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1.
In this paper, the tribological and electrochemical corrosion properties of Al 2O 3/polymer nanocomposite coatings were studied by using micro-hardness test, single-pass scratch test, abrasive wear test, and finally electrochemical technique such as potentiodynamic polarization measurement. The coatings containing Al 2O 3 nanoparticles showed improvement in scratch and abrasive resistance compared with that of polymer coating. The improvement in scratch and abrasive resistance is attributed to the dispersion hardening of Al 2O 3 nanoparticles in polymer coatings. Corrosion test results showed that the embedded Al 2O 3 nanoparticles in polymer matrix do not sacrifice the corrosion resistance of the polymer itself. 相似文献
2.
Plasma sprayed ceramic coatings are used in a number of industries in which surface modification of components to compare tribological properties is important: so hence, are evaluations of their tribological properties. This paper presents a study on the wear behaviour of three ceramic coatings — Al 2O 3, TiO 2 and Al 2O 3-TiO 2combination — in the load and speed ranges of 5 to 50 N, and 0.3 to 10 m/s, respectively, on which few data are available in the literature. The tests were carried out using a standard dry sand rubber wheel abrasion test and a pin-on-disc machine under dry sliding conditions. It was found that a stick-slip effect seems to occur at low sliding speeds, and transition takes place at a sliding speed of around 4 m/s. Of the three ceramic coatings, TiO 2 was found to be the most wear resistant, with the least friction coefficient, although it is less hard than the Al 2O 3 coatings. Scanning electron microscopy of the surface shows evidence of wear mechanisms such as plastic deformation, transfer-film formation, micro cracks, and grain pull-out in the coatings. 相似文献
3.
Nanocomposite coatings can endow a plated surface with various properties such as wear resistance, high-temperature corrosion protection, oxidation resistance, and self-lubrication. This work studies the corrosion and corrosive wear resistance of electroplated nickel nanocomposite coatings on Ti-6Al-4V alloy in a Hank's solution, adding various concentrations of an Al 2O 3 powder in plating solution, with particle diameters of 20–30 nm and 1 μm for comparisons. The experimental results showed that the content of Al 2O 3 incorporated into the electroplated nickel composite coating increased with the concentration of Al 2O 3 powder in the electroplating solution, and increasing the surface hardness, corrosion, and corrosive wear resistance of electroplated nickel micro- and nanocomposite coatings caused smearing of the nodule boundary and elimination of voids in the deposits. The Al 2O 3 nanoparticulates were embedded and distributed more uniformly than the Al 2O 3 microparticulates in the nickel matrix after a heat treatment of 400°C, producing a more continuous and dense coated composite layer on the Ti-6Al-4V substrate. This phenomenon is responsible for the Ni/Al 2O 3 composite coating with superior surface hardness, providing high corrosion resistance and corrosive wear protection to the Ti-6Al-4V alloy substrate in Hank's solution. 相似文献
4.
Tribological properties of TiO 2 coatings synthesized by micro-arc oxidation (MAO) on the surface of TC4 titanium alloys were investigated at the fretting
contact against 440C stainless steel in simulated body fluid (SBF). Fretting experiments were carried out by ball-on-flat
contact at various loads for 1 h, with an amplitude of 100 μm and a frequency of 5 Hz. Results show that MAO TiO 2 coatings presented good tribological properties with lower friction coefficient in SBF. Less wear volume was observed for
MAO TiO 2 coatings compared with that for TC4 alloy. At lower load, the wear mechanism of MAO TiO 2 coatings was dominated to abrasive wear. With an increase of normal load, however, fretting corrosion increased due to chemical
reactions with SBF, and therefore, fretting fatigue coexisting with abrasive wear became the predominant mode. 相似文献
5.
Nanostructured and conventional Al 2O 3-3 wt% TiO 2 coatings were deposited by atmospheric plasma spraying. The wear and friction properties of both coatings against a steel ball under dry friction conditions were examined. It was found that the wear resistance of the nanostructured Al 2O 3-3 wt% TiO 2 coating was superior to that of the corresponding conventional counterpart. The improvement in wear resistance of the nanostructured coating was attributed to its higher toughness and cohesion strength between splats. As for the nanostructured coating, the wear mechanism was mainly adhesion with micro-abrasion at low loads (20 N). At high loads (80 N), the wear of the nanostructured coating was controlled by plastic deformation and associated delamination along the splat boundaries, which was similar to that of the conventional coating at low loads. However, the failure of the conventional coating was predominantly brittle fracture within the splats and delamination between splats at high loads. 相似文献
6.
The effect of the sliding speed on friction and wear characteristics of plasma-sprayed ceramic coatings (Al 2O 3-13% TiO 2, ZrO 2-8% Y 2O 3, Al 2O 3-modified) was studied. Plasma-sprayed coatings are not hard and have high layered structure. Abrasion of coatings in the friction pair with steel and bronze counter-bodies occurs through brittle detachment conglomerated regions with low cohesive resistance. The modified coating (Al 2O 3) has the highest wear resistance and the lower coefficient of friction compared to the coatings (Al 2O 3-13% TiO 2, ZrO 2-8% Y 2O 3) in the studied velocity range (0.1–10 mm/s). Laser melting can be used as an efficient way of increasing the tribotechnical properties of plasma-sprayed oxide coatings. 相似文献
7.
ABSTRACT The study of laser cladding of 90Ti-10Al 2O 3, 90Ti-8Al 2O 3-2Zn and 90Ti-4Al 2O 3-6Zn coatings onto Ti-6Al-4V alloy, with intention to produce defect-less, high microhardness and wear resistant coating was carried out. The coatings were deposited onto Ti-6Al-4V alloy at 900 W laser power and 0.6 m/min laser scan speed. Microstructures and phase constituents of the developed coatings were investigated by using a scanning electron microscope (SEM) and X-ray diffractometer correspondingly. Vickers microhardness tester and pin-on-disk tribometer were employed to characterize microhardness and wear behaviour of the Ti-Al 2O 3/Zn coatings respectively. SEM was also used to examine the worn track. It was observed that 90Ti-10Al 2O 3 coating yielded optimal microhardness along with maximal wear resistance in comparison to the other coatings and Ti-6Al-4V alloy. It has been established that laser cladding of Ti-Al 2O 3 coating with Zn contents on Ti-6Al-4V alloy alleviates the formation of cracks, however, microhardness and wear properties are negatively affected. 相似文献
8.
In the present study, the abrasive wear characteristics of Al 2O 3/PA1010 composite coatings were tested on the turnplate abrasive wear testing machine. Steel 45 (quenched and low-temperature tempered) was used as a reference material. The experimental results showed that when the Al 2O 3 particles have been treated with a silane coupling agent (γ-aminopropyl-triethoxysilane), the abrasive wear resistance of Al 2O 3/PA1010 composite coatings has a good linear relationship with the volume fraction of Al 2O 3 particles in Al 2O 3/PA1010 composite coatings and the linear correlation coefficient is 0.979. Under the experimental conditions, the size of Al 2O 3 particles (40.5-161.0 μm) has little influence on the abrasive wear resistance of Al 2O 3/PA1010 composite coatings. By treating the surface of Al 2O 3 particles with the silane coupling agent, the distribution of Al 2O 3 particles in PA1010 matrix is more homogeneous and the bonding state between Al 2O 3 particles and PA1010 matrix is better. Therefore, the Al 2O 3 particles make the Al 2O 3/PA1010 composite coatings have better abrasive wear resistance than PA1010 coating. The wear resistance of Al 2O 3/PA1010 composite coatings is about 45% compared with that of steel 45. 相似文献
9.
AbstractZrN coating is an alternative candidate to replace the conventional TiN coating especially for high temperature oxidation resistance applications. ZrN coatings of varying thickness (1·5, 2·0, 2·5, 3·0 and 4·0 μm) were deposited on 316 stainless steel substrates by cathodic arc evaporation in a reactive nitrogen atmosphere. The influences of lamellae thickness on the microstructure, tribological and corrosive properties of the films were investigated. The coefficient of steady state friction of the films ranged from 0·213 to 0·659. The corrosion resistance of the coatings was tested in 1 N H 2SO 4 solution. The results indicate that the microstructure, wear and corrosion properties of the films were dependent on lamellae thicknesses and film structure. 相似文献
10.
The tribopairs of water hydraulic plunger pumps are usually operated under severe conditions, due to the poor lubrication of water and silt suspended in natural water. It is essential to identify the desired engineering materials and material combinations for designing water pumps. As the candidate materials of tribopairs, the tribological characteristics of different Al 2O 3-TiO 2 coatings combined with Si 3N 4 ceramics under silt-laden water and tap water lubrication were investigated. The Al 2O 3-TiO 2 coatings with different weight percentages of TiO 2 in a wide range from 3 to 100% were tested. The tribological characteristics of the various couple pairs were researched using a ring-on-ring test rig. The microstructures of the contact surfaces were analyzed with a scanning electron microscope before and after the test to study the wear mechanism. The experimental results indicate that the friction coefficient of the Al 2O 3-TiO 2/Si 3N 4 tribopairs increases with an increase in the percentage of TiO 2 content in the Al 2O 3-TiO 2 coating. However, the TiO 2 content does not present a clear relationship with the wear rate. Considering the friction and wear properties, Al 2O 3-13%TiO 2 is the preferred coating to use in water hydraulic pumps when sliding against Si 3N 4. 相似文献
11.
The tribological properties of part surfaces, namely their wear resistance and friction properties, are decisive in many cases
for their proper function. To improve surface properties, it is possible to create hard, wear-resistant coatings by thermal
spray technologies. With these versatile coating preparation technologies, part lifetime, reliability, and safety can be improved.
In this study, the tribological properties of the HVOF-sprayed coatings WC–17%Co, WC–10%Co4%Cr, WC–15% NiMoCrFeCo, Cr 3C 2–25%NiCr, (Ti,Mo)(C,N)–37%NiCo, NiCrSiB, and AISI 316L and the plasma-sprayed Cr 2O 3 coating were compared with the properties of electrolytic hard chrome and surface-hardened steel. Four different wear behavior
tests were performed; the abrasive wear performance of the coatings was assessed using a dry sand/rubber wheel test according
to ASTM G-65 and a wet slurry abrasion test according to ASTM G-75, the sliding wear behavior was evaluated by pin-on-disk
testing according to ASTM G-99, and the erosion wear resistance was measured for three impact angles. In all tests, the HVOF-sprayed
hardmetal coatings exhibited superior properties and can be recommended as a replacement for traditional surface treatments.
Due to its tendency to exhibit brittle cracking, the plasma-sprayed ceramic coating Cr 2O 3 can only be recommended for purely abrasive wear conditions. The tested HVOF-sprayed metallic coatings, NiCrSiB and AISI
316L, did not have sufficient wear resistance compared with that of traditional surface treatment and should not be used under
more demanding conditions. Based on the obtained data, the application possibilities and limitations of the reported coatings
were determined. 相似文献
12.
The effects of some anti-wear additives on the friction and wear behaviour of plasma-sprayed Cr 2O 3 coating were investigated using a block-on-ring tester at ambient conditions. The results show that zinc dialkyldithiophosphate (ZDDP), tricesyl phosphate (TCP) and tributyl phosphate (TBP) significantly reduce the wear of Cr 2O 3 coating lubricated by paraffin oil. Additive concentrations as well as sliding time have great influence on the wear. The friction coefficient varies slightly with test conditions. The analysis by XPS of worn surfaces indicates that the wear resistance of these additives is due to the formation of tribochemical reaction films by reacting with Cr 2O 3 coatings. 相似文献
13.
Six kinds of Ni60 alloy coatings with different percentage of Y2O3 were prepared by laser cladding. A metallurgical microscope was used to analyze the morphology of the cladding layer. Scanning electron microscopy and EDS energy spectrum analysis were used to characterize the microstructure and element segregation of the cladding layer. A Vickers microhardness tester was used to measure the hardness of the cladding layer. Finally, a friction and wear tester established the friction and wear properties of the cladding layer. The study results show that Y2O3 can significantly reduce the height of the cladding layer and increase the width of the cladding layer; it can also improve the structure refinement and element segregation of the cladding layer. The microhardness of the cladding layer is significantly improved compared to the Ni60 alloy coating without Y2O3, thereby enhancing the wear resistance of the coating. 相似文献
14.
Al 2O 3 and Cr 2O 3 coatings were deposited by atmospheric plasma spraying and their tribological properties dry sliding against copper alloy were evaluated using a block-on-ring configuration at room temperature. It was found that the wear resistance of Al 2O 3 coating was superior to that of the Cr 2O 3 coating under the conditions used in the present study. This mainly attributed to its better thermal conductivity of Al 2O 3 coating, which was considered to effectively facilitate the dissipation of tribological heat and alleviate the reduction of hardness due to the accumulated tribological heat. As for the Al 2O 3 coating, the wear mechanism was plastic deformation along with some micro-abrasion and fatigue-induced brittle fracture, while the failure of Cr 2O 3 coating was predominantly the crack propagation-induced detachment of transferred films and splats spallation. 相似文献
15.
ZrO 2–Y 2O 3 ceramic coatings were deposited on AISI 304 stainless steel by both a low-pressure plasma spraying (LPPS) and a laser-assisted plasma hybrid spraying (LPHS). Microstructure and tribological characteristics of ZrO 2–Y 2O 3 coatings were studied using an optical microscope, a scanning electron microscope, and an SRV high-temperature friction and wear tester. The LPHS coatings exhibit distinctly reduced porosity, uniform microstructure, high hardness and highly adhesive bonding, although more microcracks and even vertical macrocracks seem to be caused in the LPHS coatings. The ZrO 2 lamellae in the LPHS coatings before and after 800°C wear test consist mainly of the metastable tetragonal (t′) phase of ZrO 2 together with small amount of c phase. The t′ phase is very stable when it is exposed to the wear test at elevated temperatures up to 800°C for 1 h. The friction and wear of the LPHS coatings shows a strong dependence on temperature, changing from a low to a high wear regime with the increase of temperature. At low temperatures, friction and wear of the LPHS coatings is improved by laser irradiation because of the reduced connected pores and high hardness in contrary to the LPPS coating. However, at elevated temperatures, the friction and wear of the LPHS coatings is not reduced by laser irradiation. At room temperature, mild scratching and plastic deformation of the LPHS coatings are the main failure mechanism. However, surface fatigue, microcrack propagation, and localized spallation featured by intersplat fracture, crumbling and pulling-out of ZrO 2 splats become more dominated at elevated temperatures. 相似文献
16.
Austenitic stainless steels are used in applications demanding general corrosion resistance at room or moderate operating temperatures. However, their use is often limited by the relative softness of these materials and their suceptibility to wear and galling. The present investigation deals with the dry sliding wear behaviour of two P/M austenitic stainless steels (AISI 304L and 316L) and their composites containing two different ceramic particles (Al 2O 3 and Y 2O 3) and two different sintering activators (BN and B 2Cr). Unlubricated pin-on-disc wear tests were carried out. Wear mechanisms were analysed by means of scanning electron microscopy and X-ray diffraction. A plastic deformation and particle detachment wear mechanism was revealed. Plasticity during sliding induced an austenite to martensite transformation. The presence of ceramic particles (Al 2O 3 and Y 2O 3) and sintering activators (B 2Cr, BN) improved significantly the wear resistance (especially the combination Al 2O 3 and B 2Cr). Ceramic particles limited plastic deformation while sintering activators decreased final porosity. 相似文献
17.
The effects of rare earth oxide CeO 2 on the microstructure and wear resistance of thermal sprayed Fe–Ni–Cr alloy coatings were investigated. The powders of Fe–Ni–Cr alloy with the addition of CeO 2 were flame sprayed on to a 1045 carbon steel substrate. The coatings were examined and tested for microstructure feature, compositions, and phase structure. Tribological properties of coatings were tested under reciprocating sliding test. The results were compared with those for coatings of the alloy without CeO 2. The comparison indicated that the addition of rare earth oxide CeO 2 could refine and purify the microstructure of coatings, and increase the microhardness of the coatings. As a result, by CeO 2 addition, the friction coefficient of the coatings was decreased slightly and the wear resistance of the coatings was enhanced significantly. 相似文献
18.
AbstractInvestigations were undertaken to determine the erosion corrosion resistance of nanostructured titanium dioxide coatings in 5 vol.-%–3·5 wt-% NaCl slurry at velocities ranging from 1 to 4 m s –1 in a recirculating loop. Two types of nanopowders, spray dried and densified (AE 9342) and chemically precipitated and spray dried (AE 9303) were used. The results were compared with a conventional TiO 2 coated samples (SM 102). Specimen AE 9342 showed a higher resistance compared to AE 9303. No localised corrosion on the above specimen was observed. The erosion corrosion was caused by etching of intersplat boundaries. The erosion corrosion is dependent on surface topography. A homogeneous distribution of nanoagglomerates of unmelted, partially melted nanoparticles embedded in coatings, a large area of melted zone and porosity less than 1% enhances the erosion corrosion resistance of nanostructured titanium dioxide coatings. 相似文献
19.
AbstractIn this work, Al-20Si-5Fe-2Ni/ZrB 2 composites with 0–20?wt% ZrB 2 were fabricated by spark plasma sintering. The effects of ZrB 2 content on the microstructure, mechanical properties and high-temperature tribological behavior of the composites were investigated. The results indicate that Si, Al 5FeSi, and ZrB 2 particles are uniformly distributed in the aluminum matrix. The density, hardness, and compressive strength increase with increasing ZrB 2 content. The friction coefficient and wear rate are dependent on the ZrB 2 content and test temperature. At a certain temperature, the friction coefficient increases with an increase in ZrB 2 content, whereas the wear rate shows a reverse trend. Due to the improvement in thermal stability and high-temperature softening resistance, the composite shows improved wear resistance and increased transition temperature from mild wear to severe wear. 相似文献
20.
MoS 2–Cr coatings with different Cr contents have been deposited on high speed steel substrates by closed field unbalanced magnetron (CFUBM) sputtering. The tribological properties of the coatings have been tested against different counterbodies under dry conditions using an oscillating friction and wear tester. The coating microstructures, mechanical properties and wear resistance vary according to the Cr metal-content. MoS 2 tribological properties are improved with a Cr metal dopant in the MoS 2 matrix. The optimum Cr content varies with different counterbodies. Showing especially good tribological properties were MoS 2–Cr8% coating sliding against either AISI 1045 steel or AA 6061 aluminum alloy, and MoS 2–Cr5% coating sliding against bronze. Enhanced tribological behavior included low wear depth on coating, low wear width on counterbody, low friction coefficients and long durability. 相似文献
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