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1.
The microstructural properties of WC-Co-Cr and WC-Co coatings deposited by high-velocity oxygen fuel (HVOF) and high-velocity
air fuel (HVAF) processes were investigated. The tribological behavior of the coatings was studied by means of pin-on-disk
tests. Microcracking of the HVOF sprayed WC-Co coatings did not allow preparation of suitable disks for wear tests. The wear
rates of the remaining coatings were determined, and wear tracks on the coatings and counterbodies were investigated by SEM.
The HVAF sprayed coatings showed greater sliding-wear resistance compared to the HVOF coatings. The prime wear mechanism in
the WC-Co HVAF coatings was adhesive wear. The cobalt matrix is lubricious, resulting in very low wear rates and low debris
generation. The main wear mechanisms in the WC-Co-Cr coatings were adhesive and abrasive wear. Adhesive wear results in coating
material dislodgments (i.e., “pullouts”) that become trapped in the contact zone and act as a third-body abrasive. Particle
pullout from the coating significantly increases the wear rate of the coated specimen. The HVAF/WC-Co-Cr coatings exhibited
better resistance to particle pullout, resulting in a considerably lower wear rate than the HVOF/WC-Co-Cr coatings. 相似文献
2.
In the present paper, aluminum bronze-alumina composite coatings have been applied on mild steel substrate using conventional plasma spray and a new route based on cold spray techniques. The microstructure, phase distribution, microhardness, adhesion strength and tribological behavior of the composite coatings, consisting of alumina reinforcing phase distributed in a bronze matrix, were studied. Ball-on-disk dry sliding wear tests, Rubber Wheel tests and Erosion tests were conducted to examine the tribological behavior of the composite coatings. The tribological properties of the bronze coatings were improved by the addition of alumina. Friction coefficient of coatings depends strongly on the reinforcing particles content and spraying process. Wear mechanisms of the composite coatings, such as ploughing and particle delamination, were considered. In the case of abrasive wear test, the wear rate was greatly reduced due to the reinforcing ceramic particles. Relationships between size and volume fraction of the ceramic reinforcement Al2O3 and the wear rate are discussed. On the other hand, erosion wear behavior of coatings with higher bronze content showed the best results. 相似文献
3.
Yanchun Dong Dianran Yan Jining He Xiangzhi Li Jianxin Zhang 《Journal of Thermal Spray Technology》2006,15(3):323-328
Ceramic-metal composite (CMC) coatings were deposited on the surface of Fe-0.14–0.22 wt.% C steel by plasma spraying of self-reacting
Fe2O3−Al composite powders. The dry sliding friction and wear character of the CMC coatings are investigated in this paper. The
wear resistance of the CMC coatings was significantly better than that of Al2O3 coatings under the same sliding wear conditions. The tough metal, which is dispersed in the ceramic matrix, obviously improved
the toughness of the CMC coatings. Wear mechanisms of the CMC coatings were identified as a combination of abrasive and adhesive
wear. 相似文献
4.
E. Sánchez E. Bannier M. D. Salvador V. Bonache J. C. García J. Morgiel J. Grzonka 《Journal of Thermal Spray Technology》2010,19(5):964-974
WC-12%Co coatings were deposited by atmospheric plasma spraying using conventional and nanostructured powders and two secondary
plasmogenous gases (He and H2). Coating microstructure and phase composition were characterized using scanning electron microscopy (SEM), transmission
electron microscopy (TEM), and x-ray diffraction techniques (XRD) techniques. This study examined wear and friction properties
of the coatings under dry friction conditions. SEM was used to analyze abraded surface microstructure. Coating microhardness
and fracture toughness were also determined. All coatings displayed strong decarburization as a result of WC decomposition,
which gave rise to the formation of secondary phases (W2C and W). A very fine undissolved WC crystalline dispersion coexisted with these new phases. TEM observation confirmed that
the matrix was predominantly amorphous and filled with block-type, frequently dislocated crystallites. Wear was observed to
follow a three-body abrasive mechanism, since debris between the ball and the coating surface was detected. The main wear
mechanism was based on subsurface cracking, owing to the arising debris. WC grain decomposition and dissolution were concluded
to be critical factors in wear resistance. The level of decomposition and dissolution could be modified by changing the plasmogenous
gas or feed powder grain size. The influence of the plasmogenous gas on wear resistance was greater than the influence of
feedstock particle size. 相似文献
5.
A. C. Savarimuthu H. F. Taber I. Megat J. R. Shadley E. F. Rybicki W. C. Cornell W. A. Emery D. A. Somerville J. D. Nuse 《Journal of Thermal Spray Technology》2001,10(3):502-510
Tungsten carbide (WC) thermal spray coatings have gained increased acceptance for commercial aircraft applications driven
by the desire to replace chromium electroplate due to environmental and economic considerations. In order to confidently replace
electroplated chrome with WC thermal spray coatings in aircraft applications, the coatings must demonstrate fatigue and wear
characteristics as good as or better than those of electroplated chrome. Previous research in this area has shown that the
fatigue life of the WC thermal spray coatings can be improved by inducing compressive residual stresses in the coating. This
paper compares the wear characteristics of several types of WC thermal spray coatings with those of electroplated chrome in
sliding wear tests using the “block-on-ring” procedures described in the ASTM G77 standard. Wear results are interpreted in
terms of coating residual stresses and in terms of x-ray diffraction (XRD) and scanning electron microscope (SEM) analyses. 相似文献
6.
A comparative study of tribological behavior of plasma and D-gun sprayed coatings under different wear modes 总被引:3,自引:0,他引:3
Sundararajan G. Prasad K. U. M. Rao D. S. Joshi S. V. 《Journal of Materials Engineering and Performance》1998,7(3):343-351
In recent years, thermal sprayed protective coatings have gained widespread acceptance for a variety of industrial applications.
A vast majority of these applications involve the use of thermal sprayed coatings to combat wear. While plasma spraying is
the most versatile variant of all the thermal spray processes, the detonation gun (D-gun) coatings have been a novelty until
recently because of their proprietary nature. The present study is aimed at comparing the tribological behavior of coatings
deposited using the two above techniques by focusing on some popular coating materials that are widely adopted for wear resistant
applications, namely, WC-12% Co, A12O3, and Cr3C2-MCr.
To enable a comprehensive comparison of the above indicated thermal spray techniques as well as coating materials, the deposited
coatings were extensively characterized employing microstructural evaluation, microhardness measurements, and XRD analysis
for phase constitution. The behavior of these coatings under different wear modes was also evaluated by determining their
tribological performance when subjected to solid particle erosion tests, rubber wheel sand abrasion tests, and pin-on-disk
sliding wear tests. The results from the above tests are discussed here. It is evident that the D-gun sprayed coatings consistently
exhibit denser microstructures and higher hardness values than their plasma sprayed counterparts. The D-gun coatings are also
found to unfailingly exhibit superior tribological performance superior to the corresponding plasma sprayed coatings in all
wear tests. Among all the coating materials studied, D-gun sprayed WC-12%Co, in general, yields the best performance under
different modes of wear, whereas plasma sprayed Al2O3 shows least wear resistance to every wear mode. 相似文献
7.
A selection of WC-Co and Cr3C2-25%NiCr coatings deposited by plasma spraying and high velocity oxygen fuel (HVOF) were tested. The microstructures of the
coatings were characterized, and their mechanical properties were assessed using Knoop microindentation procedures. The coatings
were also subjected to various wear tests. All of the coatings were at least 200 μm thick and were deposited onto stainless
steel substrates. The wear tests simulated abrasion, cavitation wear, sliding wear, and particle erosion wear.
In this first part of a two-part contribution, the microstructures of the coatings are characterized and a discussion on the
evaluation of mechanical properties from the microindentation response is presented. The nature of microhardness testing as
applied to thermal spray coatings is evaluated as a means of assessing resistance to plastic flow, elasticity, and brittleness.
In Part 2, the results of the various wear simulations are reported, and the utility of microhardness as an indicator of wear
resistance is examined. 相似文献
8.
A selection of WC-Co and Cr3C2-25%NiCr coatings produced by plasma spray and high velocity oxygen fuel (HVOF) deposition techniques were subjected to various
wear tests designed to simulate abrasion, cavitation, sliding, and particle erosion type wear mechanisms. All of the coatings
were at least 200 μm thick and were deposited onto stainless steel substrates. In Part 1 of this contribution, the microstructures
of the coatings were characterized and their mechanical properties were assessed using microindentation procedures. In this
second part of the article, the behavior of the coatings when subjected to the various wear tests is reported and the utility
of microhardness testing as an indication of relative wear resistance is discussed. It is shown that correctly performed,
appropriate microhardness measurements are a good indication of abrasion resistance and sliding wear resistance, and also
correlate well with cavitation resistance in Cr3C2-NiCr. The measurements were less useful for predicting erosion resistance for both Cr3C2-NiCr and WC-Co, however, and for abrasion resistance when WC-Co was ground against SiC. Here the contribution of micromechanisms
involving fracturing and brittle failure is greater than that indicated by the coating microhardness, which is essentially
a measurement of resistance to plastic deformation under equilibrium conditions. 相似文献
9.
Ti-doped diamond like carbon films were deposited on both untreated and plasma nitrided Ti6Al4V alloy using Closed Field Unbalanced Magnetron Sputtering (CFUMBS) method and their tribological properties were evaluated by conducting sliding wear conditions. The influence of the nitrided layer on tribological behavior of Ti-DLC films was studied by means of XRD, SEM, scratch tester, microhardness tester and pin-on-disc tribotester. The microhardness results pointed out that the duplex treatment dramatically increased the surface hardness and reduced the plastic deformation of the alloy. Wear tests showed that Ti-DLC coatings on both untreated and nitrided surfaces caused a reduction in the coefficient of friction. The reason of the reduction in the coefficient of friction was found to be the formation of transfer film between the sliding surfaces. Wear rates demonstrated that wear resistance of duplex treated (Ti-DLC coating after nitriding) Ti6Al4V alloy was significantly improved. 相似文献
10.
P. Suresh Babu D. S. Rao G. V. N. Rao G. Sundararajan 《Journal of Thermal Spray Technology》2007,16(2):281-290
The detonation spraying is one of the most promising thermal spray variants for depositing wear and corrosion resistant coatings.
The ceramic (Al2O3), metallic (Ni-20 wt%Cr) , and cermets (WC-12 wt%Co) powders that are commercially available were separated into coarser
and finer size ranges with relatively narrow size distribution by employing centrifugal air classifier. The coatings were
deposited using detonation spray technique. The effect of particle size and its distribution on the coating properties were
examined. The surface roughness and porosity increased with increasing powder particle size for all the coatings consistently.
The feedstock size was also found to influence the phase composition of Al2O3 and WC-Co coatings; however does not influence the phase composition of Ni-Cr coatings. The associated phase change and %porosity
of the coatings imparted considerable variation in the coating hardness, fracture toughness, and wear properties. The fine
and narrow size range WC-Co coating exhibited superior wear resistance. The coarse and narrow size distribution Al2O3 coating exhibited better performance under abrasion and sliding wear modes however under erosion wear mode the as-received
Al2O3 coating exhibited better performance. In the case of metallic (Ni-Cr) coatings, the coatings deposited using coarser powder
exhibited marginally lower-wear rate under abrasion and sliding wear modes. However, under erosion wear mode, the coating
deposited using finer particle size exhibited considerably lower-wear rate. 相似文献
11.
Z. Y. Pan Y. Wang X. W. Li C. H. Wang Z. W. Zou 《Journal of Thermal Spray Technology》2012,21(5):995-1010
This paper reports studies into the effect of submicron and nano SiC particles on microstructure, phase composition, hardness, erosion wear, and scratch behavior of Al2O3-20wt.%8YSZ (ZrO2 + 8 wt.% Y2O3) coatings fabricated by atmospheric plasma spraying. The failure mode of erosion wear and scratch for coatings was established and analyzed. The hardness, density, erosion wear, and anti-scratch resistance of coatings fabricated from plasma treating feedstocks were higher than that of coatings made from sintering feedstocks. The erosion wear rate of coatings with SiC was evidently decreased, and there was some small debris on worn surface with characteristic of translamellar fracture. The spallation, fracture, plough, and cracking were main failure mechanism for coatings. In the scratch process, the critical load of coating with SiC was increased. The crack growth resistance of coatings was analyzed from crack length at end of scratch test. 相似文献
12.
E. M. Ruiz-Navas N. Antón E. Gordo R. Navalpotro F. Velasco 《Journal of Materials Engineering and Performance》2001,10(4):479-483
A ferritic stainless steel has been manufactured through the powder metallurgy (P/M) route: uniaxial pressing and sintering.
The sintering process was carried out in vacuum, at 1215 °C for 30 min. After sintering, materials showed nearly 90% of density.
A complete metallographic study was carried out using optical microscopy and scanning electron microscopy (SEM). Wear behavior
was evaluated using a “pin on disk” test according to ASTM Standard G99. Eight test conditions were studied, varying the load
(5 and 10 N), the speed (0.1 and 0.4 m/s), and the counter-material (chromium steel and a martensitic stainless steel). The
sliding distance was 400 m, and tests were carried out on polished materials, with less than 30% of relative humidity. Moreover,
wear tracks were observed by SEM in order to understand the wear processes involved, which depend mainly on the counter-material. 相似文献
13.
THERMAL SPRAYING provides a large range ofcoatings,which increase the wear resistance ofsubstrates[1].One of the major coating families is thecermet,composed of hard ceramic particles with ametallic binder.The most commonly used cermetcoatings in industrial applications are based on eitherthe WC-Co or the Cr3C2-Ni(Cr)systems with WC-17wt%Co and Cr3C2-25wt%Ni(Cr)being typicalcompositions[2,3].Although WC-Co deposits are hardand wear resistant at ambient temperatures their rangeof ap… 相似文献
14.
R. R. Chromik H. W. Strauss T. W. Scharf 《JOM Journal of the Minerals, Metals and Materials Society》2012,64(1):35-43
In situ tribometry, the study of real-time friction and wear processes occurring at “buried” sliding interfaces, was used to examine
fundamental changes to structure and chemistry of solid lubricant and hard coatings. In situ techniques of optical microscopy and Raman spectroscopy were used to observe interfacial sliding dynamics and identify near-surface
structural/chemical changes, respectively. Third-body physical and chemical processes, such as thickening, thinning, loss
of transfer films, generation of wear debris, and sliding-induced chemical changes, were identified for sapphire sliding against
Ti-Si-C, nanocrystalline diamond (NCD), and titanium- and tungsten-doped diamond-like carbon (DLC) coatings. These processes
observed by in situ methods were also used to explain why friction and wear behavior changed with coating composition, properties or test conditions. 相似文献
15.
Nanostructured alumina (Al2O3) and nanostructured cermet coatings containing alumina dispersed in a FeCu or FeCuAl matrix, were deposited by atmospheric plasma spraying (APS) from nanostructured powders. These coatings were characterized by SEM, EDAX, TEM, XRD and nanoindentation. Friction and wear behaviour were investigated by sliding and abrasion tests. TEM and XRD revealed that a nanostructuring was retained in the APS deposited coatings.The nanostructured ceramic and cermet coatings were compared in terms of coefficient of friction and wear resistance. Nanostructured cermet coatings appeared to offer a better wear resistance under sliding and abrasion tests than nanostructured Al2O3 coatings. The role of Fe, Cu, and Al additions to the Al2O3 coatings on friction and wear behaviour, was investigated.In the case of FeCu- and FeCuAl-based cermet coatings containing alumina, though the starting material consist of only two compounds, the coatings contain up to four different phases after plasma spraying. The mechanical properties of these different phases namely crack sensitivity and elasto-plastic deformation was determined by nanoindentation. The failure mechanisms were investigated and an attempt was made to establish a ‘structure-property’ relationship. It was shown that an appropriate balance between hard and soft phases results in optimum tribological properties of the nanostructured cermet coatings. 相似文献
16.
《Surface & coatings technology》2001,135(2-3):118-125
Tribological properties of MoSi2–MoS2 coatings coupling with SAE52100 steel were tested under reciprocating sliding. Effects of normal load, sliding speed and MoS2 content on the coatings tribological properties were studied. Worn surfaces of the coatings were analyzed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The friction coefficient of the coatings was approximately 0.45 and a little lower than that of the monolithic MoSi2. The friction did not vary with the sliding time, sliding speed and load. Coating with 12 wt.% MoS2 had the lowest friction. Wear rate of the coatings increased with the sliding speed and normal load and was higher than that of the monolithic MoSi2. Wear rate of the coatings did not vary with MoS2 content. Worn surface of the coatings and the coupling steel ball was covered by a SiO2 and MoO3 wear debris layer. Wear mechanism of the coatings was microfracture. 相似文献
17.
S. G. Jia P. Liu F. Z. Ren B. H. Tian M. S. Zheng G. S. Zhou 《Metals and Materials International》2007,13(1):25-30
By means of a vacuum induction furnace, a Cu−Ag−Cr alloy was produced. The electrotribological property and mechanism of the
Cu−Ag−Cr alloy wear studied via wear property tests, scanning electron microscope (SEM), energy dispersive X-ray spectrum
(EDS) and transmission electron microscopy (TEM). Wear tests were conducted with a specially designed sliding wear tester,
which simulated the tribological conditions of sliding current collectors on contact wires in a railway system. The alloy
wire was slid against a copperbased powder metallurgy strip under non-lubricated conditions. The results showed that the wear
rate of Cu−Ag−Cr alloy increases as the sliding speed increases under a normal load. Adhesive wear, abrasive wear, and electrical
erosion wear are the governing wear mechanisms under the electrical current sliding processes. Under the same conditions,
the wear resistance of the Cu−Ag−Cr alloy is 2–3 times that of the Cu−Ag alloy. 相似文献
18.
Tribological properties of TiC-Fe coatings obtained by plasma spraying reactive powders 总被引:1,自引:0,他引:1
Titanium carbide-based coatings have been considered for use in sliding wear resistance applications. Carbides embedded in
a metal matrix would improve wear properties, providing a noncontinuous ceramic surface. TiC-Fe coatings obtained by plasma
spraying of spray-dried TiC-Fe composite powders containing large and angular TiC particles are not expected to be as resistant
as those containing TiC particles formed upon spraying. Coatings containing 60 vol% TiC dispersed in a steel matrix deposited
by plasma spraying reactive micropellets, sintered reactive micropellets, and spray-dried TiC-Fe composite powders are compared.
The sliding wear resistance of these coatings against steel was measured following the test procedure recommended by the Versailles
Advanced Materials and Standards (VAMAS) program, and the inherent surface porosity was evaluated by image analysis. Results
show that, after a 1-km sliding distance, TiC-Fe coatings obtained after spraying sintered reactive powders exhibit scar ring
three times less deep than sprayed coatings using spray-dried TiC-Fe composite powders. For all coatings considered, porosity
is detrimental to wear performance, because it generally lowers the coating strength and provides cavities that favor the
adhesion of metal. However, porosity can have a beneficial effect by entrapping debris, thus reducing friction. The good wear
behavior of TiC-Fe coatings manufactured by plasma spraying of sintered reactive powders is related to their low coefficient
of friction against steel. This is due to the microstructure of these coatings, which consists of 0.3 to 1 μm TiC rounded
particles embedded in a steel matrix.
Presented at the International Conference on Metallurgical Coatings and Thin Films, ICMCTF-92, Apr 6–10, 1992, San Diego. 相似文献
19.
In present paper the influence of the tungsten carbide (WC) particle addition on the microstructure, microhardness and abrasive wear behaviour of flame sprayed Co-Cr-W-Ni-C (EWAC 1006) coatings deposited on low carbon steel substrate has been reported. Coatings were deposited by oxy-acetylene flame spraying process. Wear behaviour of coatings was evaluated using pin on flat wear system against SiC abrasive medium. It was observed that the addition of WC particle in a commercial Co-Cr-W-Ni-C powder coating increases microhardness and wear resistance. Wear behaviour of these coatings is governed by the material parameters such as microstructure, hardness of coating and test parameters (abrasive grit size and normal load). Addition of WC in a commercial powder coating increased wear resistance about 4-9 folds. WC modified powder coatings showed better wear resistance at high load. Heat treatment of the unmodified powder coatings improved abrasive wear resistance while that of modified powder coating deteriorated the wear resistance. SEM study showed that wear of coatings largely takes place by microgroove, crater formation and scoring. Electron probe micro analysis (E.P.M.A.) of unmodified and WC modified powder coating was carried out for composition and phase analysis. 相似文献
20.
I. Ozdemir C. Tekmen Y. Tsunekawa T. Grund 《Journal of Thermal Spray Technology》2010,19(1-2):384-391
In this study, mechanically alloyed Al-12Si/TiB2/h-BN composite powder was deposited onto aluminum substrates by atmospheric plasma spraying. Wear performance of the coating was investigated with respect to the structural evolution of the composite powder coating. Non-lubricated ball-on-disk tests were used to examine the wear resistance of the coatings. The worn surfaces were examined using scanning electron microscopy and energy dispersive spectroscopy to elucidate the wear mechanisms operating at the sliding interface. It has been observed that TiB2 and in situ formed AlN and Al2O3 phases in combination with h-BN solid lubricant strongly affect the wear performance of the coating. 相似文献