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Mechanical Milling (mechanical + milling)
Selected AbstractsStructural Evolution during Reactive Mechanical Milling of TiC/Ti-Al Nanocomposites,ADVANCED ENGINEERING MATERIALS, Issue 7 2009Dongdong Gu The microstructural development of TiC/Ti-Al nanocomposites prepared by mechanical milling of Ti, graphite, and Al powders is investigated. The structures and morphologies of the nanocomposites milled at various periods are determined by XRD, SEM, TEM and EDX-spectroscopy techniques. The mechanisms for the formation of TiC nanoparticles and Ti-Al solid solution are elucidated based on these experimental results. [source] Technical Cost Modeling for the Mechanical Milling at Cryogenic Temperature (Cryomilling),ADVANCED ENGINEERING MATERIALS, Issue 8 2004J. Ye Cryomilling is one of the few technologies available to fabricate a large quantity of nanostructured materials. No matter how exciting and promising a technology is, its ultimate realization is invariably dependent on economic success. Technical cost modeling was employed in this paper to analyze the processing cost of cryomilling. The results demonstrated that cryomilling has the potential to be commercially economical to fabricate nanostructured materials. [source] Superplasticity and high temperature deformation behaviour in nano grain Tungsten compactsMATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 4-5 2008K. Ameyama Abstract Nano grain tungsten is fabricated by Mechanical Milling (MM) process, and its grain growth behavior and high temperature deformability is investigated. As a result, a nano grain structure, whose grain size is approximately 20 nm or less, is obtained after MM for 360ks. Those nano grains demonstrate an irregular grain boundary structure, i.e., "non-equilibrium grain boundary", and they change to a smooth grain boundary structure by annealing at 1023 K for 3.6 ks. Compacts with nano grain structure indicate superior sintering property even at 1273 K (0.35 Tm). Rhenium addition prevents grain growth during sintering and thus the compacts indicate a further improvement in deformability. The compact is composed of equiaxed grain, whose grain size is 420 nm, and has low dislocation density even after the large deformation. The strain rate sensitivity, i.e., m-value, of 0.41 is obtained in the W-Re compact at 1473 K. Those results strongly imply that the nano grain W-Re compacts show superplasticity at less than half of the melting temperature, i.e., 1473 K (0.42 of the solidus temperature). [source] ChemInform Abstract: Rapid Synthesis of Bi and Sb Sulfides Using Electric Discharge Assisted Mechanical Milling.CHEMINFORM, Issue 30 2008A. Calka Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Synthesis of Disordered Pyrochlores, Ln2Ti2O7 (Ln: Y, Gd and Dy), by Mechanical Milling of Constituent Oxides.CHEMINFORM, Issue 29 2005Antonio F. Fuentes Abstract For Abstract see ChemInform Abstract in Full Text. [source] Preparation and evaluation of composite electromagnetic wave absorbers made of aluminum fine particles dispersed in polystyrene mediumELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 1 2010Norizumi Asano Abstract We developed composite electromagnetic wave absorbers consisting of dispersed aluminum fine particles in a polystyrene medium and evaluated their properties in order to realize single-layer electromagnetic wave absorbers with good absorption in the gigahertz region. Polystyrene particles with two diameters (approximately 200 ,m and 1 ,m) and fine aluminum particles were mixed by mechanical milling. The mixture was heated above the melting point of polystyrene and then cooled naturally in air. The frequency characteristics of the complex relative permeability and the complex relative permittivity were calculated from the values of the scattering parameters of a coaxial line loaded with a sample of a toroidal-core shape. Both the diamagnetism and the magnetic loss increased in proportion to the volume mixing ratios of aluminum particles up to approximately 34 vol for samples made of polystyrene particles with approximately 200 ,m or 1,m diameter. The diamagnetism was almost frequency-independent and the magnetic loss decreased with increasing frequency for all samples. These results were in agreement with qualitative theoretical prediction. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 93(1): 30, 40, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10169 [source] Structural Evolution during Reactive Mechanical Milling of TiC/Ti-Al Nanocomposites,ADVANCED ENGINEERING MATERIALS, Issue 7 2009Dongdong Gu The microstructural development of TiC/Ti-Al nanocomposites prepared by mechanical milling of Ti, graphite, and Al powders is investigated. The structures and morphologies of the nanocomposites milled at various periods are determined by XRD, SEM, TEM and EDX-spectroscopy techniques. The mechanisms for the formation of TiC nanoparticles and Ti-Al solid solution are elucidated based on these experimental results. [source] Dispersion of nanoscale BaTiO3 suspensions by a combination of chemical and mechanical grinding/mixing processesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Kuo-Liang Ying Abstract The colloidal stability of aqueous nanometer- and micrometer-scale barium titanate (BaTiO3) utilizing poly (methacrylic acid) (PMAA-Na) and polyacrylamide/(,- N,N -dimethyl- N -acryloyloxyethyl)ammonium ethanate (PDAAE) was investigated. In addition to chemical dispersants, the effects of mechanical milling using either conventional ball milling or nanogrinding/-mixing on the dispersion of BaTiO3 suspensions were also studied. Characterization of the particle size distribution (d50), viscosity, and morphology of BaTiO3 particles in the suspensions revealed that a sole chemical dispersant or mechanical milling was insufficient to achieve nanometer-scale dispersion. The best dispersion results were obtained with a combination of PMAA-Na dispersant and nanogrinding/-mixing, which could provide sufficient electronic repulsive force and shear force to disperse the 80-nm BaTiO3 powders uniformly in the aqueous suspension. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source] Preparation of rubber composites from ground tire rubber reinforced with waste-tire fiber through mechanical millingJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007Xin-Xing Zhang Abstract Composites made from ground tire rubber (GTR) and waste fiber produced in tire reclamation were prepared by mechanical milling. The effects of the fiber content, pan milling, and fiber orientation on the mechanical properties of the composites were investigated. The results showed that the stress-induced mechanochemical devulcanization of waste rubber and the reinforcement of devulcanized waste rubber with waste-tire fibers could be achieved through comilling. For a comilled system, the tensile strength and elongation at break of revulcanized GTR/fiber composites reached maximum values of 9.6 MPa and 215.9%, respectively, with 5 wt % fiber. Compared with those of a composite prepared in a conventional mixing manner, the mechanical properties were greatly improved by comilling. Oxygen-containing groups on the surface of GTR particles, which were produced during pan milling, increased interfacial interactions between GTR and waste fibers. The fiber-filled composites showed anisotropy in the stress,strain properties because of preferential orientation of the short fibers along the roll-milling direction (longitudinal), and the adhesion between the fiber and rubber matrix was improved by the comilling of the fiber with waste rubber. The proposed process provides an economical and ecologically sound method for tire-rubber recycling. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 4087,4094, 2007 [source] Synthesis, Microstructure, and Mechanical Properties of a Novel Ti2AlC/TiC/Al2O3In Situ CompositeJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2006D. L. Zhang This paper describes a novel process for synthesizing a Ti2AlC/TiC/Al2O3in situ composite. This route utilizes TiO2, carbon, and Al powders as raw materials, and involves high-energy mechanical milling and powder sintering. The Ti2AlC/TiC/Al2O3 bulk in situ composite produced has a phase composition of Ti2AlC,20 vol% TiC,35 vol% Al2O3 with fine Al2O3 particles (size: 0.5,15 ,m) embedded in a Ti2AlC/TiC matrix. The Ti2AlC grains exhibit a nanometer scale lamellar structure, and most of the Al2O3 grains contain fine cubic TiOmC1,m precipitates (size: 10,200 nm). The average hardness and bending strength of the composite are in the ranges of 11,12.5 GPa and 380,440 MPa, respectively. Here we have demonstrated that the mechanical performance (mainly hardness and bending strength) of the composite is directly correlated with the size of the Al2O3 particles present in the as-fabricated in situ composite. [source] Spark-Plasma Sintering of Silicon Carbide Whiskers (SiCw) Reinforced Nanocrystalline AluminaJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2004Guo-Dong Zhan The combined effect of rapid sintering by spark-plasma-sintering (SPS) technique and mechanical milling of ,-Al2O3 nanopowder via high-energy ball milling (HEBM) on the microstructural development and mechanical properties of nanocrystalline alumina matrix composites toughened by 20 vol% silicon carbide whiskers was investigated. SiCw/,-Al2O3 nanopowders processed by HEBM can be successfully consolidated to full density by SPS at a temperature as low as 1125°C and still retain a near-nanocrystalline matrix grain size (,118 nm). However, to densify the same nanopowder mixture to full density without the benefit of HEBM procedure, the required temperature for sintering was higher than 1200°C, where one encountered excessive grain growth. X-ray diffraction (XRD) and scanning electron microscopy (SEM) results indicated that HEBM did not lead to the transformation of ,-Al2O3 to ,-Al2O3 of the starting powder but rather induced possible residual stress that enhances the densification at lower temperatures. The SiCw/HEBM,-Al2O3 nanocomposite with grain size of 118 nm has attractive mechanical properties, i.e., Vickers hardness of 26.1 GPa and fracture toughness of 6.2 MPa·m1/2. [source] A Novel Processing Route to Develop a Dense Nanocrystalline Alumina Matrix (<100 nm) Nanocomposite MaterialJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2003Guo-Dong Zhan A dense 3-mol%-yttria-stabilized tetragonal zirconia polycrystalline (3Y-TZP) toughening alumina matrix nanocomposite with a nanocrystalline (<100 nm) matrix grain size has been successfully developed by a novel processing method. A combination of very rapid sintering at a heating rate of 500°C/min and at a sintering temperature as low as 1100°C for 3 min by the spark-plasma-sintering technique and mechanical milling of the starting ,-Al2O3 nanopowder via a high-energy ball-milling process can result in a fully dense nanocrystalline alumina matrix ceramic nanocomposite. The grain sizes for the matrix and the toughening phase were 96 and 265 nm, respectively. A great increase in toughness almost 3 times that for pure nanocrystalline alumina has been achieved in the dense nanocomposite. Ferroelastic domain switching without undergoing phase transformation in nanocrystalline t -ZrO2 is likely as a mechanism for enhanced toughness. [source] Magnetic properties of screen-printed (Y0.5Sm0.5)Co5 magnet arraysPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2007D. Bueno-Baques Abstract (Y0.5Sm0.5)Co5 magnet arrays of square ,dots of 300 ,m were prepared by screen printing. A well controlled paste like ink prepared with the (Y0.5Sm0.5)Co5 nanoparticles and a mixture of organic solvent and polymer was used to print different pattern arrays. (Y0.5Sm0.5)Co5 nanoparticles were obtained by mechanical milling starting from arc melted ingots and heat treated in Ar atmosphere. Two different heat treatment were considered, resulting in powders with different magnetic properties. The microstructure of the magnet arrays was studied by scanning electron microscopy (SEM). An isotropic homogeneous distribution of the nanoparticles inside the ,dots was observed. The final shape of the ,dots in the array was found to be highly dependent on the squeeze pressure and speed over the mesh. Magnetic properties were studied by pulsed field magnetometry and vibrating sample magnetometry at room temperature. The micro size arrays showed lower saturation magnetization and a slightly increase in the coercive field. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The influence of mechanical alloying on the structural and physical properties of YNi4B compoundPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2003M. Timko Abstract We have investigated the influence of mechanical milling on structural changes, magnetic and superconducting properties of YNi4B compound. This compound crystallizes in a hexagonal structure with the P6/mmm space group. Magnetic measurements have shown that originally prepared sample exhibits superconducting behaviour below 12 K and above this temperature the sample is paramagnetic. The great decrease of intensity and broadening of diffraction lines have been detected after milling as a consequence of sample amorphisation. [source] Composition influence on positron annihilation parameters in ZnO-based nanocrystal semiconductor powdersPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2007L. C. Damonte Abstract Zn1,xMgxO powders at various compositions were obtained by mechanical milling from the binary oxides. The progressive incorporation of Mg atoms into the ZnO lattice was monitored by X-ray diffraction (XRD). The evolution of annihilation parameters with milling time and composition were analyzed and related to the possible types of mechanical and substitutional induced defect present. It was concluded that the average lifetime constitute a useful parameter to sense the complete cation substitution in the wurtzite structure. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effect of high-energy vibro-milling of filler on the mechanical properties of filled high-density polyethylenePOLYMER COMPOSITES, Issue 3 2003Shaoyun Guo The effect of high-energy mechanical milling of CaCO3 (calcium carbonate) and STC (a mixture of sericite, tridymite and cristobalite) on mechanical properties, rheological and dynamical mechanical behavior of high-density polyethylene (HDPE)/CaCO3 and HDPE/STC was studied through SEM (scanning electron microscope), DMTA (dynastic mechanical test analysis), mechanical and melt rheological properties tests. The experimental results show that addition of fillers treated by coupling agent and vibromilling to HDPE makes the impact strength of HDPE greatly increased. The impact strength of HDPE/treated CaCO3 (60/40) and HDPE/treated STC (60/40) is ca. 4 and 3 times respectively as high as that of HDPE. The SEM micrographs of impact fractured surfaces of treated fillers filled HDPE show extensive plastic deformation of HDPE matrix, indicating that the plastic deformation of matrix induced by the treated fillers is the main contribution for absorbing a great amount of impact energy. This is the reason why the impact strength of HDPE greatly increases with addition of coupling agent and vibromilling treated fillers. The intensity of , relaxation peak of HDPE in HDPE/treated CaCO3 on tan, vs. temperature curve increases and the peak shifts to higher temperature due to its stronger interface interaction as compared with that of HDPE/untreated CaCO3. [source] Experimental and Theoretical Investigation of the Room-Temperature Photoluminescence of Amorphized Pb(Zr,Ti)O3CHEMPHYSCHEM, Issue 8 2005Emmanuelle Orhan Dr. Abstract Ultrafine PbZr0.20Ti0.80O3 was amorphized through high-energy mechanical milling. The structural evolution through the amorphization process was accompanied by various characterization techniques, such as X-ray diffraction, Fourier-transformed IR spectroscopy (FTIR), high-resolution transmission electron microscopy (HR-TEM), and Raman spectroscopy. A strong photoluminescence was measured at room temperature for amorphized PbZr0.20Ti0.80O3, and interpreted by means of high-level quantum mechanical calculations in the density functional theory framework. Three periodic models were used to represent the crystalline and amorphized PbZr0.20Ti0.80O3, and they allowed the calculation of electronic properties that are consistent with the experimental data and that explain the appearance of photoluminescence. [source] | ||||||||||||||||