Yu L.,Refractories Research Co.
Advanced Materials Research | Year: 2010
It is necessary to know the synthesis mechanism of Fe-Si3N 4 by flash-combusting FeSi75 in order to control the phase composition and microstructure of Fe-Si3N4 composites. In this paper, Fe-Si3N4 and starting material FeSi75 were analyzed with XRD, SEM and EDS. The results show that Fe-Si3N 4 synthesized by flash-combusting FeSi75 (≤0.074 mm) is composed of β-Si3N4, α-Si3N4, FexSi, and SiO2, in which β-Si3N 4 and α-Si3N4 are from the nitridation of metal silicon and part of the silicon in ξ phase while FexSi is from the nitridation of ξ phase; during the nitridation of ξ phase, Si content declines gradually, when Fe: Si is close to 3, the nitriding reaction tends to balance; the loose accumulation of nitriding products results in the slow heat release, which makes α-Si3N4 transform to β-Si3N4 and β-Si3N4 grow further to form rod-like β-Si3N4 crystals of high slenderness ratios; the rapid quenching of nitriding products helps to keep the proportion between α-Si3N4 and β-Si 3N4 small particles, and to reduce the crystallization of rod-like β-Si3N4; The grain size and distribution of FexSi in Fe-Si3N4 are related to the particle size and distribution of ξ phase in the starting material.© (2010) Trans Tech Publications.
Yuan B.,Refractories Research Co. |
Ding S.,Saint - Gobain |
Wang D.,Refractories Research Co. |
Wang G.,Refractories Research Co. |
Li H.,Refractories Research Co.
Materials Letters | Year: 2012
Silica aerogel/glass fiber composites were fabricated by press forming of silica aerogel powders and dispersed glass fibers. Due to the nano porous structure, silica aerogel showed low gas thermal conductivity and solid thermal conductivity. By adding the glass fibers, the strength of the composites was improved but the heat insulation property was deteriorated. The thermal conductivities of the composites with 20 wt.% glass fibers at 300 °C and 600 °C were 0.025 W/(m K) and 0.030 W/(m K), respectively. As opacifier, the addition of TiO 2 decreased the radiative thermal conductivity abruptly, especially at high temperatures. At 700 °C, it decreased from 0.041 W/(m K) to 0.030 W/(m K) after 20 wt.% TiO 2 powders were added. © 2012 Elsevier B.V. All rights reserved.
Wang X.,Refractories Research Co
China's Refractories | Year: 2015
The preparation of reference samples for refractoriness under load (non-differential, with rising temperature) of refractories was discussed. According to features and application of reference samples, quartz glass was chosen as a stand-by reference material for uniformity and stability tests. Then, the true value was fixed by gathering the testing results from many labs with stable testing levels and reliable testing results in China. The testing results from these labs were used for normality test by Shapiro-wilk method, and for abnormality value test by Grubbs method-, for equal observation test by Cochran method. After confirming no abnormality values among the testing results from the labs, the average values of reference samples were calculated and the uncertainty was appraised. The results show that the standard value of reference samples is 1 386 °C and the expanded uncertainty is 12 °C.
Li Z.,Refractories Research Co.
Naihuo Cailiao/Refractories | Year: 2010
Effects of dispersing agents in refractory castables and their mechanisms and the different dispersing mechanisms of organic and inorganic dispersing agents were briefly introduced. The development, chemical structural formulas, properties and performances of organic dispersing agents were emphasized. The developing trend of dispersing agents for refractory castables was also pointed out.
Yin H.,Refractories Research Co. |
Zhu D.,Refractories Research Co. |
Hu P.,Refractories Research Co.
Naihuo Cailiao/Refractories | Year: 2010
Corroded high chrome bricks (Cr 2O 3-Al 2O 3-ZrO 2) were investigated by SEM and EDS. Because different compositions of coal slag lead to different m(CaO)/m(SiO 2) of penetration layer, two types of corrosion behaviors appear:(1)there are partial de-zirconium layer, regenerated m-ZrO 2 layer,regenerated m-ZrO 2 and zircon layer, and zircon layer; (2)there are partial de-zirconium layer and penetration layer containing m-ZrO 2. When m(CaO)/m(SiO 2) <0.22, SiO 2 reacts with m-ZrO 2 in the high chrome brick forming zircon layer firstly, with m(CaO)/m(SiO 2) value increasing, m-ZrO 2 and zircon layer, regenerated m-ZrO 2 layer and partial de-zirconium layer form; when m(CaO)/m(SiO 2) >0.27, partial de-zirconium layer and penetration layer containing m-ZrO 2 form.