Showing papers by "Jiaxiang Liu published in 2020"

Hydration Activity and Expansibility Model for the RO Phase in Steel Slag

Abstract: The low hydration activity and volumetric instability of steel slag (SS) limits its application as a binding material. SS contains approximately 30 pct of a divalent metal oxide solid solution (RO phase). According to the XRD results of the RO phase extracted from SS, RO phases (MgO·xFeO) with different compositions were synthesized to study their hydration activity and expansibility. The hydration activity of the RO phase was found to exponentially decrease with the increasing molar ratio (x) of FeO to MgO in the RO phase. When x ≥ 1 .5, the RO phase could not be hydrated after autoclaving at 215 °C and 2 MPa for 3 hours. The RO phase was blended into cement to study the relationships among the expansibility and composition and content of the RO phase via an autoclave test. When x ≤0.5, more than 5 pct of the RO phase cracked the specimen. When 0.5 < x < 1.5, the autoclave expansion rate of the specimen decreased with the increasing value of x in the RO phase. When x ≥ 1.5, the autoclave expansion rate of the specimen linearly increased with the content of the RO phase and was independent of the composition of the RO phase.

Study on the application mechanism and mechanics of steel slag in composite cementitious materials

Abstract: Enormous demand and production for cement and concrete lead to a sharp increase in carbon dioxide emissions, and alternatives to cement are urgently needed to produce green cement and concrete. This paper is aimed at exploring the feasibility of using steel slag (SS) and granulated blast furnace slag (GBFS) to prepare cementitious materials. Mineral phases of SS are determined and observed by X-ray diffraction and backscattered electron microscopy. By measuring the compressive strength of mortar samples, the composite effect of SS-GBFS is analyzed and compared. Results show that SS can replace cement by 10%–30%, and the long-term strength of the prepared binary cementitious material is higher than that of cement. SS and GBFS can replace up to 50% of the cement. The strength of SS-GBFA-C ternary cementitious material is higher than that of SS-C, SS and GBFS promote mutually in cementitious materials.

Synthesis of hexagonal-phase indium tin oxide nanoparticles by deionized water and glycerol binary solvothermal method and their resistivity

Abstract: Hexagonal-phase indium tin oxide nanoparticle (h-ITO NP) is a high-temperature and high-pressure phase, and its preparation is more difficult than the cubic one. In this work, low-resistivity and single hexagonal-phase ITO NPs were synthesized through a binary solvothermal method of deionized water (DI water) and glycerol (GL) at relatively mild conditions combined with post-heat treatment. The effects of experimental parameters such as the volume ratios of DI water and GL, reaction time and temperature on the phase, morphology as well as electrical resistivity of h-ITO NPs were explored systematically. The results showed that the reaction time can be as short as 30 min when the single hexagonal-phase ITO NPs were synthesized at 200 °C. And the h-ITO NPs can also be synthesized when the temperature was as low as 110 °C by an 8-h reaction. The lowest resistivity of 1.258 Ω cm can be reached when the volume ratio of DI water to GL was 1:1, the reaction temperature and time were 200 °C and 8 h, respectively. Moreover, the mechanism of the influence of experimental conditions on the resistivity of ITO NPs was also analyzed.

Preparation of modified silicon carbide powder with high dispersibility for slip casting

Abstract: Silicon carbide (SiC) powder was modified with γ-mercaptopropyl trimethoxysilane (KH590) and tetramethylammonium hydroxide (TMAH). The effects of modification were investigated following viscosity ...

Effect of Particle Size on Target Sintering Behavior of Cubic ITO Nanopowders

Abstract: The effect of particle size on the density and resistivity of ITO green bodies and targets was systematically investigated. The experimental results show that the relative density of ITO green bodies decreases with the increase of ITO particle size. When the particle size is 10.7 nm, the relative density of ITO green bodies rises to the maximum value of 56.6%. The resistivity declines exponentially with the increase of particle size, which satisfies the exponential equation of R = exp(−41.823 × d). When the particle size is 41.6 nm, the resistivity reaches the minimum value of 0.8 Ω·cm. The relative density of ITO target decreases with the increase of particle size. Fine particles can increase the driving force of densification in initial stage. Electron mobility, caused by grain boundary scattering, will increase due to the increase of particle size or the decrease of grain boundary potential. When the particle size is 10.7 nm, the target with compact grain stacking and low porosity shows a maximum relative density of 99.25%, and the resistivity reaches the minimum value of 0.34×10−3 Ω·cm.