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1.
Investigation of tribological and mechanical properties Al2O3–SiC reinforced Al composites manufactured by casting or P/M method 总被引:1,自引:0,他引:1
Bekir Sadk Ünlü 《Materials & Design》2008,29(10):2002-2008
In this study, Al based Al2O3 and SiC particle reinforced composite materials were manufactured by casting or P/M method. Tribological properties of these composite materials were investigated by wearing with 10 N load and 50 rpm on a pin-on-disc wear test rig at dry conditions. Mechanical properties were investigated. The effects of reinforce materials on tribological and mechanical properties were investigated. In addition to that microstructure of these materials were investigated by optical and SEM microscope. Tribological and hardness properties of composites significantly improved by the use of particle reinforced into Al. 相似文献
2.
Porous unidirectional Si2N2O-Si3N4 composite was fabricated by in-situ nitriding of a porous unidirectional Si substrate. The porous unidirectional Si substrate having a diameter of 450 μm, was prepared by forming ethanol bubbles in a slurry which contained Si, Y2O3, Al2O3 and methylcellulose powder. After nitridation at 1400 °C, the Si substrate was transformed into Si2N2O-Si3N4 composite and the pore surface of the unidirectional Si2N2O-Si3N4 composite was covered throughout with Si2N2O fibers, which had a diameter of about 55 nm. The Si2N2O fibers were orthorhombic single-crystals with an amorphous layer having a thickness of about 1 nm. The compressive strength of the in-situ synthesized Si2N2O-Si3N4 composite was about 30 MPa. 相似文献
3.
《材料与设计》2015
In this paper, the influence of the addition of Al2O3 particles on the microstructure and wear properties of Fe-based amorphous coatings prepared by high velocity oxygen fuel (HVOF) has been studied. The wear behaviors of the composite coatings were evaluated against Si3N4 in a pin-on-disk mode in air and in 3.5 wt.% NaCl solution. It was found that the Al2O3 particles were homogenously distributed in the amorphous matrix and the composite coatings exhibited improved wear resistance and reduced coefficient of friction (COF) in both air and wet conditions as compared to the monolithic amorphous coating. The composite coating reinforced with 20 wt.% Al2O3 particles exhibit the best wear performance, which, for example, has extremely low COF (< 0.2) and high wear resistance (2–3 times higher than monolithic amorphous coating). Detailed analysis on the worn surface indicated that the wear mechanism for the amorphous and composite coatings is similar and is dominated by oxidative delamination in air and by corrosion wear in 3.5% NaCl solution. The enhanced wear resistance is mainly attributed to the addition of Al2O3 particles which exhibit high hardness, good corrosion resistance and excellent chemical and thermal stability. 相似文献
4.
Mei-Hui Tsai Hong-Yi WangHsu-Tung Lu I-Hsiang TsengHung-Hua Lu Shih-Liang HuangJui-Ming Yeh 《Thin solid films》2011,519(15):4969-4973
Polyimide (PI) nanocomposites with different proportions of Al2O3 were prepared via two-step reaction. Silicon nitride (Si3N4) was deposited on PI composite films by a RF magnetron sputtering system and used as a gas barrier to investigate the water vapor transmission rate (WVTR). The thermal stability and mechanical properties of a pure PI film can be improved obviously by adding adequate content of Al2O3. At lower sputtering pressure (4 mTorr), the PI/Al2O3 hybrid film deposited with Si3N4 barrier film exhibits denser structure and lower root mean square (RMS) surface roughness (0.494 nm) as well as performs better in preventing the transmission of water vapor. The lowest WVTR value was obtained from the sample, 4 wt.%Al2O3-PI hybrid film deposited with Si3N4 barrier film with the thickness of 100 nm, before and after bending test. The interface bonding, Al-N and Al-O-Si, was confirmed with the XPS composition-depth profile. 相似文献
5.
《Composites Part A》1999,30(4):425-427
Ceramic nanocomposites, Si3N4 matrix reinforced with nano-sized SiC particles, were fabricated by hot pressing the mixture of Si3N4 and SiC fine powders with different sintering additives. Distinguishable increase in fracture strength at low and high temperatures was obtained by adding nano-sized SiC particles in Si3N4 with Al2O3 and/or Y2O3. Si3N4/SiC nanocomposite added with Al2O3 and Y2O3 demonstrated the maximum strength of 1.9 GPa with average strength of 1.7 GPa. Fracture strength of room temperature was retained up to 1400 as 1 GPa in the sample with addition of 30 nm SiC and 4 wt% Y2O3. Striking observation in this nanocomposite is that SiC particles at grain boundary are directly bonded to Si3N4 grain without glassy phases. Thus, significant improvement in high temperature strength in this nanocomposite can be attributed to inhibition of grain boundary sliding and cavity formation primarily by intergranular SiC particles, besides crystallization of grain boundary phase. 相似文献
6.
Effect of cutting speed on the performance of Al2O3 based ceramic tools in turning nodular cast iron 总被引:1,自引:0,他引:1
N. Camucu 《Materials & Design》2006,27(10):997-1006
This paper presents the results of an experimental investigation on the effect of cutting speed in turning nodular cast iron with alumina (Al2O3) based ceramic tools. Three different alumina based ceramic cutting tools were used, namely TiN coated Al2O3 + TiCN mixed ceramic, SiC whisker reinforced Al2O3 and uncoated Al2O3 + TiCN mixed ceramic tool. Turning experiments were carried out at four different cutting speeds, which were 300, 450, 600 and 750 m/min. Depth of cut and feed rate were kept constant at 1 mm and 0.1 mm/rev, respectively, throughout the experiments. Tool performance was evaluated with respect to tool wear, surface finish produced and cutting forces generated during turning. Uncoated Al2O3 + TiCN mixed ceramic was the worst performing tool with respect to tool wear and was the best with respect to surface finish. SiC whisker reinforced Al2O3 exhibited the worst performance with respect to cutting forces. If tool wear, surface finish and cutting force results are considered together, among the three tools studied, TiN coated Al2O3 + TiCN mixed ceramic tool is the most suitable one for turning nodular cast iron, especially at high cutting speeds (Vc > 600 m/min). 相似文献
7.
8.
Bulk Al2O3 dispersed ultrafine-grained (UFG) Cu matrix composite has been fabricated by self-propagating high-temperature synthesis (SHS) casting route. The microstructures and mechanical properties of the as-fabricated materials have been investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis, and microhardness measurements and compression tests, respectively. The results show that the as-fabricated material has small amount of entrapped Al2O3 particles in uniform microstructure Cu having a grain size ranging from 200-500 nm with an elevated compressive yield stress (298 MPa) and an improved microhardness value (1.06 GPa). The possible strengthening mechanism of the product has been discussed. 相似文献
9.
Ni-Co/Al2O3 composite coatings were obtained by pulse reversal electrodeposit (PRC) and direct current electrodeposit (DC). The microstructure of the coatings was characterized by means of SEM, XRD and TEM. Hardness, wear resistance and macro residual stress of coatings were also investigated. The results showed that the microstructure and performance of the coatings were significantly affected by the electrodeposit methods and the Al2O3 particles content. The PRC composite coatings exhibited compact surface, high hardness and excellent wear resistance. The macro residual stress of PRC composite coatings was lower than that of DC ones. With the increasing of Al2O3 particles content, the hardness and wear resistance of the composite coatings increased. 相似文献
10.
M. RaaftT.S. Mahmoud H.M. ZakariaT.A. Khalifa 《Materials Science and Engineering: A》2011,528(18):5741-5746
In the present investigation, A390/graphite and A390/Al2O3 surface composite (SC) layers were fabricated using friction stir processing (FSP). The effect of tool rotational and traverse speeds on the microstructural, mechanical and wear characteristics of the surface layers was studied. The results revealed that increasing the tool rotational speed increases the hardness of the composite layers. The traverse speed has less significant influence on the hardness of the composite layer than the tool rotational speed. The A390/Al2O3 surface composites exhibited higher hardness than the A390/graphite surface composites. The surface composites exhibited better wear resistance than the matrix alloy. The A390/Al2O3 surface composites exhibited lower wear rates than the A390/graphite surface composites. Increasing the tool rotational reduces the wear rate of both A390/Al2O3 and A390/graphite surface composites. 相似文献
11.
Cu–Si3N4 composite coatings were prepared by electrolysis from a copper sulphate solution containing dispersed Si3N4 particles of 0.4 or 1 μm mean size. Wear behavior of Cu–Si3N4 composite and pure copper coatings were evaluated using a pin-on-disc test machine under dry condition sliding. Effects of current density and particle concentration on the incorporation percentage of Si3N4, the preferred orientation of copper crystallites, the microstructure, the microhardness and the wear resistance of the coatings were determined. Si3N4 particles in the copper matrix resulted in the production of composite deposits with smaller grain sizes and led to change the preferred orientation growth from [1 0 0] to [1 1 0]. It was proved that the presence of Si3N4 particles decreases the wear loss and the friction coefficient of the coating. According to the results, the friction coefficient decreased dramatically from 0.52 to 0.26 for pure copper coatings to 0.16–0.24 for Cu–Si3N4 composite coatings. In addition, fluctuation of friction coefficient values for Cu–Si3N4 composite coating was lower compared with the pure copper coating. The wear properties of Cu–Si3N4 composite coatings were shown to depend on the weight fraction, the size and the distribution of co-deposited particles. 相似文献
12.
The present investigation deals with the effect of Al2O3 particle reinforcement on the lubricated sliding behavior of ZA-27 alloy. The composites with 3, 5, and 10 wt% of Al2O3 particles were produced by the compocasting procedure. Tribological properties of alloy and composites were studied, using
block-on-disk tribometer at different specific loads and sliding speeds. The test results revealed that composite specimens
exhibited significantly lower wear rate, but higher coefficient of friction than the matrix alloy specimens in all the combinations
of applied loads and sliding speeds. The improved antiwear characteristics of the composites were influenced by positive effects
of higher frictional heating on compatibility of the composite phases and suppressing micro-cracking tendency. Due to that,
effects of reinforcing hard particles were manifested through the reduced wear rate of composites, especially in conditions
of higher load, lower sliding speeds and higher Al2O3 particle content. In present wear tests, the significant forming of mechanically mixed layers was not noticed, what is confirmed
by the SEM microphotographs. 相似文献
13.
In the present study, the wear behavior of in situ formed Al2O3 reinforced hypereutectic Al–18Si matrix composite coatings have been investigated. These coatings were successfully fabricated with mechanically alloyed Al–12Si and SiO2 powder deposited on aluminum substrates by atmospheric plasma spraying (APS). The produced samples were characterized by means of microscopic examinations, hardness measurements and wear tests. The obtained results pointed out that the amount of in situ formed Al2O3 particles increased with increasing spray distance and decreasing in-flight particle velocity and temperature, which was accompanied by an improvement in hardness and wear resistance. 相似文献
14.
Large-scale ear-like Si3N4 dendrites were prepared by the reaction of SiO2/Fe composites and Si powders in N2 atmosphere. The product was characterized by field emission scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. The results reveal that the product mainly consists of ear-like Si3N4 dendrites with crystal structures, which have a length of several microns and a diameter of 100-200 nm. Nanosized ladder-like Si3N4 was also obtained when changing the Fe content in the SiO2/Fe composites. The Si3N4 nanoladders have a length of hundreds nanometers to several microns and a width of 100-300 nm. The ear-like Si3N4 dendrites are formed from a two-step growth process, the formation of inner stem structures followed by the epitaxial growth of secondary branches. 相似文献
15.
An experimental study has been carried out to investigate the bearing strength behavior of pinned joints of glass fiber reinforced composite filled with different proportions of Al2O3 particles, as a function of filler loading and joint geometry. The weight fractions of the filler in the matrix were 7.5, 10, and 15%. Single-hole pin-loaded specimens of each composite material were tested in tension. The results show that the bearing strength of glass fiber reinforced epoxy composites pinned joints is associated with the filler content and geometric parameters. The increase of the Al2O3 particle loading in the matrix improved the bearing strength of the composites. The highest bearing strengths were obtained for composite specimens with 10 wt.% Al2O3 particle content. Further increases in the Al2O3 particle content in the matrix resulted in a decrease of the bearing strength, but remains above that of the unfilled glass reinforced epoxy composites. 相似文献
16.
A. Shafiei-Zarghani S.F. Kashani-Bozorg A. Zarei-Hanzaki 《Materials Science and Engineering: A》2009,500(1-2):84-91
In this study, a new processing technique, friction stir processing (FSP) was attempted to incorporate nano-sized Al2O3 into 6082 aluminum alloy to form particulate composite surface layer. Samples were subjected to various numbers of FSP passes from one to four, with and without Al2O3 powder. Microstructural observations were carried out by employing optical and scanning electron microscopy (SEM) of the cross sections both parallel and perpendicular to the tool traverse direction. Mechanical properties include microhardness and wear resistance, were evaluated in detail. The results show that the increasing in number of FSP passes causes a more uniform in distribution of nano-sized alumina particles. The microhardness of the surface improves by three times as compared to that of the as-received Al alloy. A significant improvement in wear resistance in the nano-composite surfaced Al is observed as compared to the as-received Al. 相似文献
17.
It is difficult to deposit dense intermetallic compound coatings by cold spraying directly using compound feedstock powders due to their intrinsic low temperature brittleness. A method to prepare intermetallic compound coatings in-situ employing cold spraying was developed using a metastable alloy powder assisted with post heat treatment. In this study, a nanostructured Fe(Al)/Al2O3 composite alloy coating was prepared by cold spraying of ball-milled powder. The cold-sprayed Fe(Al)/Al2O3 composite alloy coating was evolved in-situ to FeAl/Al2O3 intermetallic composite coating through a post heat treatment. The effect of heat treatment on the phase formation, microstructure and microhardness of cold-sprayed Fe(Al)/Al2O3 composite coating was investigated. The results showed that annealing at a temperature of 600 °C results in the complete transformation of the Fe(Al) solid solution to a FeAl intermetallic compound. Annealing temperature significantly influenced the microstructure and microhardness of the cold-sprayed FeAl/Al2O3 coating. On raising the temperature to over 950 °C, diffusion occurred not only in the coating but also at the interface between the coating and substrate. The microhardness of the FeAl/Al2O3 coating was maintained at about 600HV0.1 at an annealing temperature below 500 °C, and gradually decreased to 400HV0.1 at 1100 °C. 相似文献
18.
Synthesis of Si3N4 whiskers in porous SiC bodies 总被引:1,自引:0,他引:1
Si3N4 whiskers were synthesized by the carbothermal reduction process in porous SiC bodies. The SiC bodies had a sponge microstructure with pore sizes of approximately 600 μm. The raw materials for the Si3N4 whiskers were powder mixtures of Si3N4, SiO2 and Si for silicon and phenolic resin for carbon. Cobalt was used as a metal catalyst. The carbothermal reaction was performed at 1400 °C or 1500 °C for 1 or 2 h. The α-Si3N4 whiskers grew inside the SiC pores by the VLS process, and their diameters ranged from 0.1 to 1.0 μm. The length of the grown Si3N4 whiskers was over 100 μm and their growth direction was [100]. 相似文献
19.
Nanoindentation tests were carried out to investigate certain elastic properties of Al2O3/SiCp composites at microscopic scales (nm up to μm) and under ultra-low loads from 3 mN to 250 mN, with special attention paid to effects caused by SiC particles and pores. The measured Young’s modulus depends on the volume fraction of SiC particles and on the composite porosity and it can compare with that of alumina. The Young’s modulus exhibits large scatters at small penetrations, but it tends to be constant with lesser dispersion as the indentation depth increases. Further analysis indicated that the scatter results from specific microstructural heterogeneities. The measured Young’s moduli are in agreement with predictions, provided the actual role of the microstructure is taken into account. 相似文献
20.
Xiaolei ShiYali Dong Fumin Xu Yi TanLai Wang Jenn-ming Yang 《Materials Science and Engineering: A》2011,528(6):2246-2249
The processing and mechanical behaviors of Al2O3-xwt.%SiC (x = 1, 2, 5, ASx) nano-composites prepared by the in situ synthesis of SiC from polycarbosilane (PCS) were investigated. The composites were densified by hot pressing. The microstructure and mechanical properties of the sintered composites were analyzed. The results showed that a fully dense structure was obtained when a few nano-SiC were doped and that the fracture toughness and strength were highly improved compared with those of monolithic Al2O3. The fracture toughness reached 5.1 MPa m1/2 in AS2 composite. The maximum flexural strength was 516 MPa obtained in AS1 composite. 相似文献