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  • 1
    Electronic Resource
    Electronic Resource
    Improvement of Cutting Performance of Silicon Nitride Tool by Adherent Coating of Thick Diamond Film (1997)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 80 (1997), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A thick diamond film was coated using two-stage microwave plasma CVD in the COH, system on a pretreated silicon nitride substrate for a cutting tool. The effects of acid treatment and microflawing treatment of the substrate on adherence of the film and cutting performance were investigated as well as the effects of two-stage CVD conditions. The combination of substrate pretreatment in a hot, strong acid solution of HF and HNO3 and subsequent ultrasonic microflawing pretreatment with diamond grains resulted in the anchored deposition of CVD diamond into the micropores in the silicon nitride substrate. An excellent adherence of the diamond film to the substrate was attained by the two-stage CVD, which consists of a first CVD of fine diamond grains into the micropores and a second higher rate CVD of thick diamond film (thickness 〉30 pm). A dense layer composed of diamond-like carbon and silicon nitride was formed deep in the boundary region of the substrate during long CVD treatment. Long tool life of the silicon nitride chip coated with a thick diamond film was verified by a milling test using Al-20 wt% Si alloy as the work material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1997.tb02809.x
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  • 2
    Electronic Resource
    Electronic Resource
    B6O–c-BN Composites Prepared by High-Pressure Sintering (2000)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 83 (2000), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: High-pressure sintering behavior in the B6O–c-BN system was investigated using in-laboratory-synthesized B6O and commercially available c-BN powders (with an average grain size of 0.5, 3, or 6 μm). No reaction occurred between the two components under the high-pressure (4–6 GPa) and high-temperature (1500°–1800°C) conditions that have been investigated. Well-dispersed, sintered B6O–x(c-BN) composites (wherex= 0–60 vol%) of almost-full density were prepared by sintering at a pressure of 6 GPa and temperature of 1800°C for 20 min. The maximum Vickers microhardness (46 GPa) of these composites was attained by adding 40 vol%c-BN with an average grain size of 0.5 μm. The fracture toughness of these composites increased as the c-BN content increased; the maximum fracture toughness (1.5–1.8 MPa.m1/2) was observed for x= 40–60 vol%. Crack deflection along the B6O–c-BN grain boundary contributed to increasing the fracture toughness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.2000.tb01224.x
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  • 3
    Electronic Resource
    Electronic Resource
    Spin Coating of a Ca(Ti,Fe)O3 Dense Film on a Porous Substrate for Electrochemical Permeation of Oxygen (1997)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 80 (1997), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A dense Ca(Ti0.75Fe0.25)O3−α (Ca(Ti,Fe)O3) film, which is a mixed conductor of oxide ions and electrons/holes, was prepared on a porous CaTiO3 substrate by a spin-coating method. The calcined Ca(Ti,Fe)O3 powder with 2–3 μm grain sizes was mixed with a dispersant in ethanol to form the slurry for spin coating. A uniform Ca(Ti,Fe)O3 green film was obtained at 1000–1500 rpm on the rotating porous CaTiO3 substrate, which had an average pore diameter of a few micrometers. The optimum sintering conditions for the spin-coated films were a soaking temperature of 1235°C and a holding time of 2 h, in air. A dense, sintered Ca(Ti,Fe)O3 film }20–50 μm thick was prepared by repeating the coatingsintering process. The gas-tight film prepared on the porous substrate exhibited higher electrochemical permeation of oxygen at an operating temperature of 1000°C compared with that of thicker, sintered Ca(Ti,Fe)O3 disks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1997.tb02992.x
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  • 4
    Electronic Resource
    Electronic Resource
    Resource Recovery of WC-Co Cermet Using Hydrothermal Oxidation Technique (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 280-283 (Feb. 2007), p. 1479-1484 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: WC-Co cermet is widely used in industrial applications such as cutting tools, dies, wear parts and so on. It is of great importance to establish the recycling process for the precious metal resources contained in WC-Co cermet, because all these metals used in Japan are imported. In this paper we reported a hydrothermal oxidation technique using nitric acid for the reclamation of WC and Co. The WC-Co cermet specimens with various WC particle sizes and Co contents were hydrothermally treated in HNO3 aqueous solutions at temperatures of 110-200°C for durations of 6-240 h. The Co was preferentially leached out into the acidic solution, while the WC was oxidized to insoluble WO3 hydrate which was subsequently separated by filtration. The hydrothermal treatment parameters such as solvent concentrations, treatment temperatures, holding time were optimized in respect to different kinds ofWC-Co cermets. A hydrothermal oxidation treatment in 3M HNO3 aqueous solution at 150°C for 24 h was capable of fully disintegrating the cermet chip composed of coarse WC grains of 1-5 µm in size with 20 wt% of Co as binder. While the more oxidation resistant specimen composed of fine WC grains of 0.5-1.0 µm in size with 13 wt% of Co, was completely disintegrated by a treatment in 7 M HNO3 aqueoussolution at 170°C for 24 h. The filtered solid residues were composed of fine WO3.0.33H2O powder and a small amount of WO3. The recovered WO3.0.33H2O powder can be easily returned to the industrial process for the synthesis of WC powder so that the overall recycling cost can be possibly lowered
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/49/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.280-283.1479.pdf
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  • 5
    Electronic Resource
    Electronic Resource
    Positron Lifetime Study on Degradation of TiCrV Hydrogen Storage Alloy (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 607 (Nov. 2008), p. 122-124 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Using positron lifetime spectroscopy, we examined the evolution of defects in the Ti24Cr36V40 alloy prepared by arc-melting method during hydriding cycles. We found that the positron lifetime increases with increasing the pressure swing cycles. This behavior is well correlated with the degradation of hydrogen transfer change with the pressure swing cycles. The prolonged positron lifetime is attributed to dislocation-related defects. Both dislocations and vacancies bound at dislocations may act as positron trapping centers. After the heat treatment at 400oC, a partial recovery of positron lifetime was observed
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/20/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.607.122.pdf
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of starting carbon and solvent-catalyst on the reaction sintering of diamond (1988)
    Springer
    Journal of materials science 23 (1988), S. 2877-2881 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Polycrystalline diamond sintered compact was prepared under high pressure and temperature conditions (7 GPa, 1700° C, 10 to 15 min) from purified natural graphite (NG) or graphitized pitch coke (GPC) using iron, cobalt or nickel as the catalytic active metal and titanium or zirconium as the solvent metal. The effects of the combinations of starting carbon and solvent-catalyst on the transformation behaviour and morphology of the converted diamond were investigated in relation to the starting powder compositions. Diamond crystals converted from NG tended to have euhedral habits, when twin crystals were occasionally found due to a relatively rapid conversion and growth rate of diamond. On the other hand, a skeletal structure of diamond was easily formed by a mild conversion from GPC in the 15 to 30 vol% (∼ 40 to 60 wt%) nickel solvent-catalyst. The degree of catalytic action in the 8A group of 3d transition metals for the GPC system was in the order: Ni ⩾ Co 〉 Fe. The grain growth of the converted diamond was depressed by the addition of 4A transition metals (titanium or zirconium) which results in the fine-grained and homogeneous sintered microstructure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00547462
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  • 7
    Electronic Resource
    Electronic Resource
    Preparation of TiB2 sintered compacts by hot pressing (1990)
    Springer
    Journal of materials science 25 (1990), S. 533-536 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A sintered compact of titanium diboride (TiB2) was prepared by hot pressing of the synthesized TiB2 powder, which was obtained by a solid-state reaction between TiN and amorphous boron. Densification of the sintered compact occurred at 20 MPa and 1800° C for 5 to 60 min with the aid of a reaction sintering, including the TiB2 formation reaction between excess 20 at % amorphous boron in the as-synthesized powder (TiB2 + 0.2B) and intentionally added 10 at % titanium metal. A homogeneous sintered compact of a single phase of TiB2, which was prepared by hot pressing for 30 min from the starting powder composition [(TiB2 + 0.2B) + 0.1 Ti], had a fine-grained microstructure composed of TiB2 grains with diameters of 2 to 3 μm. The bulk density was 4.47 g cm−3, i.e. 98% of the theoretical density. The microhardness, transverse rupture strength and fracture toughness of the TiB2 sintered compact were 2850 kg mm−2, 48 kg mm−2 and 2.4 MN m−3/2, respectively. The thermal expansion coefficient increased with increasing temperature up to 400° C and had a constant value of 8.8 x 10−6 deg−1 above 500° C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00714070
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  • 8
    Electronic Resource
    Electronic Resource
    Preparation of nickel and Ni-Zn ferrite films by thermal decomposition of metal acetylacetonates (1986)
    Springer
    Journal of materials science 21 (1986), S. 3677-3680 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Nickel and Ni-Zn ferrite (Ni1−x Zn x Fe2O4) films were prepared on various substrates (quartz glass, MgO single crystal, etc.) by thermal decomposition of metal acetylacetonates (Ni (acac)2 · 2H2O, Zn (acac)2 · 2H2O and Fe (acac)3). Typical decomposition and heat treatment conditions for obtaining a single phase of NiFe2O4 film were as follows: evaporation temperature of Ni-Fe complexes: 230°C, the mole concentration of Fe (acac)3,R (%) = Fe (acac)3/(Fe (acac)3 + Ni (acac)2 · 2H2O) = 33, substrate temperature: 330 to 550° C, and heat treatment of the as-grown film: 800 to 1000° C, 1 h. Ni1−x Zn x Fe2O4 films were obtained by controlling the compositionR in Ni-Fe complexes and the evaporation temperature of Zn (acac)2 · 2H2O. The Ni-Zn ferrite film at the compositionx = 0.37 (Ni0.63Zn0.37Fe2O4) gave the maximum saturation magnetizationσ s = 60 emu g−1 and the coercive forceHc ≈ 25 Oe. These films showed a magnetic anisotropy which makes the magnetization easy parallel to film surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02403020
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  • 9
    Electronic Resource
    Electronic Resource
    Preparation of nickel and Ni-Zn ferrite films by thermal decomposition of metal acetylacetonates (1986)
    Springer
    Journal of materials science 21 (1986), S. 3677-3680 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Nickel and Ni-Zn ferrite (Ni1−x Zn x Fe2O4) films were prepared on various substrates (quartz glass, MgO single crystal, etc.) by thermal decomposition of metal acetylacetonates (Ni (acac)2 · 2H2O, Zn (acac)2 · 2H2O and Fe (acac)3). Typical decomposition and heat treatment conditions for obtaining a single phase of NiFe2O4 film were as follows: evaporation temperature of Ni-Fe complexes: 230°C, the mole concentration of Fe (acac)3,R (%) = Fe (acac)3/(Fe (acac)3 + Ni (acac)2 · 2H2O) = 33, substrate temperature: 330 to 550° C, and heat treatment of the as-grown film: 800 to 1000° C, 1 h. Ni1−x Zn x Fe2O4 films were obtained by controlling the compositionR in Ni-Fe complexes and the evaporation temperature of Zn (acac)2 · 2H2O. The Ni-Zn ferrite film at the compositionx = 0.37 (Ni0.63Zn0.37Fe2O4) gave the maximum saturation magnetizationσ s = 60 emu g−1 and the coercive forceHc ≈ 25 Oe. These films showed a magnetic anisotropy which makes the magnetization easy parallel to film surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00553818
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  • 10
    Electronic Resource
    Electronic Resource
    Effect of ambient pretreatment of graphite and solvent-catalyst on diamond formation (1987)
    Springer
    Journal of materials science 22 (1987), S. 1081-1086 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Diamond was formed from purified natural graphite under high pressure and temperature conditions (7 G Pa, 1700° C) using a solvent-catalyst in the unary (Fe) or binary (Fe-Ti) system. The effect of an ambient pretreatment of the starting mixed powder (graphite and solvent-catalyst) was investigated in relation to the formation and grain growth of diamond. An initial desorption of adsorbed water vapour or harmful gases from the starting powder in vacuum (2 × 10−5 torr) at higher temperatures (〉400° C) was required in order to increase the conversion ratio from graphite to diamond. The subsequent ambient pretreatment at 1000° C in different atmospheres was found to affect the grain growth process of diamond. The depression of grain growth was confirmed in both cases of pretreatments in vacuum (2 × 10−5 torr) and in an argon atmosphere (1 × 10−3 or 760 torr). The diamond grains were discrete in the vacuum pretreatment, while a particle joining between the diamond grains was promoted in the argon pretreatment. The pretreatment in an N2 atmosphere (1 × 10−3 or 760 torr) tended to accelerate the grain growth of diamond.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01103554
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