Materials Science Forum Vol. 814

Abstract: Silicon carbide (SiC) reticulated porous ceramics were prepared by organic foam impregnation, using polyurethane sponges as template and deionized water or alcohol as slurry solvent. The sintering behavior, microstructures and apparent density of struct of the SiC reticulated porous ceramics fabricated using the aqueous slurry under different sintering aids and sintering process and the alcohol slurry were investigated comparatively. The experimental results showed that both the microstructures and apparent density of the samples fabricated by Y₂O₃+AlN as sintering aid were better than those Al₂O₃ as sintering aid while the aqueous slurry, and the samples fabricated by two-step process (firstly heated to 700 oC in air furnace, and then sintered at 1800 oC in Ar atmosphere) while Y₂O₃+AlN as sintering aid obtained the optimal properties. In particular, the samples fabricated by the alcohol slurry and reaction sintering process were provided better properties than the aqueous slurry.

Abstract: Granulated blast furnace slag (GBFS) is a by-product of ironmaking and widely used in the cement and concrete. GBFS samples with different ratio of SiO₂/Al₂O₃ were prepared under the laboratory conditions and ground by the agate ball mill at different times. Then they were characterized by laser particle size analysis (LPSA), scanning electron microscopy (SEM), Bertrand surface method and mechanical testing. It was found that the activity index of GBFS clearly increased with the decrease of the GBFS particle size. In the case of the average particle size about 32μm, the activity indices were irregular with the increase of SiO₂/Al₂O₃ ratio, whereas for the average particle size about 11μm, the activity indices decreased with the increase of SiO₂/Al₂O₃ ratio.

Abstract: As a new type of non-metallic mineral resource, serpentine has attracted more and more attentions. Serpentine mineral resources are abundant in China, with more than 5 billion tons reserves proved. However, most of them have not been used adequately except for some special serpentine, such as serpentine jade and chrysotile. The overview for status quo of serpentine utilization consists of the distribution, chemical compositions, crystal structure of serpentine, mature but not economic applications and some development of high-value utilization research. It is expected to provide some references for deeper research and promoting its applications.

Abstract: The TiO₂ complex samples were produced through sol-gel method, using Ti (OC₄H₉)₄, rice husk (RH) and methenamine as the reactants. Some property analyses were conducted, including X-ray diffraction (XRD), Brunauer-Emmet-Teller (BET), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and photocatalytic experiments in the condition of visible-light. The results showed that the size of crystal was limited with the addition of RH in the complex of N/RH/TiO₂ samples. The particles of TiO₂ were dispersed on the surface of rice husk ash, the skeleton of RH after burning. It can inhibit the phenomenon of agglomerate. The ability of both adsorption and photocatalytie activity of complex samples increased as the surface area increased. Doping N into RH/TiO₂ samples can decrease the forming time, inhibit the transformation of crystal from anatase to rutile to some extent, improve the bond of Ti-O-Si to form and make the absorption spectrum move to the red light part. The complex samples exhibited a certain photocatalytic activity under the visible light region. The reaction rate of visible light photodegradation process arrived 0.0143 min^-1, meeting with the first-order reaction kinetics.

Abstract: The Cu₃N films were deposited successfully by reactive direct current magnetron sputtering, the films were comprehensively and systematically characterized by X-ray diffraction analyzer (XRD), UV-Visible spectrophotometer, four-probe resistance tester and other instruments. Results showed that under low deposition power (80W~100W), crystal orientation increased, which is attributed to higher energy under higher power. When sputtering power exceeded the value, excessive energy led to anti-sputtering hindering the process of further nucleation and growth of films. The transmittance of the films deposited under 100W reached the peak value of 78% on the scope of near-infrared light, and optical band gap (Eg) of 1.35ev. The resistivity of Cu₃N films increased from 9.68×10²Ω.cm to 2.12×10³ Ω.cm with increasing in sputtering power up to 100W.

Abstract: ZnO doped Al₂O₃ and ZrO₂ (ZAZO) thin films were deposited by the radio frequency magnetron sputtering on substrate temperature with 100°C, 150°C, 200°C, 250°C and 300°C. The surface morphology and electrical properties of the films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and four-probe tester. The results showed that the substrate temperature obviously influenced the grain size of ZAZO films. The ZnO thin film had the largest crystallization orientation for the (002) peak and the smallest FWHM value at substrate temperature of 250°C. As the temperature increasing, the resistance of films gradually decreased till reaching a minimum at 250°C and then rised. Due to the increasing of Al and Zr concentrations into ZnO lattice, the Al ions created an abundance number of free electrons in the ZnO lattice, and in turn, the electrical conductivity increased. In addition, the improvement of film in the crystalline state results in the film resistivity decreases.

Abstract: Integrated iron and steel enterprises is taken as the research object. Under the guidance of GHG Protocol standards for carbon emissions, the carbon dioxide accounting models on the process as a whole boundary are established, in which, the carbon emissions inventory is divided into three levels and the input data consists of CO₂ emission coefficient and activity factor level data. The process model is the accounting model that the carbon emission is obtained through the balance of carbon input and carbon output outside the process boundary under the condition of considering the enterprise circulation. This article also researched one integrated iron and steel enterprise as a case. The results show that the model can quantify the emissions of different processes, provide basic value for the enterprise reduction, Identify major carbon source, identify the influence on carbon emissions by the changes of fuel structure, the structure of the process parameters and outsourcing by-product internal circulation. Therefore the model results can be used in the carbon emissions of enterprise internal assessment and decision-making.

Abstract: Cu₃N thin films can potentially be used for development of optical storage devices and integrate circuit of semiconductor. In this study the Cu₃N films were deposited on glass substrate successfully by reactive direct current magnetron sputtering at different N₂/(N₂+Ar) flow ratio. The results showed that the nitrogen partial pressure affected the preferring orientation of the thin films when the sputtering power and substrate temperature was fixed. With increasing N₂/(N₂+Ar) flow ratio from 10% to 90%, Cu₃N(111) orientation with rich-copper changed to Cu₃N(100) orientation with rich nitrogen, the transmittance of the thin films improved gradually, and the corresponding optical band gap (Eg) increased from 1.10 eV to 1.21eV. The resistivity of copper nitrogen films changed from 5.62Ω.cm to 3.00×10³Ω.cm at the scope of 10%~90% of N₂/(N₂+Ar) flow ratio.

Abstract: Sulfate reducing bacteria (SRB) are traditionally considered as anaerobic organism. In this paper, the potential of sulfate reducing bacteria to cause mild steel corrosion under aerobic situation was investigated. Natural biopolymer agar and sulfate reducing bacteria cells were used to produce artificial biofilm. Micro-sensors were used to investigate the microenvironment in artificial biofilm. Environmental scanning electron microscopy and energy dispersive spectroscopy were used to study mild steel corrosion covered by artificial biofilm. The results indicated that SRB could grow and reduce sulfate both in suspension and in biofilm. The hydrogen sulfide produced by SRB and mild steel corrosion were influenced by the nutrients in the environment. The concentration of H₂S in SRB biofilm exposed to culture medium was as twenty times as that exposed to marine water. The main corrosion product of mild steel in culture medium was iron sulfide, whereas the main product of mild steel in marine water was iron oxide.

Abstract: In this paper, the influence of different contents of rare earth oxides of tungsten electrodes on the welding performance has been studied. Tungsten inert gas weld was carried out on 1060 aluminum plate, using different contents of rare earth oxides of tungsten electrodes. The content of CeO₂ are 2% and 4%, the content of composite rare earth oxides (La₂O₃: CeO₂: Y₂O₃ = 1:1:3) is 4%. The mechanical properties of these welded joints were investigated. The results indicated that the loss of the CeO₂ content of 4% electrode weight was the maximum. The arc stability of the three kinds of tungsten electrodes was good. The arc static characteristic curve of the composite rare earth—tungsten electrode was lower than that of the cerium—tungsten electrode. The loss of rare earth oxides of electrode had little effect on the mechanical properties of welded joints.