| 11. |
- Aune, Ragnhild E., et al.
(författare)
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Thermophysical properties of IN738lc, MM247lc and CMSX-4 in the liquid and high temperature solid phase
- 2005
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Ingår i: Superalloys 718, 625, 706 and Derivatives, Proceedings. - : TMS. ; , s. 467-476
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Konferensbidrag (refereegranskat)abstract
- Thermophysical properties of the Ni-based superalloys CMSX-4, IN738LC, and MM247LC have been measured in the liquid and high-temperature solid phase. Properties included calorimetric, thermal transport, the surface tension, and the viscosity. Experiments have been performed in ground-based laboratory using classical calorimetry and rheometry as well as under reduced gravity conditions in an electromagnetic levitation device on board parabolic flights. In this contribution, an overview of the various properties of three Ni-based superalloys is given with emphasis on the surface tension and viscosity as obtained from the parabolic flight experiments. The measurements were performed within a program called ThermoLab dedicated to the measurement of thermophysical properties of industrial alloys.
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| 12. |
- Backman, Sara, et al.
(författare)
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Material Wear of Polymeric Tracheostomy Tubes : A Six-Month Study
- 2009
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Ingår i: The Laryngoscope. - : Wiley. - 0023-852X .- 1531-4995. ; 119:4, s. 657-664
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The objectives were to study long-term material wear of tracheostomy tubes made of silicone (Si), polyvinyl chloride (PVC), and polyurethane (PU) after 3 and 6 months of clinical use. Study Design: The study has a prospective and comparative design. Methods: Nineteen patients with long-term tracheostomy, attending the National Respiratory Center in Sweden, were included, n = 6 with Si tubes, n = 8 with PVC tubes, and n = 5 with PU tubes. The tubes were exposed to the local environment, in the trachea for 3 and 6 months and analyzed by scanning electron microscopy, attenuated total reflectance Fourier transform infrared spectroscopy, and differential scanning calorimetry. Results: All tubes revealed severe surface changes. No significant differences were established after 3 or 6 months of exposure between the various materials. The changes had progressed significantly after this period, compared to previously reported changes after 30 days of exposure. The results from all analyzing techniques correlated well. Conclusions: All tubes, exposed in the trachea for 3-6 months, revealed major degradation and changes in the surface of the material. Polymeric tracheostomy tubes should be changed before the end of 3 months of clinical use.
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| 13. |
- Björling, Gunilla, Docent, et al.
(författare)
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Clinical use and material wear of polymeric tracheostomy tubes
- 2007
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Ingår i: The Laryngoscope. - : Lippincott Williams & Wilkins. - 0023-852X .- 1531-4995. ; 117:9, s. 1552-1559
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: The objectives were to compare the duration of use of polymeric tracheostomy tubes, i.e., silicone (Si), polyvinyl chloride (PVC), and polyurethane (PU), and to determine whether surface changes in the materials could be observed after 30 days of patient use. METHODS: Data were collected from patient and technical records for all tracheostomized patients attending the National Respiratory Center in Sweden. In the surface study, 19 patients with long-term tracheostomy were included: six with Bivona TTS Si tubes, eight with Shiley PVC tubes, and five with Trachoe Twist PU tubes. All tubes were exposed in the trachea for 30 days before being analyzed by scanning electron microscopy (SEM) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). New tubes and tubes exposed in phosphate-buffered saline were used as reference. RESULTS: Si tubes are used for longer periods of time than those made of PVC (P < .0001) and PU (P = .021). In general, all polymeric tubes were used longer than the recommended 30-day period. Eighteen of the 19 tubes exposed in patients demonstrated, in one or more areas of the tube, evident surface changes. The morphologic changes identified by SEM correlate well with the results obtained by ATR-FTIR. CONCLUSIONS: Si tracheostomy tubes are in general used longer than those made of PVC and PU. Most of the tubes exposed in the trachea for 30 days suffered evident surface changes, with degradation of the polymeric chains as a result.
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| 14. |
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| 15. |
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| 16. |
- Morales, R., et al.
(författare)
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Hydrogen reduction of complex oxides - a novel route toward the production of nanograined alloys and intermetallics
- 2005
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Ingår i: Scandinavian journal of metallurgy. - : Wiley. - 0371-0459 .- 1600-0692. ; 34:2, s. 108-115
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Tidskriftsartikel (refereegranskat)abstract
- One of the major obstacles in the incorporation of nanomaterials in high technology is the lack of new processes for the bulk production of the materials with compositions tailored to suit the application. Oxides can potentially be reduced to metals, intermetallics or alloys by hydrogen or natural gas. The formation of homogeneous alloys and intermetallics by this method has been confirmed by a number of experimental studies. The kinetics of hydrogen reduction of pure oxides of transition metals as well as complex tungstates, molybdates, titanates, aluminates and chromate were investigated by thermogravimetry. The formation of homogeneous alloys and intermetallics was confirmed by these studies. Arrhenius activation energies of the reduction reactions could be linked to the stabilities of the complex oxides. The products were found to have nanograin structure. Bulk processing through hydrogen reduction route was examined in the case of iron molybdate using a fluidized bed reactor.
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| 17. |
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| 18. |
- Roseborough, Diana, et al.
(författare)
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The surface behavior of mercury on iron systems
- 2006
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Ingår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science. - 1073-5615 .- 1543-1916. ; 37:6, s. 1049-1056
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Tidskriftsartikel (refereegranskat)abstract
- Thermal desorption Auger electron spectroscopy (TDAES) was used to investigate the circumstances under which mercury is adsorbed on the surface of iron in the temperature interval of 85 to 298 K. The effects of chlorine and oxygen modifications on the iron surface have also been investigated within the same temperature interval. It was seen that chlorine reduced the adsorption of mercury on polycrystalline iron at 85 K, as did oxygen. On the clean iron system at 298 K, only one monolayer (ML) of mercury adsorbed. The physisorption of mercury on chlorine and oxygen layers at low temperatures (LTs) is discussed in combination with the calculated activation energies of desorption, as well as the factors affecting the mechanism of adsorption at room temperature.
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| 19. |
- Sterneland, Therese, et al.
(författare)
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Investigation of (Cr,Co)(7)C-3-fcc-graphite equilibrium in the temperature interval 1373 to 1473 K
- 2006
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Ingår i: Metallurgical and Materials Transactions. A. - : Springer Science and Business Media LLC. - 1073-5623 .- 1543-1940. ; 37A:10, s. 3023-3028
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Tidskriftsartikel (refereegranskat)abstract
- In the current study, the phase equilibria between fee, graphite and M7C3 (M = Cr,Co) have been studied at 1373 degrees K, 1423 degrees K, and 1473 degrees K. The solubility of Co in the M7C3 phase and the solubility of Cr and C in the fee phase have been determined by the high-temperature equilibration and quenching technique. Appropriate mixtures of Cr7C3 + Co or Cr7C3 + Co + C were equilibrated and subsequently quenched in liquid nitrogen. The quenched samples were characterized by X-ray diffraction and by metallographic examination. The studies were carried out on the samples to determine the homogeneity of the sample as well as the phases and their composition. From the results, the compositional regions of the three-phase triangle M7C3 + fee + graphite could be accurately determined. The results show that the Co solubility in the Cr7C3 in the experimental temperature interval is higher than previous investigations performed at higher temperatures.
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| 20. |
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