共查询到20条相似文献,搜索用时 15 毫秒
1.
Highly efficient organic light-emitting devices (OLEDs) have been realized by insertion of a thin insulating lithium fluoride (LiF) layer between aluminum (Al) cathode and an electron transport layer, tris-(8-hydroxyquinoline) aluminum (Alq(3)). In this paper, we study the surface morphology of LiF on Alq(3) by synchrotron X-ray scattering and atomic force microscopy (AFM) as a function of thickness of LiF. We also study the interdiffusion of LiF into Al cathode as well as into Alq(3) layer as a function of temperature. Initially, LiF molecules are distributed randomly as clusters on the Alq(3) layer and then gradually form a layer as increasing LiF thickness. The interdiffusion of LiF into Al occurs more actively than into Alq(3) in annealing process. LiF on Alq(3) induces the ordering of Al to (111) direction strongly with increasing LiF thickness. 相似文献
2.
We have fabricated vertical-type organic thin-film transistors (OTFTs) using tris-(8-hydroxyquinoline) aluminum (Alq3) as an n-type active material. Vertical-type OTFT using Alq3 has a layered structure of Al(source electrode)/Alq3(active layer)/Al(gate electrode)/Alq3(active layer)/ITO glass(drain electrode). Alq3 thin films containing various surface morphologies could be obtained by the control of evaporation rate and substrate temperature. The effects of the morphological control of Alq3 thin layer on the grain size and the flatness of film surface were investigated. The characteristics of vertical-type OTFT significantly influenced the growth condition of Alq3 layer. 相似文献
3.
《Wear》2007,262(5-6):641-648
The present study concerns the wear behavior of laser composite surfaced Al with SiC and Al + SiC particulates. A thin layer of SiC and Al + SiC (at a ratio of 1:1 and dispersed in alcohol) were pre-deposited (thickness of 100 μm) on an Al substrate and laser irradiated using a high power continuous wave (CW) CO2 laser. Irradiation leads to melting of the Al substrate with a part of the pre-deposited SiC layer, intermixing and followed by rapid solidification to form the composite layer on the surface. Following laser irradiation, a detailed characterization of the composite layer was undertaken in terms of microstructure, composition and phases. Mechanical properties like microhardness and wear resistance were evaluated in detail. The microstructure of the composite layer consists of a dispersion of partially melted SiC particles in grain refined Al matrix. Part of the SiC particles are dissociated into silicon and carbon leading to formation of the Al4C3 phase and free Si redistributed in the Al matrix. The volume fraction of SiC is maximum at the surface and decreases with depth. The microhardness of the surface improves by two to three times as compared to that of the as-received Al. A significant improvement in wear resistance in the composite surfaced Al is observed as compared to the as-received Al. The mechanism of wear for as-received vis-à-vis laser composite surfaced Al has been proposed. 相似文献
4.
The tribological properties of a Fe3Al material in an aqueous solution of 1 mol/l H2SO4 corrosive environment sliding against a Si3N4 ceramic ball are studied using an Optimol SRV oscillating friction and wear tester in a ball-on-disc contact configuration. We investigate the effects of load and sliding speed on tribological properties of the Fe3Al material. The worn surfaces of the Fe3Al material are examined by a scanning electron microscope (SEM) and an X-ray photoelectron spectroscope (XPS). It is found that the Fe3Al material exhibits better wear resistance than 1Cr18Ni9Ti stainless steel in the sulfuric acid corrosive environment. The wear rate of the Fe3Al material is on the order of 10?13 m3/m and increases with increasing load, but does not vary below the sliding speed of 0.08 m/s then dramatically increases with increasing sliding speed. The friction coefficient of the Fe3Al material is in the range of 0.1–0.28, and slightly increases with increasing load, and does not vary with the increase of sliding speed. The Fe3Al material occurs tribochemical reaction with the H2SO4 aqueous solution in the friction process. Wear mechanism of the Fe3Al material is dominated by microploughing and corrosive wear. 相似文献
5.
Wei Shouzheng Li Yajiang Wang Juan Liu Kun Zhang Pengfei 《The International Journal of Advanced Manufacturing Technology》2014,70(5-8):1137-1142
Butt joining of titanium alloy Ti–2Al–Mn to aluminum 1060 using AlSi5 filler wire was conducted using pulsed gas metal arc welding. Joining mechanism of Ti–2Al–Mn/Al 1060 dissimilar joint with different welding heat input was investigated. Formations of precipitation and Ti/Al interface were discussed in detail. Fusion zone near aluminum is composed of α-Al dendrites and Al–Si hypoeutectic structures. A few TiAl3 precipitations appear in the weld metal owing to metallurgical reactions of Al with dissolved Ti. When the welding heat input was in the range of 1.87–2.10 kJ/cm, titanium alloy Ti–2Al–Mn and Al 1060 were joined together by the formation of a complex Ti/Al interface. With a low welding heat input, a serrate TiAl3 interfacial reaction layer was formed near Ti/Al interface. With the increasing of the welding heat input, α-Ti, Ti7Al5Si12, and TiAl3 layers were formed orderly from Ti–2Al–Mn to weld metal. 相似文献
6.
《Wear》2006,260(4-5):486-492
In order to improve the wear resistance of an aluminum alloy, an in situ synthesized TiB2 particulate-reinforced metal matrix composite coating was formed on a 2024 aluminum alloy by laser cladding with a powder mixture of Fe-coated boron, Ti and Al was successfully achieved using a 3-kW CW CO2 laser. The chemical composition, microstructure and phase structure of the composite clad coating were analyzed by energy dispersive X-ray spectroscopy (EDX), SEM, TEM and XRD. The nanohardness and the elastic modulus of the phases of the coating have been examined. The dry sliding wear behaviour of the coating was investigated using a pin-on-ring machine under four loads, namely 8.9, 17.8, 26.7, and 35.6 N. It has been found that the wear characteristics of cladding were completely dependent on the content and morphology of the TiB2 particulate and intermetallic in the microstructure and the applied load. At the lowest load (8.9 N), with increasing content of TiB2 particulate and intermetallic, the wear weight loss of the laser cladding was decreased. At higher loads (17.8, 26.7, and 35.5 N), the 2024 Al alloy exhibited superior wear resistance to the particle-reinforced metal matrix composite cladding. 相似文献
7.
P. Iglesias M.D. Bermúdez F.J. Carrin S. Chandrasekar W.D. Compton 《Tribology International》2007,40(3):479-489
The tribological behavior of bakelite resin–matrix composites reinforced with nanocrystalline Al 6061 T6 particles produced by machining (grain size 70–500 nm) has been studied using block-on-ring and pin-on-disk tests. The polymer–matrix composite reinforced with nanostructured Al 6061 particles aged for 10 h [Al 6061 (3) 10 h] shows a wear reduction of around 60% with respect to the conventional microstructured reinforcement. Also it shows the lowest wear rates when compared with the nanostructured reinforcements aged for 5 h or 1 h, respectively. Friction coefficients and wear rates increased with increasing sliding speed and normal load. Under 10 N and 0.10 m s−1, Al 6061 (3) 10 h showed an initial friction and contact temperature increase and a very severe wear with material transfer to the steel ball surface. Increasing the steel–composite contact temperature to 100 °C (1 N; 0.05 m s−1) produced a one order of magnitude decrease both in friction and wear. Wear mechanisms for the polymer matrix and the aluminum reinforcement are discussed on the basis of SEM and EDS observations. 相似文献
8.
《Wear》2007,262(7-8):826-832
The non-lubricated, sliding friction and wear behavior of Ti3Si(Al)C2 and SiC-reinforced Ti3Si(Al)C2 composites against AISI 52100 bearing steel ball were investigated using a ball-on-flat, reciprocating tribometer at room temperature. The contact load was varied from 5 to 20 N. For monolithic Ti3Si(Al)C2, high friction coefficients between 0.61 and 0.90 and wear rates between 1.79 × 10−3 and 2.68 × 10−3 mm3 (N m)−1 were measured. With increasing SiC content in the composites, both the friction coefficients and the wear rates were significantly decreased. The friction coefficients reduced to a value between 0.38 and 0.50, and the wear rates to between 2.64 × 10−4 and 1.93 × 10−5 mm3 (N m)−1 when the SiC content ranged from 10 to 30 vol.%. The enhanced wear resistance of Ti3Si(Al)C2 is mainly attributed to the facts that the hard SiC particles inhibit the plastic deformation and fracture of the soft matrix, the oxide debris lubricate the counterpair, and the wear mode converts from adhesive wear to abrasive wear during dry sliding. 相似文献
9.
This study aims to identify the optimal burnout temperature (BT) of a plaster mold that was used in bimetal composite production. To achieve this goal, the mold was gradually heated up to 600, 650, 700, and 750?°C prior to melt infiltration casting. Molten A356 aluminum alloy was cast into mold at 730?°C for each casting process. Fifty percent porous 304 stainless steel (SS) preforms, obtained by assembling recycled SS shavings, were placed in a mold and infiltrated by A356 alloy until solidification was completed. The produced bimetal composites were subjected to a ball-on-disc tribometer with loads of 5, 10, and 15 N for 100 m sliding distance using an Al2O3 ball as a counterpart. θ-Fe4Al13 and η-Fe2Al5 phases were formed at A356 Al–304 SS interfaces for all samples. Wear rates increased with increasing load and decreased with increasing BT, except at 750?°C. At this temperature, interfacial phases with excessively increased layer thickness, hardness, and brittleness were fragmentized during the test, and these cracked particles decreased wear resistance by participating in the wear process. The most suitable BT of the mold was found to be 700?°C, considering the microstructure and wear results of bimetal composites. 相似文献
10.
V. S. Terent’ev V. A. Simonov 《Optoelectronics, Instrumentation and Data Processing》2015,51(6):609-616
An experimental method of fabrication of a sensor based on a metal–dielectric structure (Al + ZnS) and optimization of its characteristics is described. The coefficient of light reflection (p-polarization) from the aluminum layer is studied as a function of the layer thickness for different angles of incidence at the wavelength of 532 nm. Based on calculations, which are qualitatively consistent with experimental results, a structure consisting of matched layers of aluminum and zinc sulfide is fabricated; this structure has a higher angular resolution than the aluminum film with no dielectric coating. The detection limit of angular measurements by the sensor based on this structure is estimated as 2.6 · 10-5 RIU (refraction index units). 相似文献
11.
《Wear》2006,260(4-5):450-457
Intermetallic Mo(Si,Al)2, Mo(Si,Al)2/Al2O3, Mo(Si,Al)2/SiC and Mo(Si,Al)2/ZrO2 composites produced by spark plasma sintering of mechanically alloyed powders were tested on a block-on-cylinder apparatus, sliding against an AA6063 alloy cylinder at elevated temperature. Abrasion, micro-fracture and surface tribochemical reactions were found to be the operative wear mechanisms, producing severe wear in the investigated alloys. Abrasive wear by pull-out of Al2O3 and micro-fracture of Mo(Si,Al)2 particles promotes severe wear in the Mo(Si,Al)2/Al2O3 composite. In the Mo(Si,Al)2/SiC composites, hard SiC inclusions suppressed the abrasive wear, but a tribochemical reaction was found to be the dominant wear mechanism. A combination of abrasion by pull-out of Al2O3 particles and a tribochemical reaction was revealed to be the main wear mechanism in the Mo(Si,Al)2/ZrO2 materials. The brittleness index B = H/K1C was applicable for prediction of the relative wear resistance. In agreement with the suggested model, the lowest wear rate, corresponding to B = 5.5–6.5 μm−1/2, was found in the Mo(Si,Al)2/30 vol.% SiC and Mo(Si,Al)2/30 vol.% ZrO2 composites. 相似文献
12.
Hsin-Jen Chen Kun-Ling Wu Biing-Hwa Yan 《The International Journal of Advanced Manufacturing Technology》2014,72(1-4):319-332
Electrical discharge coating (EDC) performs not only machining but also surface modification of workpiece by changing the polarity of the electrode and dielectric medium. As a candidate of metal bipolar plate in proton exchange membrane fuel cell application, machined Al alloy needs surface coating to overcome its poor corrosion resistance. The goal of this study was to investigate the coating characteristics of 6061-T6 aluminum (Al) alloy machined using titanium (Ti)-sintered electrodes in wet and dry EDC. The results show that in wet EDC using cathodic T-8 sintered electrode, both material removal rate (MRR) and tool wear rate (TWR) were kept reasonably low. Discharge current (I p) and pulse duration (T on) are the main determinants of the morphology of the EDCed Al alloy surface. The appropriate parameters for wet EDC are found to be 1 A?<?I p?<?8 A and 9 μs?<?T on?<?100 μs at DF?=?27 %. Adding TiN powder to kerosene not only improved the EDCed surface quality but also decreased the coefficient of friction. The formation of a TiC layer on the machined surface prolonged the onset of friction transition, which would in turn enhance the wear resistance of the machined surface. However, no TiN layer was formed during wet EDC. On the other hand, in dry EDC using anodic T-6 and T-8 sintered electrodes, both MRR and TWR were below zero. A pure TiN layer of 20-μm thickness was deposited on the EDCed surface and featured good spallation resistance. The appropriate dry EDC parameters for forming a pure TiN layer on a workpiece surface are found to be 1 A?<?I p?<?30 A and 6 μs?<?T on?<?72 μs at DF?=?16 %. From the experimental results of this study, the application of EDC to surface modification during fabrication of the fluid pattern on an Al metal bipolar plate can be expected. 相似文献
13.
Influence of coating thickness on rolling contact fatigue of alumina ceramics thermally sprayed on steel roller 总被引:4,自引:2,他引:2
Masahiro Fujii Jiabin Ma Akira Yoshida Sadato Shigemura Kazumi Tani 《Tribology International》2006,39(11):1447-1453
The influence of the sprayed layer thickness on rolling contact fatigue of a thermally sprayed alumina ceramics with a nominal composition of Al2O3–2.3 mass% TiO2 was investigated using a two-roller test machine under pure rolling contact condition with oil lubricant. The influence of undercoating of sprayed nickel-based alloy on rolling contact fatigue was also investigated. Thicknesses of the ceramics-sprayed layer of tested rollers were 0.2, 0.5 and 1.0 mm. The failure mode of sprayed rollers was spalling caused by subsurface cracking. In the case of sprayed rollers without undercoating, rolling contact fatigue strength of rollers with 0.2 mm thickness sprayed layer was the smallest. Rolling contact fatigue strength of sprayed roller with 0.2 mm thickness sprayed layer was improved by undercoating. In case the failure depth was small as compared with the thickness of sprayed layer, effect of undercoating on the rolling contact fatigue strength was little. The depths where the maximum values of subsurface shear stresses occurred, almost corresponded to the observed depth of spalling cracks. 相似文献
14.
A sapphire convex surface was loaded against a reciprocating flat SiC counterface material. In this particular study the chemical nature of the wear surfaces and associated features such as the wear debris and local areas of material transfer have been studied using analytical techniques such as EDX, XPS and AES. Prior to wear tests the SiC substrate is covered with a thin (1–2 nm) layer of SiO2. During wear the thickness of this layer is substantially reduced, and wear debris of a cylindrical morphology is produced. Examination of the outer 1–2 μm of the wear debris, as well as the first few atomic layers, by EDX and AES, respectively, showed very similar results in areas rich in oxygen accompanied by varying quantities of Al and Si but litte carbon. It is proposed that the wear debris is initially produced by the fragmentation of asperities on the two wear surfaces followed by the transfer of a wear film of SiO2. Such equiaxed debris is then agglomerated into a characteristic cylindrical particle that lies normal to the reciprocating motion. 相似文献
15.
In this study, AISI 8620 steel was boronized using the solid state boronizing technique. Processes were carried out at the temperatures of 850, 900 and 950 °C for 2, 4 and 6 h of treatment. Abrasive wear behavior of the samples boronized at different temperatures and treatment durations have been examined. Using boronized and unboronized samples, abrasive tests were conducted using pin on disc test apparatus. 80 and 120 mesh aluminum oxide (Al2O3) abrasive papers were used in the abrasion experiments and the samples were subjected to abrasion under 10, 20 and 30 N loads. Boronized steels exhibited an improvement in abrasive wear resistance reaching up to 500%. Microstructures and wear surfaces of the samples were inspected using SEM microscopy. SEM examinations revealed that the thickness of the boride layer on the steel surfaces changes with changing process durations and temperatures. The presence of boride formed in the borided layer at the surface of the steels were determined by XRD analysis and microhardness values of the iron borides (FeB, Fe2B) formed on the steel surface were found to be over 1600 HV. 相似文献
16.
Al/Cu/Al and Cu/Al/Cu triple layers with approximately 10 nm single layer thickness deposited on tungsten substrates were analyzed in the early stages of reactive interdiffusion by means of atom probe tomography. The first reaction product is found after 5 min thermal treatment at 110 degrees C and identified by direct chemical analysis to be Al2Cu. Surprisingly, we found a significant asymmetry in the reaction rate of the new phase with the stacking sequence: the thickness of the product grown at the interfaces, at which Cu is deposited on top of the Al layer, is approximately 1.5-2 times thicker than the other one at the interfaces at which Al is deposited onto a Cu layer. On the other hand, at both interfaces the thickness of the product layer depends parabolically on time. No precursory interdiffusion and no distinct nucleation process of the product are observed. 相似文献
17.
The production of Ni3Al was performed under an uniaxial pressure of 150 MPa at 1050 °C for 1 h. The formation temperature of Ni3Al was determined to be 655 °C. The presence of Ni3Al was confirmed by XRD analysis. SEM analysis revealed that the Ni3Al phase has very low porosity. The relative density and microhardness of test materials were 97.8% and about 359±31 HV1.0, respectively. The specific wear rate of Ni3Al was 0.029 mm3/N m for 2 N, 0.017 mm3/N m for 5 N and 0.011 mm3/N m for 10 N, respectively. The distribution of alloying elements was determined by energy-dispersive spectroscopy (EDS). 相似文献
18.
The Ni3Al matrix composites with addition of 10, 15, and 20 wt% BaMoO4 were fabricated by powder metallurgy technique, and the tribological behaviors were studied from room temperature to 800 °C.
It was found that BaAl2O4 formed during the fabrication process. The Ni3Al composites showed poor tribological property below 400 °C, with high friction coefficients (above 0.6) and wear rates (above
10−4 mm3/Nm). However, the composites exhibited excellent self-lubricating and anti-wear properties at higher temperatures, and the
composite with addition of 15 wt% BaMoO4 had the lowest wear rate (1.10 × 10−5 mm3/Nm) and friction coefficient (0.26). In addition, the results also indicated that BaAl2O4 for the Ni3Al composites did not exhibit lubricating property from room temperature to 800 °C. 相似文献
19.
The accuracy of nanopositioning is to a large extent limited by the friction-caused errors, particularly in vacuum environments. An investigation of the friction behaviour of sp2-bonds dominating diamond like carbon (DLC) coatings and WC1−x/DLC, WC(N)/DLC multilayer coatings, which are considered to be used in nanopositioning in vacuum, have been performed by a vacuum microtribometer. By using an atomically smooth Si sphere as a counterface, the reciprocating sliding friction was measured at a normal load <5 mN, and running speed at a 1–100 μm/s in ambient air and in ultra high vacuum (UHV) at 10−7 Pa, and correlated with microstructures and properties of the coatings. When tested in UHV, the coefficient of friction (COF) for pure DLC coatings (thickness: 700 nm) changes significantly between 0.2 and 0.4. Once the thickness of DLC layers is limited to 5 nm by formation of multilayer coatings, the COF in UHV decreases by nearly one order to 0.02–0.05. We suggest that the deformation of DLC films and the transfer films determines COF. Thick DLC coatings can induce more plastic deformation and consumes more energy in sliding resulting in a high COF. Thickening of the transfer film in running leads to a continuous decrease of COF since the deformation of the transfer films turns easier. The low COF of multilayer coatings is mainly due to their confinement of the thickness of DLC films. A consistent velocity-strengthening frictional behaviour of both WC1−x/DLC and WC(N)/DLC coatings in UHV indicates that the transfer films acting as a thin layer of granular material. Further study of the friction behaviour with the presence of such granular materials might be interesting for the further development of tribological coatings for vacuum applications. 相似文献
20.
Paul M. Jones Alexei Merzikline Xiaoping Yan Lei Li Lang Dinh Michael Stirniman Huan Tang 《Tribology Letters》2011,44(2):201-211
Magnetic hard disks coated with ztetraol lubricant were characterized with temperature programed desorption (TPD) and X-ray
photoelectron spectroscopy (XPS). Ztetraol was found to have two adsorbed states, with desorption temperatures of ~650 and ~950 K.
The complete removal of the low temperature state by solvent extraction identified it as due to the mobile lubricant. Desorption
of the CF3 mass fragment was observed only at high temperature, indicating that lubricant in this state was in contact with the surface,
which allowed the assignment of this high temperature state to the bonded lubricant. UV irradiation was found not to alter
the TPD of the unextracted lubricant film. In contrast, the TPD of the UV-bonded layer remaining after extraction was observed
to have only one desorption state, stabilized at ~40 K higher temperature as compared with the naturally bonded layer. XPS
of the mobile layer was accomplished using spectral subtraction of the C1s carbon overcoat peak (284.8 eV BE), and the perfluoroethylene
and perfluoromethylene lubricant peaks (293.5 and 295.0 eV BE, respectively), as a function of UV exposure. No change in the
mobile lubricant layer was found with increasing UV exposure. C1s XPS of the UV-bonded layer identified five surface species
and assigned XPS peaks to each: the carbon overcoat peak at 284.8 eV BE, ether peak at 286.4 eV BE, organic acid peak at 288.7 eV
BE, perfluoroethylene peak at 293.5 eV BE, and the perfluoromethylene peak at 295.0 eV BE. Changes in the relative intensity
of the assigned peaks with increasing UV irradiation exposure time were observed. The integration of the assigned XPS peaks
from the UV-bonded layer with increasing UV exposure was used to identify UV dependent changes in the bonded layer. A significant
relative decrease in the perfluoromethylene lubricant component was observed with increasing exposure, with a simultaneous
increase of both the ether and organic acid surface concentrations. Quantum chemical calculations using small molecular models
of the ztetraol were used to elucidate the XPS and TPD observations. The calculations revealed that the lubricant is fragmented
with irradiation, forming reactive end groups, a volatile CF2O, and a hydrolyzeable CFO terminated fragment all consistent with the XPS results. The mechanistic implications and the possible
surface chemistry are discussed. 相似文献