Papers by Author: Chang Sen Zhang

Abstract: The accelerated carbonation with different pressure steaming conditions was used to process the steel slag, so the slag could turn into a primary cementitious product with carbonation activity. XRD, FTIR, TG, N₂ absorption BET surface area analyzer and SEM were used to characterize the mineral and chemical compositions and microstructure of each sample before and after the carbonation. The results show that: the carbonation products with different morphologies are formed under different temperature conditions. The optimum temperature for the accelerated carbonation for processing the steel slag is selected to be 90 °C, which results in the compressive strength of 32.8 MPa. The BET specific surface area of the steel slag reduces after carbonation, the sample density increased after carbonation.

Abstract: The La-doped barium ferrites microparticles were successful synthesized by citrate sol-gel method. The structure, morphology and magnetic properties of the ferrite were characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), differential thermal analysis (TG-DSC) and superconducting quantum interference device (SQUID). The results showed that the average crystallite size of La-doped barium-ferrite decreased with increasing La content. The morphology of the barium ferrite was spherical particles; however, doped lanthanum, barium ferrite changed into laminated structure. In addition, doping lanthanum improved the magnetic properties of the ferrite. The saturation magnetization (Ms) of La-doped M-type barium ferrite 67.70emu/g, it was greater than the non-doped M-type barium ferrite 57.45emu/g.

Abstract: The property of raw kaolinite-coal-gangue is very stable, and reactivity of kaolinite-coal-gangue is enhanced by mechanical force. The SEM, XRD and IR were used to analyze mechanochemical changes during kaolinite-type-coal gangue grinding. The results showed that mechanical force plays a dominant role in the enhanced reactivity, by inducing dehydration reactions the lattice OH grouping decreased with the extension of grinding time. The separation of tetrahedral and octahedral layers combined with the increasing disorder of the kaolinite crystal structure, resulting in kaolinite-type-coal gangue particles become "loose" aggregates. Moreover, due to destroy to tight Si-O and Al-O bond, the mechanical force increases the solubility of SiO2 and Al2O3, which enhanced the reactivity of coal gangue.

Abstract: In this paper the waterproofness of desulfurization building gypsum had been improved by polyacrylamide(PAM) emulsion. The effect of dosage and molecular weight of PAM emulsion on the physical mechanical properties and waterproofness have been investigated and XRD, SEM have been employed to determine the phase compositions of the material. The results showed that softening coefficient of desulfurization building gypsum increased from 0.34 to 0.69, the compressive strength after soaking in water for 24 h increased from 4.9MPa to 6.1 MPa. The effect of PAM emulsion modification prepared by PAM with molecular 3 million weight of on desulfurization building gypsum are better than with molecular weight of 5 million. The effect mechanism of PAM on desulfurization building gypsum was that PAM reacts with the Ca2+ cations produced desulfurization building gypsum hydration to form the ionic compounds acting as a filler and reinforcement in the porosity of desulfurization building gypsum, and also PAM covered the surface of desulfurization building gypsum particles to prevent the crystallization of CaSO4.2H2O.

Abstract: Polyaniline (PANI) and polypyrrole (PPy) doping with hydrochloric acid (HCl), p-toluenesulfonate (pTSA) were successfully synthesized by chemical oxidation polymerization. Ammonium peroxydisulfate was used as an oxidizing agent at room temperature. Microstructure of PPy and PANI was studied by scanning electron microscopy (SEM). Discussed the acid concentration how influenced on the electrical conductivity properties of PANI and PPy, and also compared their resistivity and thermal stability. The results showed that HCl effectively improved conductive properties of PANI in a wide range concentrations, and pTSA in narrow range concentrations. When doping with HCl, the minimum volume resistivity of PANI was 0.24 Ω • cm, and PPy was about 10.5 Ω • cm. When doping with pTSA, the volume resistivity minimum of PANI was 1.3 Ω • cm, and PPy was 15.8 Ω • cm. The conductivity of PPy was weaker than PANI. The thermal stability of conducting polymers which doping with pTSA was better than which doping with HCl.

Abstract: Cobalt ferrites were prepared by citrate sol-gel method, chemical co-precipitation, mechanical grinding, respectively. The grain size, morphology, and the size of crystal particles were studied by x-ray diffraction (XRD) and scanning electron microscope (SEM). Cobalt ferrite showed different morphologys when prepared by different methods, It was tapered corners which prepared by sol-gel method; It was tetrahedral which prepared by mechanical grinding method; It was sphere which prepared by chemical co-precipitation method. The average grain size of cobalt ferrite was less than 100nm, while particles prepared by chemical precipitation method were the smallest. The size of Cobalt ferrite prepared by sol-gel method was decreased with the cobalt content increased.