| 1. |
- Ahlen, N., et al.
(författare)
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On the carbothermal vapour-liquid-solid (VLS) mechanism for TaC, TiC, and TaxTi1-xC whisker growth
- 2000
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Ingår i: Journal of the European Ceramic Society. - 0955-2219 .- 1873-619X. ; 20:14-15, s. 2607-2618
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Tidskriftsartikel (refereegranskat)abstract
- The growth of TaC, TiC and TaxTi1-xC whiskers has been studied in some detail. The whiskers were synthesised via a vapour-liquid-solid (VLS) growth mechanism in the temperature range 1220-1400 degreesC. The starting materials were Ta2O5, TiO2, C, NaCl, and a catalyst metal (Ni, Co, Fe, and Cu were tested). The main reaction during synthesis was a carbothermal reduction of Ta2O5 and TiO2, and NaCl was added to form the oxochlorides and chlorides of Ta and Ti that account for the transport to the catalyst metal. The syntheses were made in a protecting Ar atmosphere. From experiments interrupted after different times at the synthesis temperature it is clear that sodium tantalates form as intermediate products, whereas sodium titanates cannot be identified. Only metals that are able to dissolve the elements building up the whiskers work as catalysts. Whisker growth starts either from a catalyst droplet in contact with carbon or from an oxide particle in contact with both catalyst metal and carbon. For TaC and TaxTi1-xC the only growth direction observed is [100], while TiC may grow either along [100] or along [111].
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| 2. |
- Frisk, K., et al.
(författare)
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Development of a database for cemented carbides : Thermodynamic modeling and experiments
- 2001
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Ingår i: Journal of phase equilibria (Print). - 1054-9714 .- 1544-1032. ; 22:6, s. 645-655
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Tidskriftsartikel (refereegranskat)abstract
- A new database, for thermodynamic information for cemented carbides has been developed. A full description of the alloy system C-Co-N-Nb-Ta-Ti-W is presented. The work has involved both thermodynamic evaluations of lower order systems and experimental investigations. Full new assessments of the quaternary Ti-W-C-N, Ta-W-C-N, and Nb-W-C-N systems have been performed, including tests of the influence of model parameters on miscibility gaps in higher order systems. A new improved description of the Co-W-C system based on new experiments is used in the present work. The main results of the experimental work are measurements of the composition of the cubic carbide in selected equilibria; measurements of the temperatures of the liq + fcc + WC + gr. and liq + fcc + WC + M6C equilibria in the Co-W-C and Co-W-X-C (X = Ti, Ta, Nb) systems; and measurements of the solubility of Ti, Ta, and Nb in liquid in multicomponent alloys. The results of the assessments have been implemented into a new database. The database has successfully been used in a parallel project to simulate the formation of gamma -phase free zones in cemented carbides. A few other applications of industrial relevance are presented.
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| 3. |
- Mao, Huahai, et al.
(författare)
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Volumetric properties and phase relations of silica - thermodynamic assessment
- 2001
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Ingår i: Journal of Alloys and Compounds. - 0925-8388 .- 1873-4669. ; 327:1-2, s. 253-262
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Tidskriftsartikel (refereegranskat)abstract
- Taking into account various available experimental data, an improved internally consistent data set for the SiO2 system is obtained by thermodynamic assessment. The volumetric properties for SiO2 polymorphs are reassessed using the CALPHAD method. A two-coefficient expression is used to describe the thermal expansion and bulk modulus. For liquid phase, one equation is achieved in the temperature range of 298-4000 K either for thermal expansion or for bulk modulus. Phase diagrams have been calculated up to 40 GPa. It has been concluded that, in the pressure range lower than 20 GPa, there is no significant difference between the phase diagrams calculated by the Birch-Murnaghan equation of state (EOS) and by Murnaghan EOS.
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| 4. |
- Ohnuma, I., et al.
(författare)
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Phase equilibria in the Fe-Co binary system
- 2002
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Ingår i: Acta Materialia. - 1359-6454 .- 1873-2453. ; 50:2, s. 379-393
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Tidskriftsartikel (refereegranskat)abstract
- alpha (A2)/gamma (A1) phase equilibria of the Fe-Co system between 400 and 800degreesC were determined by means of lattice parameter measurement using thin film specimens. Bulk specimens were also analyzed to compare the extent of attainment to the equilibrium. The thin film technique was found to be greatly advantageous for obtaining the phase equilibria at lower temperatures where solid-state reactions are too slow to reach the equilibrium state in the conventional methods using bulk specimens. It was confirmed that the alpha + gamma two-phase region extends below the temperature at which the alpha (A2)/alpha' (B2) transus meets the alpha/alpha + gamma boundary. Thermodynamic analysis was also conducted by taking the magnetic and chemical ordering contributions of the B2 structure into account, findings of which confirmed the extension of the alpha + gamma two-phase region below the alpha/alpha' ordering temperature.
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| 5. |
- Sundman, Bo, et al.
(författare)
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Contributions to the thermodynamic modelling of solutions
- 2001
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Ingår i: Zeitschrift für Metallkunde. - 0044-3093. ; 92:6, s. 526-532
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Tidskriftsartikel (refereegranskat)abstract
- The discussion on thermodynamic modelling of solution that started at the Ringberg meeting 1996 is continued with some revisions and some details. In particular the methods to implement chemical ordering for a multicomponent system, also on interstital sublattices and the contributions due to strain energies are discussed.
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| 6. |
- Sundman, I, et al.
(författare)
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Increased [3H]tiagabine binding to GAT-1 in the cingulate cortex in schizophrenia
- 2002
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Ingår i: Neuropsychobiology. - : S. Karger AG. - 0302-282X .- 1423-0224. ; 45:1
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Tidskriftsartikel (refereegranskat)abstract
- Postmortem samples from individuals with schizophrenia (n = 13) and control subjects (n = 10) were investigated for binding of [3H]tiagabine to GABA transporter-1 GAT-1. The binding was analyzed in the cingulate cortex and the caudate nucleus. There were no differences in binding affinity between the groups in any of the investigated areas. The maximum number of binding sites (Bmax) was elevated in the schizophrenic cingulate cortex compared to controls (1,264 ▒ 96 vs. 860 ▒ 123 fmol/mg of protein). The Bmax in the caudate nucleus for schizophrenics (426 ▒ 40 fmol/mg of protein) was the same as for controls (495 ▒ 69 fmol/mg of protein). The increase in GAT-1 in schizophrenia could be explained by a modulatory upregulation in the cingulate cortex. Copyright ⌐ 2002 S. Karger AG, Basel.
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| 7. |
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