共查询到20条相似文献,搜索用时 11 毫秒
1.
Xianhui Wang Shuhua Liang Ping Yang Zikang Fan 《Journal of Materials Engineering and Performance》2010,19(9):1330-1336
Al2O3/Cu composites were prepared by external addition of Al2O3, and the effect of Al2O3 content on microstructure, density, hardness, electrical conductivity and vacuum electrical breakdown properties was studied.
The results show that with increasing Al2O3 addition, the density of Al2O3/Cu composite significantly decreases, the hardness sharply increases and then slowly decreases, but the electrical conductivity
invariably decreases. The vacuum breakdown test shows that with increasing Al2O3 addition, the breakdown strength first sharply increases and then decreases when the Al2O3 content exceeds 1.2 wt.%; the chopping current always exhibits a decreasing trend and the arc life first increases and then
decreases. According to the morphology of arc erosion and analysis, the arc erosion resistance increases and then decreases
sharply. In the range of experiments, the optimal arc erosion resistance of Al2O3/Cu composite can be obtained with the addition of 1.2 wt.% Al2O3. 相似文献
2.
Fabrication and Properties of Plasma-Sprayed Al<Subscript>2</Subscript>O<Subscript>3</Subscript>/ZrO<Subscript>2</Subscript> Composite Coatings 总被引:1,自引:0,他引:1
N. Dejang A. Limpichaipanit A. Watcharapasorn S. Wirojanupatump P. Niranatlumpong S. Jiansirisomboon 《Journal of Thermal Spray Technology》2011,20(6):1259-1268
Al2O3
/xZrO2 (where x = 0, 3, 13, and 20 wt.%) composite coatings were deposited onto mild steel substrates by atmospheric plasma spraying of mixed
α-Al2O3 and nano-sized monoclinic-ZrO2 powders. Microstructural investigation showed that the coatings comprised well-separated Al2O3 and ZrO2 lamellae, pores, and partially molten particles. The coating comprised mainly of metastable γ-Al2O3 and tetragonal-ZrO2 with trace of original α-Al2O3 and monoclinic-ZrO2 phases. The effect of ZrO2 addition on the properties of coatings were investigated in terms of microhardness, fracture toughness, and wear behavior.
It was found that ZrO2 improved the fracture toughness, reduced friction coefficient, and wear rate of the coatings. 相似文献
3.
Metal-insulator-semiconductor (MIS) structures containing Ge nanocrystals embedded in both Al2O3 and ZrO2/Al2O3 are fabricated by an ultra-high vacuum electron-beam evaporation method. Secondary ion mass spectroscopy (SIMS) results indicate
that Ge embedded in Al2O3 diffuses towards the surface of the Al2O3 layer after annealing at 800°C in N2 ambient for 30 min. Ge embedded in ZrO2/Al2O3 is stable, thus inducing less leakage current. Capacitance voltage studies indicate that annealing can effectively passivate
the negatively charged trapping centers. Memory effect of the Ge nanoclusters is verified by hysteresis in the C-V curves
in the Al2O3/Ge+Al2O3/Al2O3 and ZrO2/Ge+Al2O3/Al2O3 samples.
This article is based on a presentation in “The 7th Korea-China Workshop On Advanced Materials” organized by the Korea-China
Advanced Materials Cooperation Center and the China-Korea Advanced Materials Cooperation Center, held at Ramada Plaza Jeju
Hotel, Jeju Island, Korea on August 24–27, 2003. 相似文献
4.
Katarína Ďurišinová Juraj Ďurišin Martin Ďurišin 《Journal of Materials Engineering and Performance》2017,26(3):1057-1061
Dispersion-strengthened Cu-Al2O3 materials have been studied over recent years to find an optimum processing route to obtain a high strength, thermal-stable copper alloy designed for modern applications in electrical engineering. The study analyses the influence of 1 vol.% of alumina content on strengthening the copper matrix. Microstructure of the Cu-Al2O3 composite was studied by x-ray diffraction as well as scanning and transmission electron microscopy. The composite shows a homogeneous, thermal-stable nanostructure up to 900 °C due to dispersed alumina nanoparticles. The particles effectively strengthen crystallite/grain boundaries in processes of powder consolidation and annealing of the compact. In contrast to monolithic Cu, the Cu-1 vol.% Al2O3 exhibits more than double strength and hardness. The nanocrystalline matrix and the low amount of alumina particles result in a yield strength of 288 MPa and a ductility of 15% which is a good combination for practical utilization of the material. 相似文献
5.
Xuemei Song Ziwei Liu Mingguang Kong Yongzhe Wang Liping Huang Xuebin Zheng Yi Zeng 《Journal of Thermal Spray Technology》2016,25(4):770-777
The microstructures of three atmospheric plasma-sprayed (APS) Al2O3-ZrO2 coatings were investigated using x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The differences in the microstructures of the three Al2O3-ZrO2 coatings, including their phase compositions, cracks, pores, grain sizes, and solid solutions, were analyzed in detail. A close relationship was observed between the thermal conductivities of the coatings and the microstructures, and the Al2O3-YSZ coatings with more spherical pores, fewer vertical cracks, and finer grains exhibited the lowest thermal conductivity of 0.91 W/m·K. Compared with YSZ coatings, Al2O3-YSZ coatings can exhibit lower thermal conductivity, which may be attributed to the formation of an amorphous phase, smaller grains, and Al2O3-YSZ solid solution. 相似文献
6.
Al2O3/ZrO2/Al2O3 gate stacks were prepared on ultrathin SOI (Silicon on insulator) substrates by ultrahigh vacuum electron beam evaporation
and post-annealed in N2 at 450°C for 30 min. Three clear nanolaminate layered structure of Al2O3(2.1 nm)/ZrO2(3.5 nm)/Al2O3(2.3 nm) was observed with a high-resolution cross-sectional transmission electron microscope (HR-XTEM). High frequency capacitance
voltage (C-V) characteristics of a fully depleted (FD) SOI MOS capacitor at 1 and 5 MHz were studied. The minority carriers
determine the high frequency C-V properties, which is opposite to the case of bulk MOS capacitors. The series resistance of
the SOI substrate is found to be the determinant factor of the high frequency characteristics of FD SOI MOS capacitors.
This article is based on a presentation in “The 7th Korea-China Workshop on Advanced Materials” organized by the Korea-China
Advanced Materials Cooperation Center and the China-Korea Advanced Materials Cooperation Center, held at Ramada Plaza Jeju
Hotel, Jeju Island, Korea on August 24≈27, 2003. 相似文献
7.
Recently, extensive efforts have been made to develop new thermal barrier coating (TBC) materials which can operate at temperatures
above 1523 K over a long term. In this article, LaTi2Al9O19 (LTA) was synthesized by solid-state reaction at 1773 K, and the mechanical properties of the LTA bulk were evaluated. The
microhardness is about 14 GPa, comparable to that of YSZ bulk, whereas the Young’s modulus is about 44 GPa, lower than the
value of YSZ. However, the fracture toughness of 0.8-1 MPa m1/2 is much lower than that of bulk YSZ. A double-ceramic-layer LTA/YSZ TBC structure was proposed and the TBC sprayed by plasma
spraying. Thermal cycling tests of the TBC specimens were performed at 1373 K with a dwell time of 10 min. The LTA remained
good stability with ZrO2 and Al2O3. However, the single layer LTA TBC was cracked at the LTA/bond coat interface after about 300 cycles, due to its poor thermal
shock resistance, while the YSZ TBC yielded a lifetime of about 1000 cycles. The LTA/YSZ TBC remained intact even after 3000
cycles, exhibiting a promising potential as new TBC materials. 相似文献
8.
P. Babadi S. Sadreddini F. Mohsenifar M. Roshani 《Protection of Metals and Physical Chemistry of Surfaces》2016,52(2):249-253
In this study, the effect of electrophoretic voltage changes on Ni—Al2O3 nano-composite coating via two step process electrophoretic, and electrochemically on 1100 Al substrate on morphology, corrosion and wear behaviour were studied. In the first step of deposition for determining the optimum amount of Teri Ethanol Amin activator in electrophoretic suspension Transmission Electron Microscopy (TEM) was used. The amount of alumina particles, Nickel ions in the coating and morphology were studied by Energy-dispersive X-ray spectroscopy (EDX) and Field-Emission Electron Microscopy (FESEM). Nanoparticles distribute more homogenous in deposit within using 40 V voltage. Corrosion behaviour of coating was investigated by polarization technique in 3.5 wt % NaCl which shows a decrease in corrosion current from 13.7 μA/cm2 to 1.46 μA/cm2 versus bare sample. 相似文献
9.
Rohit Kumar A. K. Chaubey Sivaiah Bathula K. G. Prashanth Ajay Dhar 《Journal of Materials Engineering and Performance》2018,27(3):997-1004
Al2O3-10TiC composites were synthesized by spark plasma sintering (SPS) process. Microstructural and mechanical properties of the composite reveal homogeneous distribution of the fine TiC particles in the matrix. The samples were produced with different sintering temperature, and it shows that the hardness and density gradually increases with increasing sintering temperature. Abrasion wear test result reveals that the composite sintered at 1500 °C shows high abrasion resistance (wt. loss ~ 0.016 g) and the lowest abrasion resistance was observed for the composite sample sintered at 1100 °C (wt. loss ~ 1.459 g). The profilometry surface roughness study shows that sample sintered at 1100 °C shows maximum roughness (Ra = 6.53 µm) compared to the sample sintered at 1500 °C (Ra = 0.66 µm) corroborating the abrasion wear test results. 相似文献
10.
Low-power plasma-sprayed FeCrAl/Al2O3 composite coatings with 1.5 mm thickness have been fabricated for radar absorption applications. The effects of FeCrAl content on the coating properties were studied. The FeCrAl presents in the form of a few thin lamellae and numerous particles, demonstrating relatively even distribution in all the coatings. Results show that the micro-hardness and porosity decrease with the increase in FeCrAl content. With FeCrAl content increasing from 28 to 47 wt.%, the bonding strength of the coatings with 1.5 mm thickness increases from 10.5 to 27 MPa, and the failure modes are composed of cohesive and adhesive failure, which are ascribed to the coating microstructure and the residual stress, respectively. 相似文献
11.
This paper investigates the high-temperature oxidation of cermet coatings composed of two types of nanosized particles (WC and a mixture of WC and Al2O3) incorporated in nickel and produced by co-electrodeposition. For this purpose, high-temperature oxidation tests were conducted at three temperatures (500, 600, and 700 °C) in dry air with 6 time intervals up to 96 h and mass changes at each specific time interval was measured. Statistical techniques were used to calculate the oxidation rate constants (k) and growth-rate time constants (a) for all coatings. The confidence intervals associated with tests were also calculated. The results showed linear to sub-parabolic oxidation rates for coatings composed of only WC particles and sub-liner to liner oxidation rates for coating with both WC and Al2O3 particles. The reduction in oxidation rates for coatings with both WC and Al2O3 particles were correlated to the addition of Al2O3 particles in the matrix. 相似文献
12.
Chengqi Yan Yonghai Kang Lingqian Kong Shengyu Zhu 《Journal of Materials Engineering and Performance》2017,26(1):168-176
The Ni3Al matrix self-lubricating composite was fabricated by powder metallurgy technique. The tribological behavior of the composite sliding against commercial Si3N4, SiC and Al2O3 ceramic balls was investigated from 20 to 1000 °C. It was found that the composite demonstrated excellent lubricating properties with different friction pairs at a wide temperature range, which can be attributed to the synergetic effect of Ag, fluorides, and molybdates formed by oxidations. The Ni3Al matrix self-lubricating composite/Si3N4 couple possessed the stable friction coefficient and wear rate. 相似文献
13.
Xianhui Wang Shuhua Liang Ping Yang Zhikang Fan 《Journal of Materials Engineering and Performance》2010,19(6):906-911
In order to clarify the relationship between the microstructure and the arc erosion behavior of metal-matrix composite, Al2O3/Cu composites with different distributions of Al2O3 particles were prepared by high energy ball milling and powder metallurgy. The effect of milling time on microstructure,
properties, and arc erosion behavior of Al2O3/Cu composite was investigated. The results show that the distribution of Al2O3 particles improves significantly with increase of milling time, but Al2O3 particles will be aggregated if milling time is too long. The optimal milling time is 24 h in the range of experiments. A
uniform distribution of Al2O3 particles in copper matrix can improve the hardness, electrical conductivity, average breakdown strength, chopping level,
and arc life. With improvement in the distribution of Al2O3 particles, the erosion area becomes larger, and the erosion pits become shallower and are dispersed more uniformly. 相似文献
14.
Xiang-Hu Gao Zhi-Ming Guo Qing-Fen Geng Peng-Jun Ma Gang Liu 《Journal of Materials Engineering and Performance》2017,26(1):161-167
Surface-textured Mo thin film is fabricated by magnetron sputtering through the adjustment of deposition parameters, which exhibits a high absorptance of 0.80 and a low emittance of 0.09. The single-layer Mo deposited on stainless steel (SS) is characterized by x-ray diffraction (XRD), ultra-high resolution scanning electron microscope, atomic force microscope and optical measurement. The controlled surface roughness combined with larger aspect ratio contributes much to the high absorptance and low emittance. Based on the SS/Mo coating, a spectrally selective coating (SS/Mo/Al2O3) is designed and fabricated. The coating shows an amorphous structure and exhibits an absorptance of 0.90 and an emittance of 0.08. Tauc-Lorentz and Drude free-electron models are used to modeling the optical properties of Al2O3 and Mo layers by phase-modulated spectroscopic ellipsometry. 相似文献
15.
E. V. Zozulya A. I. Il’inskii I. N. Kolupaev 《The Physics of Metals and Metallography》2011,111(2):155-157
Methods of X-ray diffraction and transmission electron microscopy were used to study the microstructure of dispersion-strengthened
Cu-Al2O3 nanocomposites obtained by the method of simultaneous deposition of Cu and Al2O3 from the vapor phase. The effect of the size of particles of the oxide (Al2O3) and of their content on the electrical resistance of the composite has been considered. The results obtained make it possible
to suppose that the main structural factor that determines the electrical resistance of the composite are nanodispersed particles
of Al2O3 with a size of less than 20 nm. 相似文献
16.
Lutz-Michael Berger Kerstin Sempf Yoo Jung Sohn Robert Vaßen 《Journal of Thermal Spray Technology》2018,27(4):654-666
The formation and decomposition of aluminum titanate (Al2TiO5, tialite) in feedstock powders and coatings of the binary Al2O3-TiO2 system are so far poorly understood. A commercial fused and crushed Al2O3-40%TiO2 powder was selected as the feedstock for the experimental series presented in this paper, as the composition is close to that of Al2TiO5. Part of that powder was heat-treated in air at 1150 and 1500 °C in order to modify the phase composition, while not influencing the particle size distribution and processability. The powders were analyzed by thermal analysis, XRD and FESEM including EDS of metallographically prepared cross sections. Only a maximum content of about 45 wt.% Al2TiO5 was possible to obtain with the heat treatment at 1500 °C due to inhomogeneous distribution of Al and Ti in the original powder. Coatings were prepared by plasma spraying using a TriplexPro-210 (Oerlikon Metco) with Ar-H2 and Ar-He plasma gas mixtures at plasma power levels of 41 and 48 kW. Coatings were studied by XRD, SEM including EDS linescans of metallographically prepared cross sections, and microhardness HV1. With the exception of the powder heat-treated at 1500 °C an Al2TiO5-Ti3O5 (tialite–anosovite) solid solution Al2?xTi1+xO5 instead of Al2TiO5 existed in the initial powder and the coatings. 相似文献
17.
Marzanna Ksiazek Maria Richert Aam Tchorz Lukasz Boron 《Journal of Materials Engineering and Performance》2012,21(5):690-695
There is a growing interest in metal-ceramic bonding for wide range of applications in electronic devices and high technology
industry for fabrication of metal matrix composites and bonding of ceramic components to metals. The object of the work was
to study the effect of Ti, Nb, and Ti + Nb thin films deposited by PVD method on alumina substrates on structure and bond
strength properties of Al/Al2O3 joints. The joints were fabricated using the results of a wetting experiment and the sessile drop method at a temperature
of 1223 K in a vacuum of 0.2 MPa for 30 min of contact. The structure of the metal/ceramic interface was investigated using
scanning electron microscopy. The elemental distribution at the metal-ceramic interface was analyzed using energy dispersive
x-ray spectroscopy. Transmission electron microscopy was also used to investigate some aspects of the metal/ceramic interface.
The bond strength properties of joints were measured using shear test. The shear strength results demonstrated significant
improvement of shear strength of Al/Al2O3 joints due to the application of Ti + Nb thin film on alumina substrate. Microstructural investigations of the interface
indicated that Al/coating/Al2O3 couples have diffusion transition interface which influences the strengthening of these joints. A conclusion could be drawn
that the presence of thin film layers changes the character of interaction and leads to the formation of new reaction products
in the bonding layer. 相似文献
18.
K. A. Habib D. L. Cano C. T. Caudet M. S. Damra I. Cervera J. Bellés P. Ortells 《Journal of Materials Engineering and Performance》2017,26(4):1647-1656
The influence of micrometric alumina (low surface area-to-volume ratio) and nanometric alumina (high surface area-to-volume ratio) on microstructure, hardness and abrasive wear of a NiCrBSi hardfacing alloy coating applied to an AISI 304 substrate using flame spraying (FS) combined with surface flame melting (SFM) is studied. Remelting after spraying improved the mechanical and tribological properties of the coatings. Microstructural characterization using XRD, SEM and EDS indicated that alumina additions produced similar phases (NiSi, Ni3B, CrC and Ni31Si12) regardless of the alumina size, but the phases differed in morphology, size distribution and relative proportions from one coating to another. The addition of 12 wt.% nanometric Al2O3 increased the phases concentration more than five- to sixfold and reduced the hard phases size about four-to threefold compared with NiCrBSi + 12 wt.% micrometric Al2O3. Nanoalumina led to reduced mass loss during abrasive wear compared to micrometric alumina and greater improvement in hardness. 相似文献
19.
Jiang-feng Cheng Gui-rong Li Hong-ming Wang Pei-si Li Chao-qun Li 《Journal of Materials Engineering and Performance》2018,27(3):1083-1092
At T6 state, Al–Zn–Mg–Cu aluminum matrix composites reinforced with Al2O3 particles generated in situ were subjected to high pulsed magnetic fields at different magnetic induction intensities (B = 2, 3 and 4 T). The results show that the dislocation densities in the treated samples increased with increasing B, and the magnetoplastic effect was determined to be the primary cause. The effect of the magnetic field is believed to alter the spin state of free electrons between dislocations and obstacles from the singlet state (associated with high bonding energy) to the triplet state (low bonding energy). The maximum ultimate tensile strength of 532 MPa was obtained at B = 4 T with 30 pulses, which was 20.7% higher than that of the initial sample, primarily because of dislocation strengthening. At B = 2 T, the elongation was at its maximum of 9.3%, representing an increase of 12% compared with the initial sample, while the associated ultimate tensile strength (447 MPa) was still higher than that of the untreated sample (440 MPa). The relationship between mechanical properties and microstructure was analyzed, and the improved properties observed in this work are explained by the transition of the electron spin state and the piling up of dislocations. 相似文献
20.
Agata Strojny-Nędza Katarzyna Pietrzak Witold Węglewski 《Journal of Materials Engineering and Performance》2016,25(8):3173-3184
In order to meet the requirements of an increased efficiency applying to modern devices and in more general terms science and technology, it is necessary to develop new materials. Combining various types of materials (such as metals and ceramics) and developing composite materials seem to be suitable solutions. One of the most interesting materials includes Cu-Al2O3 composite and gradient materials (FGMs). Due to their potential properties, copper-alumina composites could be used in aerospace industry as rocket thrusters and components in aircraft engines. The main challenge posed by copper matrix composites reinforced by aluminum oxide particles is obtaining the uniform structure with no residual porosity (existing within the area of the ceramic phase). In the present paper, Cu-Al2O3 composites (also in a gradient form) with 1, 3, and 5 vol.% of aluminum oxide were fabricated by the hot pressing and spark plasma sintering methods. Two forms of aluminum oxide (αAl2O3 powder and electrocorundum) were used as a reinforcement. Microstructural investigations revealed that near fully dense materials with low porosity and a clear interface between the metal matrix and ceramics were obtained in the case of the SPS method. In this paper, the properties (mechanical, thermal, and tribological) of composite materials were also collected and compared. Technological tests were preceded by finite element method analyses of thermal stresses generated in the gradient structure, and additionally, the role of porosity in the formation process of composite properties was modeled. Based on the said modeling, technological conditions for obtaining FGMs were proposed. 相似文献