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        검색결과 236

        101.
        2007.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Bulk metallic glass (BMG) composite was fabricated by consolidation of milled metallic glass composite powders. The metallic glass composite powder was synthesized by a controlled milling process using the Cu-based metallic glass powder blended with 30 vol% Zr-based metallic glass powders. The milled composite powders showed a layered structure with three metallic phases, which is formed as a result of mechanical milling. By spark plasma sintering of milled metallic glass powders in the supercooled liquid region, a fully dense BMG composite was successfully synthesized.
        4,000원
        102.
        2007.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Ultrasonic-milling of metal oxide nanopowders for the preparation of tungsten heavy alloys was investigated. Milling time was selected as a major process variable. XRD results of metal oxide nanopowders ultrasonic-milled for 50 h and 100 h showed that agglomerate size reduced with increasing milling time and there was no evidence of contamination or change of composition by impurities. It was found that nanocomposite powders reduced at in a hydrogen atmosphere showed a chemical composition of 93.1W-4.9Ni-2.0Fe from EDS analysis. Hardness of sintered part using 50 h and 100 h powder samples was 399 Hv and 463 Hv, respectively, which is higher than the that of commercial products (330-340 Hv).
        4,000원
        103.
        2006.10 KCI 등재 구독 인증기관·개인회원 무료
        104.
        2006.09 구독 인증기관·개인회원 무료
        In the present work, the influence of the ball-milling time, milling atmosphere and weight ratio of ball to powder on characteristics of was studied. Results show that, the grain sizes of the and CuO in the ball-milled powder mixture were significantly decreased with increasing the milling time. Those of each oxide ball-milled in Argon and Hexane atmosphere for 30 and 20 hour were about 98 and 84 nm, respectively. After milling of 20 hour in Hexane as PCA, the powder had a homogeneously mixed structure and the average size of powders was determined to about 230nm.
        105.
        2006.09 구독 인증기관·개인회원 무료
        [ ] nanocomposite powders with a nominal composition of were prepared by HDDR combined with mechanical milling. The microstructure was studied by Mossbauer spectrometry and TEM. The magnetic properties were investigated by VSM using bonded magnet samples. The results showed that the annealing temperature had significant influence on both the recombination kinetics and the grain size of the and phases, and the bonded magnets presented the best magnetic properties when the nanocomposite powders were prepared by annealing at for 30 min.
        106.
        2006.09 구독 인증기관·개인회원 무료
        Study about the feasibility and effect of high-energy ball milling on a specific Mg alloy under protection medium of alcohol was presented via comparing with conventional vacuum milling. More fine particles with wider powder size distribution but more irregular shape were shown of the powder milled under alcohol. No obvious oxide was revealed from the two kinds of Mg alloy powders with limited milling time. And since slip induced in a preferential direction, the (002) texture was formed in the Mg alloy powders at the initial stage of alcohol milling. More O and Fe contaminants were introduced into the powders milled under alcohol according to the EDS analysis.
        107.
        2006.09 구독 인증기관·개인회원 무료
        Dispersion-strengthened copper with was produced by ball-milling and spark plasma sintering (SPS).Ball-milling was performed at a rotation speed of 300rpm for 30 and 60min in Ar atmosphere by using a planetary ball mill (AGO-2). Spark-plasma sintering was carried out at for 5min under vacuum after mechanical alloying. The hardness of the specimens sintered using powder ball milled for 60min at 300rpm increased from 16.0 to 61.8 HRB than that of specimen using powder mixed with a turbular mixer, while the electrical conductivity varied from 93.40% to 83.34%IACS. In the case of milled powder, hardness increased as milling time increased, while the electrical conductivity decreased. On the other hand, hardness decreased with increasing sintering temperature, but the electrical conductiviey increased slightly
        108.
        2006.09 구독 인증기관·개인회원 무료
        Mn-Fe oxide and Mn-Fe oxide/(50wt%/50wt%) were prepared by ball milling method. XRD data of the prepared samples revealed that hematite and ferrite phase coexisted. Water splitting at 1273K, after thermal reduction at 1573K, was performed 4 times for the samples. Hydrogen production amount was analyzed by GC with TCD detector. Water splitting capacity of Mn-Fe oxide was improved by ball milling with .
        109.
        2006.09 구독 인증기관·개인회원 무료
        In present work, manufacturing technologies of titanium hydride powder were studied for recycling of titanium tuning chip and for this, attrition ball milling was carried out under H2 pressure of 0.5 MPa. Ti chips were completely transformed into TiH2 within several hundred seconds. Dehydrogenation process TiH2 powders is consist of two reactions: one is reaction of TiH2 to TiHx and the other decomposition of TiHx to Ti and H2. The former reaction shows relatively low activation energy and it is suggested that the reaction is caused by introduction of defects due to milling.
        110.
        2006.09 구독 인증기관·개인회원 무료
        Li reacts with N2 at room temperature. In order to activate Li, the mechanical milling of Li with stable metal oxide, namely, Al2O3 and MgO, using a high energy vibrating ball mill was performed. In the case of Li-MgO system, it reacts with N2, but hardly reacts with O2. The reaction with N2 generally produces Li3N, while for some vigorous reactions the Mg3N2 is produced as the major phases. In the case of Li-Al2O3 system, reactivities with both N2 and O2 are high. The difference is explained in terms of the reaction mechanism and the Li state.
        113.
        2006.09 구독 인증기관·개인회원 무료
        The present work studies the influence of high-energy milling (HEM) and sintering cycle of Ti and Al powders on the obtainment of TiAl. This study shows that HEM modifies the diffusion processes during the sintering stage. The samples were obtained by cold uniaxial and isostatic pressing, pre-sintered at different temperatures, and heated up to the sintering temperature. This study also shows the effect of powder additions processed by HEM on the sintering behavior of elemental Ti and Al powders.
        119.
        2005.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The structural and magnetic properties of nanostructued alloy powders were investigated. Commercial alloy powders (Hoeganaes Co., USA) with purities were used to fabricate the nanostructure Fe-Si alloy powders through a high-energy ball milling process. The alloy powders were fabricated at 400 rpm for 50 h, resulting in an average grain size of 16 nm. The nanostructured powder was characterized by fcc and hcp phases and exhibited a minimum coercivity of approximately 50 Oe
        4,000원