Abstract: The introduction of carbon greatly improves the high temperature performance of magnesia bricks. In order to explore the influence of carbon content on the fracture toughness and the fracture mechanism of magnesia-carbon bricks, two different carbon content (10wt% and 14wt%) magnesia-carbon bricks were investigated in this work. The fracture toughness and microstructure were characterized by fractal analysis of fracture surface and scanning electron microscope respectively. The results indicated that the strength of magnesia-carbon bricks was strengthened with the carbon content increasing. It was demonstrated that magnesia-carbon bricks with the higher carbon content presented higher fracture toughness as a consequence of lower apparent porosity and compact bonding between matrix and magnesia aggregates.
Abstract: The spherical indentation combined with acoustic emission was used to evaluate the local strength of glass, which is a nondestructive testing approach. However, stress time effect on the local strength of glass during spherical indentation has not been studied before. In the present work, stress time effect was investigated by examining the local strength of unstrengthened and strengthened glass at different loading rates. It is discovered that the local strength of glass increased greatly with the loading rate, which confirmed the time dependence of the fracture on glass. As a typical brittle material, the discreteness of strength date of glass measured by spherical indentation was also analyzed to evaluate the strength of glass correctly.
Abstract: Tensile bond strength is one of the most significant properties for structural silicone sealants used in the glass curtain walls. During the service process, aging of the silicone sealants shall be involved in comprehensive actions of environment factors, e.g. temperature, humidity, and ultraviolet light etc. In this study, artificial accelerated aging test was conducted to make clear the development of tensile bond strength, Shore hardness and elongation. The test results show that: (i) the specimens under damp-heat test have more degeneration than specimens under humidity-freeze test; (ii) the environment of high temperature and high humidity leads to the change of tensile bond, Shore hardness, elongation, and results in interfacial failure of samples.
Abstract: The residual stress on the surface of tempered glass is very important for its safe service and the quality control. In this study, the sphere indentation and grazing angle surface polarimetry are compared to evaluate the surface residual stress of tempered glass. The test results showed that the measured results are similar, but the data dispersion of the sphere indentation method is little larger. The main reason is stemmed from the different tested area, of which residual stress is a mean value measured by the grazing angle polarization method. Yet for the indentation method, the residual stress in the micro region of glass is more susceptible to the inhomogeneity of material itself. However, it is difficult to select the right multiple optical path difference for the grazing angle polarization method, and it is only applicable when inspecting the tin surface of tempered glass, as well as the tin surface examination instrument. Thus, as a nondestructive testing method, indentation method can be widely used to measure the surface residual stress of glass without being influenced by other factors.
Abstract: Alumina ceramics are widely used in the demanding high temperature applications in which the high temperature elastic moduli (EHT) is a key property for their reliability and safety. In this paper, the elastic modulus of alumina was determined by dynamic method (impulse excitation technique) and static tests (three-point bending test and four-point bending test). For the static tests, the relative method was applied to determine the accurate deflection measurement in the heating furnace. The measured results revealed that the modulus of alumina slowly decreased from RT to 1000 °C and rapidly decreased with the increasing temperatures from 1000 °C to 1300°C. The EHT evaluated by dynamic method were higher than that tested by static tests with the reason of that impulse excitation technique only applied small forces onto a sample such that defects activity is negligible. Also the resonant frequencies couldn’t be measured easily at high temperature, because the vibration signal emitted by the sample was weak. The static approaches combined with relative method were beyond the limit to high temperatures, and they can be also used to evaluate the ultra-high temperature modulus.
Abstract: With reference to the international standard ISO16000-9 and the national standard GB/T 31106-14, this paper has chosen leather seats as the research object in order to study the emission of volatile organic compounds (VOCs) and total volatile organic compound (TVOC). The test results show that about 21 species of VOCs released from the leather seats were measured, including several types of aldehydes, ketones, aromatic hydrocarbon ,hydrocarbon, lipids and so on.This paper analysis the possible sources of volatile organic compounds in leather seats as well.
Abstract: The method of X-ray fluorescence spectrometry (XRF) for the determination of MgO in magnesia refractories was introduced. The uncertainty of the MgO in refractory materials was analyzed by melting method of XRF. The measurement uncertainty was evaluated, and the related mathematical models was established. The uncertainty of synthetic standard was calculated by the evaluation of the uncertainty of each component standard. And eventually converted to the measurement results to expand the uncertainty. The effects of two melting methods on the uncertainty of magnesium oxide content were compared.
Abstract: A fast and accurate method for simultaneous determination of the content of fluorine and chlorine in inorganic thermal insulation materials by ion chromatography was developed. The samples were cut into pieces of weight less than 40mg, washed with water as the extractant, heated for 30 min and then centrifuged, filtered through a 0.22 μm microporous membrane, and the cation was removed using a SEP-H column. The solution was rinsed with 20/30 mM KOH as the mobile phase, separated by anion exchange column and then detected using a conductivity detector. The mass concentration of fluorine and chlorine in the range of 0.1-10mg/L was linearly related to their peak area, the detection limit of fluorine was 0.030mg/Land the detection limit of chlorine was 0.016mg/L. The relative standard deviations (n=6) of the three typical inorganic insulating materials (glass wool, rock wool and mineral wool) were less than 2.0% and the rate of recovery of fluoride and chloride ion was between 97% and 101%.The method had good accuracy and recovery rate. The absolute error of the measured value between ion chromatography and the national standard was less than 0.20%.The results showed that the method was suitable for the determination of the content of fluorine and chlorine in inorganic thermal insulation materials
Abstract: In this paper, we take Zr Kα line as the analysis object due to the existence of overlapping phenomenon, which the zirconium La line (0.607nm) and phosphorus Ka line (0.615nm), in phosphorus-containing zircon-refractory material. We discovered and calculated the critical thickness of glass fuse by the theoretical calculation method, and we verified the feasibility of the theory. By experiment we found that critical thickness of glass fuse can be reduced by adding additives in flux. Conventional thickness of glass fuse can reaches a critical thickness by adding 20% of calcium oxide (in the form of calcium carbonate was added) in flux. This method could also increase significantly the measurement sensitivity to guarantee good result.