Key Engineering Materials Vol. 633

Abstract: Grounding net is necessary to ensure the security of electrical equipment and personal safety for the high voltage transmission tower. The grounding resistance under power frequency of the grounding net must meet the national standard. The normal resistance-reducing agents show conductivity instability, short service life and poor water-retaining property. The conductive concrete is capable of good permeability, water-retaining property and conductivity. While there is an contradiction between the high mechanical strength and good conductivity. In this paper, the acrylic acid emulsion is used to increase the adhesion stress between the steel fibers and the concrete.

Abstract: This paper studies the influence law of experiment time, load level under sustained pressure load and the corrosion environment interaction on the permeability of chloride ion in concrete,which is through natural diffusion method. Experimental results show that with the increase of the test time, the penetration depth of chloride ions in concrete and the content of chloride ions in the same penetration depth is growing. As the load level increases, there is a tendency of the chloride ion content after the first increase and then decrease, the turning point in the middle remains to be studied. The research results have a certain significance for concrete durability design and life prediction in corrosion environment.

Abstract: According to analyze service condition and extent of damage of cordierite bricks used in coke oven, the experiment was prepared by using spodumene powder, cordierite powder and fused silica as main starting materials, borax as the flux. The effect of borax on melting properties and thermal shock resistance of low-temperature glaze used in coke oven cordierite brick was investigated. The results showed that the melting temperature of glaze is close to the theoretical calculation, Seger formula can be equally applied to metallurgical industry. With the amount of borax increasing, the melting temperature of the glaze reduced. When the amount increased to 22%, borax dissolved in the mullite phase, which increased the content of glass phase in glaze. When the temperature is 1000°C, glaze layer formed and spreaded evenly on the surface of cordierite lining bricks and didn’t flowing. After five thermal shock, glazed surface didn’t appear crack, the requirements were achieved that glaze can be generated in the carbonization chamber temperature of coke oven without pre-firing. When the amount of borax continues to increase, the viscosity of glaze decreases, which results in flowing.

Abstract: A new immobilization technique that encapsulates B. pasteurii in the fine waste cement mortar particles (FWM) was being investigated to induce CaCO₃ precipitation in reducing porosity and refining pore size of old cement mortar (OCM), where FWM particles were crushed from old cement concrete and passed through a size of 5 mm sieve. The capillary water absorption test (CWA) and scanning electron microscopy (SEM) were carried out to evaluate the pore-refining effect of this bio-treated methods. X-ray diffraction analysis (XRD) was used to analyze the morphology and the composition of the treated OCM. The results showed that a larger quantity of calcium carbonate bio-depositions were formed and filled the pores of OCM. As a result, the capillary water absorption was decreased by 47% compared with untreated-OCM, respectively.

Abstract: Disordered application of bentonite in the waterproof projects has caused irreparable damage to the economic and environmental for the shortage of significant identification methods of natural sodium bentonite. Considering the complex domestic situation of bentonite using, 3 types of natural sodium bentonite and 6 types of bentonite materials in geosynthetic clay liner (GCL) in the market were studied and compared in this research to address means for identification and assessment of natural sodium bentonite. Against the potential modification of bentonite, various ways of characterization were applied in this study, including fluorescence analysis, X-ray- diffraction (XRD), and fourier transform infrared spectroscopy (FTIR), as well as the tests of retention rate of swelling index, Na⁺, K⁺ and Ca²⁺, Mg²⁺ ion content measurement, pH value, DSC, anion measurement, et.al. It was found that a series of parameters and corresponding indicators, which were confirmed to discriminate the applied modification means on the bentonite, could be used for the identification and assessment of natural sodium bentonite by mutual testifying the different parameters.

Abstract: The green Hetian nephrite, which has delicate textures, spinach-like green and less cracks, contains three types of aggregates: primary nephrite, placer nephrite and Gobi nephrite. The deposits were located in the south part of the Tarim Basin, Xinjiang, China. In the orebodies of the deposits, primary nephrites occurr as veins or lenses along faults or fissures of adjacent ultramafic rocks. Samples with fine-grained and felted cohesive textures were collected from Hetian-Yutian County, Xinjiang Uyghur Autonomous Region, its mineralogical characteristics, H-O isotopic characteristics and forming mechanism have been discussed by means of SEM, EPMA, XRD, IR spectrum, Raman spectrum, DTA and TG study, and H-O isotope study. Microscopic observation and SEM show that green nephrite has interlocking-felted cryptocrystalline blastic texture with fine topography and high compactness. Tremolite, as a main mineral composition of the green nephrite, has high amounts of Si, Ca, and Mg; it turns into actinolite with the help of increasingly large amount of Fe. XRD, IR spectrum and Raman spectrum identified the occurrence of accessory minerals of chromite, chlorite, serpentine, clinopyroxene and apatite. DTA study demonstrates that the structure of tremolite was destroyed at 900 – 1100°C, while TG study demonstrates the tremolite has such little water that it lost only 0.89 – 1.33% of its weight when heated to 900 – 1100°C. The petrogenesis of green Hetian nephrite deposits are implied to be a result of metasomatic alteration of ultramafic-mafic rocks, and the black, spot-like chromite implies ultramafic-mafic rocks. The analysis of H-O isotope study indicates that the ore-forming hydrothermal fluids of Gobi nephrites are primary magmatic water, but details of hydrothermal fluids of primary and placer nephrites are still remained unknown and needed to be investigated furthermore.

Abstract: Loess based copolymer (L/CoPolym), a typical silicate minerals / copolymer composite, was used as polymer adsorbent for removing basic fuchsin (BF) in wastewater. Under the optimal condition of adsorption, the removal rate of BF reached to 98.2%, and the adsorption capacity got to 565.0 mg/g. Adsorption dynamics were consistent with pseudo-second-order kinetic model and isotherm model can meet the Freundlich isotherm.

Abstract: It is found that cuprous sulfite, zinc sulfate and zinc sulfide were the main phases of copper and zinc in zinc leach residue, through analyzing its composition and phase characteristics by XRF and XRD. The method that cooperate sulfuric acid leaching with oxidant was chosen. 60 g/L H₂SO₄ at 60 °C for 2 h with 4% KMnO₄ and liquid/solid ratio of 5..1, 84.29 % of Cu and 92.02 % of Zn are extracted. The ion concentration of copper and zinc are tested by UV-VIS spectrophotometer and EDTA titration respectively. The results show that the amount of acid is sufficient for leaching at the condition of 60 g/L H₂SO₄ and liquid/solid ratio of 5..1. At the same time, copper change from low valence into high valence after adding KMnO₄ which strengthen the leaching, and the chemical reaction can reach balance at 60 °C for 2 h. This method has good extraction effect on copper and zinc.

Abstract: This paper used the metallographic analysis, X-ray diffraction analysis (XRD), differential scanning thermal analysis (DSC), scanning electron microscope (SEM) and electron probe analysis (EPMA) system to research the evolution law of the microstructure and properties of AA7050 under different homogenization system. And analyzes the cause of this evolution combined with the test results put forward. The research shows that high melting point eutectic phase S (Al₂CuMg) can be fully re-dissolution through two-stage homogenization, at the same time avoid the overburning of low melting eutectic phase. We optimized the AA7050 homogenization heat treatment system and the optimal homogenization scheme is 430°C/18h+467°C/12h.

Abstract: Using the micron alumina powder for the study, through the analysis of the ceramic suspension rheological, the generation and evolution and its mechanism of aggregates in the ceramic suspension were studied. The results showed that the number, size and intensity of aggregates will be effected by the gravitational potential or the barrier height between the particles in suspension as varying the process conditions. Generally, the formation of aggregates was corresponded to the interaction potential between particles, that is, the second potential well. Thus, their internal bonding strength is weak. In the flowing suspension, aggregates were meta-stability under shear forces, electrostatic repulsion and van der Waals potential. The variation of the aggregates was a reversible process as decomposition then reunion again.