental results revealed that the grain size of the electro-conductive WC-phase exhibits
a strong influence on the friction and wear behaviour of the ZrO2-based composite. 相似文献
12.
Transition metal dichalcogenides belong to the more developed class of materials for solid lubrication. However, the main limitation of these materials is the detrimental effect of air humidity causing an increase in the friction. In previous works, molybdenum diselenide has been shown to be a promising coating retaining low friction even in very humid environment. In this study, Mo–Se–C films were deposited by sputtering from a C target with pellets of MoSe2. Besides the evaluation of the chemical composition, the structure, the morphology, the hardness and the cohesion/adhesion, special attention was paid to the tribological characterization.The C content varied from 29 to 68 at.% which led to a progressive increase of the Se/Mo ratio. As a typical trend, the hardness increases with increasing C content. The coatings were tested at room temperature with different air humidity levels and at temperatures up to 500 °C on a pin-on-disc tribometer. The friction coefficient of Mo–Se–C coatings increased with air humidity from ~0.04 to ~0.12, while it was as low as 0.02 at temperature range 100–250 °C. The coatings were very sensitive to the elevated temperature being worn out at 300 °C due to adhesion problems at coating–titanium interface. 相似文献
13.
The effect of 10 wt% VC addition on the friction and sliding wear response of WC–12 wt% Co cemented carbides produced by spark plasma sintering (SPS) was studied. The SPS of WC–12 wt% Co alloys with and without 10 wt% VC, at 1100 and 1130°C, respectively, yielded dense materials with minimal porosity. No eta phase was found in any of the alloys. The WC–12 wt% Co–10 wt% VC alloy showed the formation of a hard WV4C5 phase, which improved the alloy's hardness. Friction and dry sliding wear tests were done using a ball-on-disk configuration under an applied load of 10 N and sliding speed of 0.26 m.s?1, and a 100Cr-steel ball was used as the counterface. A significant improvement in the sliding wear response of the harder and more fracture tough WC–12 wt% Co–10 wt% VC alloy compared to the WC–12 wt% Co alloy was found. Analysis of the worn surfaces by scanning electron microscopy showed that the wear mechanisms included plastic deformation, preferential binder removal, adhesion, and carbide grain cracking and fragmentation. 相似文献
14.
《Wear》2002,252(7-8):566-579
A series of macroparticle-free TiN, TiCxN(1−x) and TiC coatings were deposited on 316 austenitic stainless steel using a titanium target in a filtered arc deposition system (FADS) and reactive mixtures of N2 and/or CH4 gases. The surface topography, chemical composition and microstructure of these coatings were characterised by optical microscopy (OM), atomic force microscopy (AFM), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The microhardness has been measured and the adhesion of the coatings has been evaluated. Further, the wear and friction behaviour of the coatings were assessed under controlled test conditions in a pin-on-disc tribometer.The results show a significant increase in surface roughness, microhardness and wear resistance as the CH4:N2 gas flow rate ratio is increased. The composition of the coatings was strongly dependent on reactive gas flow rate during deposition. Surface particles were observed on high carbon content coatings and subsequently determined to be carbonaceous particles by using OM, AFM and EDS. At lowest load (10 N), all coatings exhibited low friction and wear. At loads of 15 and 25 N, the higher carbon content TiCN and TiC coatings showed a much lower friction and wear compared to TiN and low carbon TiCN. 相似文献
15.
Transition metal dichalcogenides (TMD) have been one of the best alternatives as low friction coatings for tribological applications, particularly in dry and vacuum environments. However, besides their deficient behavior in humid containing atmospheres, their extensive application has also been restricted due to their low load-bearing capacity. In order to overcome these problems, recently the alloying with C has been tried with the expectation of simultaneously improving the coatings hardness and reaching sliding contacting phases more convenient for achieving low friction in humid environments.The practical application of this concept was extensively studied with the W–S–C system, with the C addition being achieved either by reactive or co-sputtering processes. The best tribological results were obtained by co-sputtering from a C target embedded with an increasing number of WS2 pellets. Excellent results were reached from the more than one order of magnitude increase in the coatings hardness up to friction coefficients which are close to those of the references of self-lubricating coatings: TMD for dry or vacuum atmospheres or C-based coatings for terrestrial sliding conditions.Following the good results achieved with W–S–C system, other TMDs systems have been envisaged to be studied. The main focus was placed on the Mo–Se–C system.In this paper, the general comparison between W–S–C and Mo–Se–C coatings is presented. The main effort is pointed on the tribological behavior of both systems when tested by pin-on-disk against steel counterpart balls under different testing conditions: applied normal loads, temperatures and relative humidity of the atmospheres. Both coatings were deposited by co-sputtering from a C target with a varying number of TMD pellets which could lead to C contents in the films in the range from 30 up to 70 at.%. A Ti interlayer was interposed between the films and the substrates for improving the adhesion.Typically, W–S–C films are harder than Mo–Se–C films. From the tribological point of view, W–S–C films are more thermally stable than Mo–Se–C films although the friction coefficients of these last ones are lower when tested in humid containing atmospheres. 相似文献
16.
The effect of Al2O3 content on the mechanical and tribological properties of Ni–Cr alloy was investigated from room temperature to 1000 °C. The results indicated that NiCr–40 wt% Al2O3 composite exhibited good wear resistance and its compressive strength remained 540 MPa even at 1000 °C. The values obtained for flexural strength and fracture toughness at room temperature were 771 MPa, 15.2 MPa m1/2, respectively. Between 800 °C and 1000 °C, the adhesive and plastic oxide layer on the worn surface of the composite was claimed to be responsible for low friction coefficient and wear rate. 相似文献
17.
The microstructures and performance of Ni–WC (nickel–tungsten carbide) composite overlays deposited by plasma transferred arc welding are studied using a combination of microscopy, hardness, and wear testing. The Ni–WC overlays had microstructures consisting of γ-Ni dendrites, with interdendritic Ni-based eutectics, borides and carbides. Overlays which were produced with a low hardness Ni-alloy matrix contained a smaller fraction of interdendritic phases relative to the high hardness Ni-alloys.The dissolution of WC particles was observed following deposition of the MMCs, and this promoted the formation of secondary carbide phases. Ni-alloys with low carbon and low Cr content exhibited the least dissolution of WC. The Ni–WC overlays produced using these dilute alloys generally performed better in ASTM G65 wear tests. This was due to the increased fraction of retained WC phase, and the reduced fraction of brittle secondary carbide phases when the Ni-alloy contained no Cr. 相似文献
18.
Both plasma chromizing and carburization following plasma chromizing (duplex treatment) for Ti–Al–Nb alloy were performed,
respectively, and the microstructure, dynamic ultra-microhardness, and elastic modulus of the alloying layer were determined.
Using silicon nitride (Si3N4) balls as the counterface materials, dry sliding friction tests on the substrate, the chromized layer, and the duplex-treated
layer were completed by ball-on-disk tribometer at room temperature. The results indicated that the duplex-treated layer was
mainly composed of Cr23C6, Cr2Nb, pure chromium, and carbon phases, while the chromized layer consisted of Al8Cr5 and Cr2Nb phases. The ultra-microhardness of the duplex-treated layer was higher than that of the chromized layer, whereas the elastic
modulus of the duplex-treated layer was lower than that of the chromized layer. The friction coefficient of the duplex-treated
layer was about three times lower than that of the chromized layer, while the wear rate was one order of magnitude lower than
that of the chromized layer. 相似文献
19.
《Tribology - Materials, Surfaces & Interfaces》2013,7(3):125-131
AbstractIn the present study, the wear behaviour of Cu–Al2O3 composites and Cu–Al alloys has been investigated. The experiment involved casting of Cu–Al alloys with 0·37, 1, 2 and 3 wt-% of aluminium under inert gas atmosphere. The composites were produced by internal oxidation of alloys at 950°C for 10 h in presence of Fe2O3 and Al2O3 powders mixture. The microstructures of composites were studied using SEM and atomic force microscopy. To identify wear behaviour of specimens, dry sliding pin-on-disk wear tests were conducted according to ASTM G99-95a standard. The normal loads of 20, 30, and 40 N were applied on specimens during wear tests. The sliding speed and distances were selected as 0·5 m s–1 and 500, 1000 and 1500 m respectively. To specify the wear mechanisms, the worn surfaces of composites were examined by SEM equipped with EDX. According to wear test results, increasing applied load and sliding distance leads to more volume loss in all specimens. Composites represent better wear resistance in comparison to alloys. Additionally, increasing the volume fraction of alumina particles in composites enhances the wear resistance, especially under high applied load. The wear mechanisms are mainly abrasion, oxidation and delamination. 相似文献
20.
《Tribology - Materials, Surfaces & Interfaces》2013,7(1):13-20
AbstractLaser cladded coatings have been used extensively to extend the service life of components exposed to severe abrasive wear. One of the main wear resistant materials used in laser cladding is ceramic–metallic composite. Despite extensive use of this class of material, there is very limited knowledge regarding mechanical degradation mechanisms, such as cracking and plastic deformation, under different wear conditions. In this investigation a mixture of nickel alloy and tungsten carbide powders were used to deposit the coating. Two types of tungsten carbide powders with spherical and angular carbides were employed. The microstructures of the coatings were analysed thoroughly by optical microscopy, electron probe microanalysis and wavelength dispersive spectrometry. Failure and cracking mechanisms of laser cladded coatings under normal and tangential loading were systematically investigated using scratch testing. In the nickel alloy matrix, fine mixed secondary carbides were formed due to partial dissolution and formation of the secondary tungsten carbide during laser cladding. These secondary carbides were rich in chromium, tungsten and nickel and had a blocky and/or bar-like shape. Failure mechanisms associated with scratch testing were dependent on the microstructure and carbide morphology, applied stress and location of carbide particles with regard to the scratch groove. Owing to the high binder mean free path between the carbide particles, plastic deformation of the binder was the dominant failure mechanism. Additionally, partial or whole fragmentation of carbides, carbide/binder interface cracking and limited binder fracture were observed. 相似文献