The Experts below are selected from a list of 63 Experts worldwide ranked by ideXlab platform

Murat S Unlu - One of the best experts on this subject based on the ideXlab platform.

  • flame retardant effect of boron compounds on red phosphorus containing epoxy resins
    Polymer Degradation and Stability, 2014
    Co-Authors: Mehmet Dogan, Murat S Unlu
    Abstract:

    Abstract The effect of zinc borate (ZnB), Boric acid (BA) and Boric Oxide (b2o3) was studied on the flame retardant and thermal stability properties of epoxy resin containing red phosphorus (RP). The flame retardancy of epoxy based composites was investigated using limiting oxygen index (LOI), UL-94 standard, thermogravimetric analysis (TGA), mass loss calorimeter, scanning electron microscopy (SEM) and attenuated total reflectance – fourier-transform infrared spectroscopy (ATR-FTIR). The addition of 15 wt% RP based flame retardant additive increased the LOI value from 19.5 to 32.5 and V0 rating was obtained from UL-94 test. According to flammability properties, the maximum adjuvant effect was observed at ratio of 9:1 (RP:boron compounds) with the addition of ZnB and BA and at a ratio of 7:3 with the addition of b2o3. With the partial substitution of boron compounds for RP, lower heat release rate (HRR) and total heat evolved (THE) was obtained. According to fire performances, ZnB containing composite showed lowest HRR and THE values. The boron compounds showed beneficial effect by increasing char yield in the condensed phase.

Klaus Betzler - One of the best experts on this subject based on the ideXlab platform.

  • Luminescence of erbium-doped bismuth borate glasses
    Optical Materials, 2006
    Co-Authors: Isabella-ioana Oprea, H. Hesse, Klaus Betzler
    Abstract:

    Abstract Absorption and luminescence properties of erbium ions in the binary glass system bismuth Oxide (Bi2O3)–Boric Oxide (b2o3) are measured for the composition range 25–65 mol% Bi2O3. A Judd–Ofelt analysis of the typical erbium bands in the absorption spectra reveals comparably high Judd–Ofelt coefficients. This indicates a substantial mixing of other electronic configuration into the 4fN configuration by the random crystal fields in the glasses. All coefficients are decreasing with increasing Bi2O3 content, this effect being most pronounced with Ω2. Luminescence decay times and radiative efficiencies show an expressed dependence on the glass composition. Radiative efficiencies of all luminescence bands increase with increasing Bi2O3 content—accompanied, however, by a slight narrowing of the bands. Except the common luminescence bands of erbium, upconversion luminescence at a wavelength of 0.54 μm could be detected.

  • Optical properties of bismuth borate glasses
    Optical Materials, 2004
    Co-Authors: Isabella-ioana Oprea, H. Hesse, Klaus Betzler
    Abstract:

    Abstract Optical properties of glasses in the binary system bismuth Oxide (Bi2O3)–Boric Oxide (b2o3) are measured for the composition range 25–65 mol% Bi2O3. Both, refractive indices and ultraviolet absorption edge, show an expressed dependence on composition. A generalized Sellmeier formula is derived to describe the refractive indices for the whole composition range and a wide wavelength range.

Mehmet Dogan - One of the best experts on this subject based on the ideXlab platform.

  • flame retardant effect of boron compounds on red phosphorus containing epoxy resins
    Polymer Degradation and Stability, 2014
    Co-Authors: Mehmet Dogan, Murat S Unlu
    Abstract:

    Abstract The effect of zinc borate (ZnB), Boric acid (BA) and Boric Oxide (b2o3) was studied on the flame retardant and thermal stability properties of epoxy resin containing red phosphorus (RP). The flame retardancy of epoxy based composites was investigated using limiting oxygen index (LOI), UL-94 standard, thermogravimetric analysis (TGA), mass loss calorimeter, scanning electron microscopy (SEM) and attenuated total reflectance – fourier-transform infrared spectroscopy (ATR-FTIR). The addition of 15 wt% RP based flame retardant additive increased the LOI value from 19.5 to 32.5 and V0 rating was obtained from UL-94 test. According to flammability properties, the maximum adjuvant effect was observed at ratio of 9:1 (RP:boron compounds) with the addition of ZnB and BA and at a ratio of 7:3 with the addition of b2o3. With the partial substitution of boron compounds for RP, lower heat release rate (HRR) and total heat evolved (THE) was obtained. According to fire performances, ZnB containing composite showed lowest HRR and THE values. The boron compounds showed beneficial effect by increasing char yield in the condensed phase.

Isabella-ioana Oprea - One of the best experts on this subject based on the ideXlab platform.

  • Luminescence of erbium-doped bismuth borate glasses
    Optical Materials, 2006
    Co-Authors: Isabella-ioana Oprea, H. Hesse, Klaus Betzler
    Abstract:

    Abstract Absorption and luminescence properties of erbium ions in the binary glass system bismuth Oxide (Bi2O3)–Boric Oxide (b2o3) are measured for the composition range 25–65 mol% Bi2O3. A Judd–Ofelt analysis of the typical erbium bands in the absorption spectra reveals comparably high Judd–Ofelt coefficients. This indicates a substantial mixing of other electronic configuration into the 4fN configuration by the random crystal fields in the glasses. All coefficients are decreasing with increasing Bi2O3 content, this effect being most pronounced with Ω2. Luminescence decay times and radiative efficiencies show an expressed dependence on the glass composition. Radiative efficiencies of all luminescence bands increase with increasing Bi2O3 content—accompanied, however, by a slight narrowing of the bands. Except the common luminescence bands of erbium, upconversion luminescence at a wavelength of 0.54 μm could be detected.

  • Optical properties of bismuth borate glasses
    Optical Materials, 2004
    Co-Authors: Isabella-ioana Oprea, H. Hesse, Klaus Betzler
    Abstract:

    Abstract Optical properties of glasses in the binary system bismuth Oxide (Bi2O3)–Boric Oxide (b2o3) are measured for the composition range 25–65 mol% Bi2O3. Both, refractive indices and ultraviolet absorption edge, show an expressed dependence on composition. A generalized Sellmeier formula is derived to describe the refractive indices for the whole composition range and a wide wavelength range.

Soumia Zaiou - One of the best experts on this subject based on the ideXlab platform.

  • Preparation and characterization of new dental porcelains, using K-feldspar and quartz raw materials. Effect of b2o3 additions on sintering and mechanical properties.
    Materials science & engineering. C Materials for biological applications, 2016
    Co-Authors: Abdelhamid Harabi, Fatiha Guerfa, Esma Harabi, Mohamed-tayeb Benhassine, Lazhar Foughali, Soumia Zaiou
    Abstract:

    The aim of this work was to determine the effect of temperature and Boric Oxide (b2o3) addition on sintering and mechanical properties of a newly developed dental porcelain (DP) prepared from local Algerian raw materials. Based on a preliminary work, the new selected composition was 75wt.% feldspar, 20wt.% quartz and 5wt.% kaolin. It was prepared by sintering the mixture at different temperatures (1100-1250°C). The optimum sintering conditions gave a relatively higher density (2.47g/cm(3)) and excellent mechanical properties. The three point flexural strength (3PFS) and Martens micro-hardness of dental porcelains were 149MPa and 2600MPa, respectively. This obtained 3PFS value is more than four times greater than that of hydroxyapatite (HA) value (about 37MPa) sintered under the same conditions. However, the sintering temperature was lowered by about 25 and 50°C for 3 and 5wt.% b2o3 additions, respectively. But, it did not improve furthermore the samples density and their mechanical properties. It has also been found that b2o3 additions provoke a glass matrix composition variation which delays the leucite formation during sintering.