- Microstructure and microchemistry of the Al/SiC interface
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The characteristics of the Al/SiC interface play a critical role in controlling the properties of SiC-reinforced aluminium composites and aluminium-brazed SiC ceramic joints. Recently, an investigation on the wettability of SiC single crystals by aluminiu
- Peteves,Tambuyser,Helbach,Audier,Laurent,Chatain
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- Effect of the processing methods on the formation of Al4C3IN SiCp/2024 Al composites
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SiCp/2024 Al composites were prepared using various processing techniques, such as the spray forming, thixoforming, and compocasting. The interfacial characterizations of these composites were performed using scanning electron microscopy, Auger
- Shin,Lee,Yoon,Lee
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- Some properties of aluminum carbide powder prepared by the pyrolysis of alkylaluminum
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Ultrafine aluminum carbide (Al4C3) powders with crystallite sizes of 3)3: TMAL), triethylaluminum (Al(C2H5)3: TEAL), triisobutylaluminum (Al(i-C4H9)3: TIBAL) at a temperature between 950° and 1100°C. Although the pyrolysis of TMAL produced Al4C3 at 950°C, the pyrolysis temperature of TEAL to produce Al4C3 was raised up to 1100°C. The pyrolysis of TIBAL at 1100°C produced not only crystalline Al4C3 but also amorphous oxycarbide. The TEAL-derived powder had the highest true density (2.89 g-cm-3 or 97% of the theoretical density) among the three kinds of powders.
- Itatani,Hasegawa,Aizawa,Howell,Kishioka,Kinoshita
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- Rapid, energy-efficient synthesis of the layered carbide, Al4C3
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The phase-pure binary aluminium carbide, Al4C3 can be synthesised in vacuo from the elements in 30 minutes via microwave heating in a multimode cavity reactor. The success of the reaction is dependent on the use of finely divided aluminium and graphite starting materials, both of which couple effectively to the microwave field. The yellow-brown powder product was characterised by powder X-ray diffraction, scanning electron microscopy/energy dispersive X-ray spectroscopy thermogravimetric-differential thermal analysis and Raman spectroscopy. Powders were composed of hexagonal single crystallites tens of microns in diameter (rhombohedral space group R3ˉm; Z = 3; a = 3.33813(5) ?, c = 25.0021(4) ?) and were stable to 1000 °C in air, argon and nitrogen. Equivalent microwave reactions of the elements in air led to the formation of the oxycarbide phases Al2OC and Al4O4C.
- Kennedy, Jennifer L.,Drysdale, Timothy D.,Gregory, Duncan H.
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- Contribution to the phase diagram Al4C3-AlN-SiC
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Compositions on the join Al4C3·2AlN-Al4C3·2SiC were investigated using X-ray diffraction and thermal analysis of hot-pressed bodies prepared from materials of various purities. The quaternary phase Al4C3·AlN·SiC was observed in samples prepared from the high-purity elements, but the ternary phases Al4C3·2AlN and Al4C3·2SiC were observed only in samples containing significant impurities. A projection onto the base triangle at 1860°C for the pseudoternary system Al4C3-AlN-SiC was constructed using X-ray diffraction, thermal analysis, and existing information in the literature.
- Oden,McCune
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- Structural characterization of a mechanical alloyed Al-C mixture
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The structural evolution during mechanical alloying elemental Al and graphite was characterized by X-ray diffractometry (XRD), Raman spectroscopy, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The grain size of Al and C both decreased with increasing milling time in the initial stage of milling, and then C diffused into Al to form a solid solution. Al4C3 might be produced either by annealing the Al-C solid solution or by MA the Al-C mixture for a longer time. The formation of Al4C3 was an exothermic process, but the released heat was not high enough to ignite the self-sustained reaction. Although the C peaks of the samples milled for longer than 30 h disappeared on the XRD patterns, the unreacted graphite and aluminum still existed in the samples even the mixture was milled for 100 h.
- Zhou,Li
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- Mechanism and kinetics of the chemical interaction between liquid aluminium and silicon-carbide single crystals
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Previous investigations of phase equilibria in the ternary system Al-C-Si have shown that silicon carbide is attacked by pure aluminium at temperatures higher or equal to 923 + 3 K and up to about 1600 K, according to the chemical reaction. 4Al+3SiC? Al4C3+3Si in the present work, a study has been carried out to obtain more detailed information on the mechanism and kinetics of this reaction. For that purpose, 6H silicon carbide platelets with broad Si (0001) and C (0001) faces were isothermally heated at 1000 K in a large excess of liquid aluminium. Characterization of the resulting samples by Auger electron spectroscopy (AES) and scanning electron microscopy (SEM) revealed that the reaction proceeds in both faces via a dissolution-precipitation mechanism. However, the polarity of the substrate surface strikingly influences the rate at which silicon carbide decomposes dissolution starts much more rapidly on the Si face than on the C face, but, while a barrier layer of aluminium carbide is formed on the Si face protecting it against further attack, the major part of the C face remains directly exposed to liquid aluminium and thus may continue to dissolve at a low but constant rate up to complete decomposition of A-SiC crystal.
- Viala,Bosselet,Laurent,Lepetitcorps
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- Properties of nano-structured pure Al produced by mechanical grinding and spark plasma sintering
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Air-atomised pure aluminium powder was mechanically grinded (MG) using a vibrational ball mill, and mechanically grinded powder was sintered by spark plasma sintering (SPS). Solid-state reactions of MG powder after various heat treatments were studied by X-ray diffraction (XRD). The mechanical properties of the SPS materials were evaluated by hardness and compression testing. Characterisations of the solid-state reactions between the MG powder and process control agent (PCA) after heating at temperatures from 573 to 873 K for 24 h suggested the following products. No solid-state reaction was observed after heating up to 573 K for 24 h. Formation of γ-Al2O3 occurred in the 4 h MG powder after heating at 773 K for 24 h, whereas the mixture of γ-Al2O3 and Al4C3 was observed in the 8 h MG powder after heating at 773 K for 24 h. The full density of the SPS material was obtained with the condition of applied pressure at 49 MPa at 873 K for 1 h. The Vickers hardness of the SPS material produced from no MG process and 64 h MG powders exhibited HV39 and HV159, respectively, and the SPS material based on no MG process and 8 h MG powders showed room temperature compressive proof stresses of 173 and 440 MPa, respectively.
- Kubota, Masahiro
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- Effect of particle additions on microstructure evolution of aluminium matrix composite
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The study investigates the influence of different fractions of particles (1, 2.5, 5, 8 and 10 vol.%) on microstructure of the as-extruded Al-Al 4C3 composite as well as on the microstructure evolution at elevated temperatures and after cooling to room temperature. The results indicate that all the materials exhibit a stable microstructure up to 500 °C. The excellent thermal stability is secured by the dispersed nano-particles that strengthen crystallite/grain boundaries by direct interaction of the particles with moving dislocations. In addition, the higher particle contents (8 and 10 vol.%) help to suppress the deformation texture of the hot extruded solids and refine the matrix microstructure to a nanometric scale resulting in a marked enhancing of dislocation density and consequently hardness.
- ?uri?inová, Katarína,?uri?in, Juraj,Orolínová, Mária,?uri?in, Martin
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- Investigation of different carbon nanotube reinforcements for fabricating bulk AlMg5 matrix nanocomposites
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Abstract AlMg5-based metal matrix composites were successfully fabricated using high energy planetary ball-milling and hot pressing. The influence of 6 types of carbon nanotubes (CNTs) with different properties was investigated for reinforcement. Over 3 fold increase in hardness and ultimate tensile strength was achieved with maximum values of 200 HV20 and 720 MPa respectively by varying CNT content from 0.5 to 5 vol%. The state, the dispersion as well as the reactivity of the different CNTs were investigated by Raman spectroscopy, X-Ray diffraction and microscopy. The CNTs were considered to be dispersed homogeneously, but were shortened due to high energy milling. No significant differences in mechanical performances could be observed depending either on the nature or on the agglomeration initial state of the investigated CNTs. The milling time has to be however adjusted to the CNT content as higher concentrations require a longer milling time for achieving dispersion of the nano-reinforcement.
- Kallip, Kaspar,Leparoux, Marc,Alogab, Khaled A.,Clerc, Steve,Deguilhem, Guillaume,Arroyo, Yadira,Kwon, Hansang
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- Equation of state of aluminum carbide Al4C3
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Quasi-hydrostatic compression of aluminum carbide, Al4C 3 has been studied to 6 GPa at room temperature using energy-dispersive X-ray powder diffraction with synchrotron radiation. A fit of the experimental p-V data to the Birch equation of state yields the values of the bulk modulus, B0, of 130(5) GPa and the first pressure derivative of the bulk modulus, B′0, of 4.6(9). The compression is found to be anisotropic, with the a-axis being more compressible than the c-axis.
- Solozhenko, Vladimir L.,Kurakevych, Oleksandr O.
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- On the synthesis of binary and ternary carbides in a modified domestic microwave oven
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By modifying a domestic microwave oven binary and ternary carbides were synthesized from the elements in an argon atmosphere. We succeded in preparing CaC2, Ca4Ni3C5 and MgM 3Cx (M = Ni, Co) within several minutes. Well crystallized product powders were obtainend with purities as high as 90% (CaC2, MgNi3Cx). In the case of MgNi3Cx our experiments show that a product with a high carbon content (x = 1) is only synthesized under optimized conditions (magnesium surplus, reaction time). This product exhibits the expected superconductivity with a critical temperature of approx. 6 K. The syntheses and possible structures of MgPdCxH y (x = 0.4-0.8, y = 0.4-2.3) and MgPtC0.06H0.32 are briefly discussed.
- Ahlers, Ruth,Ruschewitz, Uwe
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- Synthesis, structure, and vibrational spectra of Al3BC3, a carbidecarboborate of aluminum with linear (C=B=C)5- anions
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The highest negative charge of a 16-electron system known to date is shown by the CO2-analogous artion (C-B-C)5- in Al3BC3. This has been confirmed by the vibrational spectroscopic and structural characterization of this compound, which revealed the linearity and bond lengths given below. Al3BC3 can be regarded as the first carbidecarbidoborate of aluminum the first.
- Hillebrecht,Meyer
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- Conversion of basic dicarboxylate Al(III) complexes to aluminum carbide under a flow of argon
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The process of conversion of basic dicarboxylate Al(III) complexes Al(OH)(Cn+2H2nO4)·xH2O (n = 2, 3, 6) to aluminum carbide (Al4C3) under a flow of argon was investigated by powder XRD. The thermal decomposition of the glutarate complex (n = 3, AG) at 1100 °C gave a mixture of δ-alumina and carbon. As the calcination temperature was increased, the δ-alumina was first converted into α-alumina, then into aluminum monoxycarbide (Al2OC), and finally into the single phase of aluminum carbide (Al4C3) at 1600 °C. In contrast, the calcination of the succinate (n = 2, AS) complex at 1600 °C gave a mixture of δ-alumina, aluminum tetraoxycarbide (Al4O4C), Al2OC, and Al4C3, while the calcination of the suberate (n = 6, ASu) complex at 1600 °C gave a mixture of α-alumina, Al4O4C, and Al2OC. The difference in the products at 1600 °C was well explained by the relative amount of carbon produced by the thermal decomposition of the complexes. The reaction mechanism for the carburization of alumina to Al4C3 was suggested.
- Joo, Hyeong Uk,Jung, Woo-Sik
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- Microcellular Al2O3 ceramics from wood for filter applications
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Microcellular biomorphous Al2O3 was produced by Al-vapor infiltration in pyrolyzed rattan and pine wood-derived biocarbon preforms. At 1600°C the biocarbon preforms reacted with gaseous aluminum to form Al4C3. A
- Rambo, Carlos Renato,Andrade, Tarcisio,Fey, Tobias,Sieber, Heino,Martinelli, Antonio Eduardo,Greil, Peter
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- Synthesis and structure of T2-Al2MgC2
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The T1 and T2 crystalline varieties of the ternary carbide Al2MgC2 were synthesized by reacting graphite particles with Mg-Al melts at 930-1020 K. Below 1000 K, the T1 variety was predominant but little amounts of T2 were also present At 1000 K and above, only the T2 variety was obtained. Assuming a hexagonal close packing of the metal atoms, the crystal structure of T2-Al2MgC2 was determined by Rietveld refinemenent from X-ray powder diffraction data. / Elsevier,.
- Bosselet,Mentzen,Viala,Etoh,Bouix
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- Fabricating 2.5D SiCf/SiC composite using polycarbosilane/SiC/AI mixture for matrix derivation
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2.5D SiCf/SiC composites were produced by a modified polymer infiltration and pyrolysis process. Fine Al and SiC powders were first infiltrated into large inter-bundle pores. During pyrolytic decomposition of the polymer, the active Al filler reacts with small carbon-bearing polymer fragments, and reactive nitrogen atmosphere to form new phases of carbide or nitride. The volume expansion compensates for polymer shrinkage to a certain degree. The microstructural evolution and mechanical performances were characterized. The result indicates that the addition of Al fillers has significant influence on the mechanical properties of the composites. For the composite with Al loading, a proportional-limit stress of 380 MPa and a maximum stress of 441 MPa are achieved.
- Zhu, Yunzhou,Huang, Zhengren,Dong, Shaoming,Yuan, Ming,Jiang, Dongliang
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- Synthesis of Monophasic Al3BC3 Powder with Hexagonal Plate-like Morphology
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This paper describes the formation mechanism of monophasic Al3BC3 powder with hexagonal plate-like morphology using Al, B4C, and C powders in a stoichiometric ratio. For the synthesis of pure Al3BC3 by the conventional solid-state reaction method, it is important to avoid contamination from the starting powders. Thermogravimetry-differential thermal analysis curves and quantitative analysis by inductively coupled plasma-atomic emission spectroscopy revealed that there was no vaporization of the powder mixture during heating up to 1470 °C in a high-purity argon atmosphere. We found that the phases and Al3BC3 particle morphology after heating at 1800 °C strongly depended on the mixing conditions. In the case of a two-step process (remixing and reheating the sample), particles with random morphology were observed. On the other hand, well-faceted Al3BC3 particles were predominantly formed in a one-step process that involved heating after ball-milling for 24 h.
- Maki, Ryosuke S. S.,Matsumura, Shunta,Kida, Sota,Maeda, Tomoyuki,Taira, Hatsuo,Kusano, Yoshihiro
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p. 3493 - 3497
(2022/03/03)
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- Advances in manufacturing boron carbide-aluminum composites
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An infiltration method for preparing a boron carbide-aluminum (B4C-Al) composite was modified so as to reduce the processing temperature and time. Titanium metal and titanium-based compounds were added to B4C powders to enhance the wettability of the liquid aluminum on boron carbide skeletons. As expected, the time required for infiltration was significantly reduced on using the additives. Of these additives titanium metal was the most effective in facilitating aluminum infiltration. Another method, involving the heat treatment of boron carbide compacts at 1300°C for 1 h before infiltration, was attempted, and a significant improvement was gained. These findings show that the treatment modified the surface condition of boron carbide powders via the removal of oxides. An additional attempt was made to increase the boron carbide content of the system by using a bimodal powder mixture. A maximum green density of 78% was achieved by mixing fine particle size and coarse particle size powders. The infiltrated boron carbide composites prepared using a bimodal powder with a preinfiltration heat treatment of the compacts exhibited promising mechanical properties, such as a Vickers hardness (Hv) of 11 Gpa and an indentation toughness (KIC) in the range of 5-7.5 MPa·m1/2.
- Jung, Jinkwan,Kang, Shinhoo
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- Reduction of aluminum oxide by carbon at low pressures
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The interaction of aluminum oxide with carbon in the Al2O3-xC system (0 ≤ x ≤ 4.5) was studied in the pressure range p = 10-3-10-1 Pa. The phase compositions of solid residues and reduction products condensed in the "cold" section of the reaction chamber were determined. The thermodynamic calculations of the temperatures of the onset of reduction of Al2O3 by carbon at various partial pressures of CO were performed. It was shown that the reduction of aluminum oxide with the formation of gaseous products in the Al2O3-C system could be suppressed quantitatively if the partial pressure of CO was maintained above 2.1 × 103 Pa during calcining at temperatures below 2000 K.
- Ryabkov,Lekanova,Sporsheva
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p. 1237 - 1241
(2007/10/03)
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- Fourier transform infrared studies of propane pyrolysis over calcium aluminate melts
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Propane pyrolysis over calcium aluminate melts was carried out to evaluate carbon interactions with calcium, aluminum, and oxygen atoms. Infrared emission and attenuated total reflectance spectroscopies indicate that aluminum carbides and carbide oxides were formed early in the reaction as a result of carbon interactions with the melt. Moreover, time step emission spectra indicate that carbide oxides were formed before carbides, and that the carbon-melt reaction product carbon monoxide accompanied carbide formation. Calcium carbide formation was not observed. It is proposed that the initial appearance of carbides and carbide oxides is due to the preferential reaction between carbon and pentahedrally coordinated aluminum atoms. These results suggest that polymerization of alumina polyhedra rather than particle filler effects is responsible for the viscosity buildup and stream stabilization in the formation of calcium aluminate fibers by inviscid melt spinning.
- Fondeur,Mitchell
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p. 1045 - 1049
(2008/10/08)
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- Self-combustion reaction induced by mechanical activation of Al-Si-C powder mixtures
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The powders of Al, Si and C mixed in various molar ratios were ground ina planetary ball mill. When the mechanically activated mixtures were ex posed to air, they ignited spontaneously and the self-propagating high-temperature synthesis (SHS) took place in two successive steps. The finalproducts were aluminum nitride, aluminum carbide, aluminum oxycarbide, silicon carbide and alpha alumina. From the measurement of the lattice c onstant, it was found that aluminum nitride obtained is solid solutions in the system of AlN-Al2OC-SiC.
- Tsuchida, T.,Kitagawa, T.,Inagaki, M.
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- Successive high-temperature chlorine substitution and infrared matrix-isolation spectroscopy of methylaluminum chlorides
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Infrared spectra of the monomers (CH3)2AlCl and (CH3)AlCl2 have been obtained by thermal dissociation of the corresponding dimers followed by isolation in argon matrices. The Al-C bond is found to be of similar stability for all monomers (CH3)3-nAlCln (n = 0-2) while the strength of the Al-Cl bond decreases with higher alkyl contents. Several chlorine-bridged dimers, (CH3)6-nAl2Cln (n = 2-6), were identified in studies of dimeric dimethylaluminum chloride and methylaluminum dichloride. The experiments included elevated Knudsen cell temperatures, causing the following decompositions to occur: (CH3)4Al2Cl2 → (CH3)3AlCl3 → trans-(CH3)2Al2Cl4 (350-450°C) and (CH3)2Al2Cl4 → (CH3)Al2Cl5 → Al2Cl6 (550°C). These cracking reactions are more prominent than the mere dissociations. On the basis of the valence force field of Al2Cl6 a good agreement between calculated and observed skeletal frequencies was achieved for the dimers. Frequencies were found to fall within narrow ranges for skeletal stretching modes involving the same atoms or groups.
- Rytter, Erling,Kvisle, Steinar
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p. 3796 - 3804
(2008/10/08)
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