Showing papers by "Swedish Institute published in 1987"

A Thermodynamic Analysis of the Fe-Cr-N System

Abstract: New experimental information on the phase relations in the Fe-Cr-N system at 1273 K is presented. Together with previous information it is used in a thermodynamic analysis of the system in the temperature range from 1273 to 1473 K. A set of parameter values is derived which defines the Gibbs energy of the individual phases and allows the phase diagram to be calculated. Satisfactory agreement with experimental information is obtained.

An experimental and thermodynamic study of the Fe-Cr-C-N system at 1273 K

Abstract: The thermodynamic properties of the Fe-Cr-C-N system at 1273 K (1000 °C) have been evaluated using old and new information. The binary systems are well established. The Fe-Cr-C system is fairly well established, but some experiments were performed in this study in order to establish theα/γ/M23C6 equilibrium. The Fe-Cr-N system was evaluated in a parallel study. In the Fe-C-N system the properties of theα andγ phases are well established. No direct information from the Cr-C-N system was used. In order to establish the properties of the quaternary system some experiments were made by equilibrating a set of Fe-Cr-C-N alloys at 1273 K, using a sealed capsule technique. After quenching, the carbon and nitrogen activities were evaluated by analyzing the specimens, which were completely austenitic. Phase equilibria in other specimens were studied by microprobe measurements and X-ray phase identification. When the quaternary system was evaluated thermodynamically, it was found that all the experimental information could be reasonably well accounted for without introducing new parameters for the quaternary system. However, it was necessary to evaluate the properties of the metastablee-Cr2C phase in order to fit the quaternary experimental information. The phase diagram was calculated from the evaluated thermodynamic properties. A number of sections are presented for direct comparison with the experimental data.

A Study of equilibria in the Fe-Cr-Ni-Mo-C-N system at 1273 K

Abstract: The phase equilibria in the Fe-rich corner of the Fe-Cr-Ni-Mo-C-N system have been studied at 1273 K using a sealed capsule technique to measure the C and N activities and the electron microprobe to measure the compositions of the individual phases following identification by X-ray analysis. Some of the new information was combined with previous assessments of the Fe-Cr-N, Fe-Ni-N, and Fe-Cr-Ni systems and a new assessment of the Cr-Ni-N system in order to assess the thermodynamic properties of the Fe-Cr-Ni-N system. A set of parameters is obtained, based mainly upon experimental information from 1273 K (1000 °C) and 1473 K (1200 °C), which can be used for calculations of the Fe-Cr-Ni-N phase diagram in this temperature range. Isothermal sections are presented and show reasonable agreement with experimental data not used in the assessment. The thermodynamic analysis is restricted to the Fe-Cr-Ni-N system, but some experimental data are also presented for alloys containing Mo and C.

Fine colloidal silica as reinforcing filler in polyurethane polymers

Abstract: Colloidal silica in the particle size range 1.4–10 nm was extracted in to tetrahydrofuran (THF). Alkali silicate solutions with SiO2 : M2O (M = Li, Na, K, Cs) ratios ranging from 3:1 to 20:1 were used as source of silica particles in the size range 1.4–4.4 nm whereas commercial silica sols were used for particles in the range 5–10 nm. Films of polyester- and polyether-based polyurethane-containing colloidal silica were prepared and their mechanical properties measured. The reinforcing effect increased with increasing silica content and showed a maximum between 1.5 and 2.5 nm for polyether-based polyurethane and between 4 and 6 nm for polyester-based polyurethane. The area under the hysteresis loops of the stress–strain curves also showed maximum in the same particle size ranges for the two types of polyurethane. Reinforcement mechanisms are discussed in terms of interactions between small particles and hard or soft segments of the polymer chains.

The Effect of Carbon Content on Recrystallisation and Texture Development in Steel

Abstract: The effect of differential carbon contents on recrystallisation and texture development has been studied using samples designed to have a known concentration profile. Dissolved carbon can play an active role both at the deformation and annealing stages. Textural changes are associated principally with enhancement of the nucleation rate for recrystallisation with increasing carbon contents. The {111} components become weaker and are replaced by widely scattered orientations. Interstitial carbon present during rolling gives rise to shear banding, causing a further increase in nucleation rate during recrystallisation and an associated development of the Goss texture.

Cost-effectiveness of neonatal IgE-screening for atopic allergy before 7 years of age.

Abstract: Obvious atopic diseases developed in 18% of 1651 non-selected children before 7 years of age. More than 80% of newborns with high IgE concentrations in cord blood developed atopic diseases before this age. Although the sensitivity of the IgE test is rather low (40%), most cases (94%) of severe, long-lasting atopic disease show a high neonatal IgE concentration, and the specificity of the test is high (94%). Calculations of total costs of screening were made on the basis of family history alone compared with neonatal IgE-screening in two groups: all newborn infants, or infants with a family history of atopic disease. The cost of preventive measures and treatment costs were included in the calculations. Results were compared with the cost of conventional treatment. Provided that preventive measures delay onset of symptoms in atopic-risk subjects (and assuming total patient compliance) then IgE-screening was cost-effective in both groups, which screening solely on a basis of family history was not. In Sweden there was a total saving of approx. 20 million SEK or 3 million US$ per annum. Thus, IgE-screening of cord blood to select newborns for preventive measures is also economically worthwhile.