Development of Semi—Graphite Carbon—Silicon Carbide Brick and Its Application in Slag Forming Zone of Large—sized Blast Furnace

Based on the damage mechanism of the lining at the slag forming zone of the blast furnace and the charactieristics of various refractory ma-terials,the methods to increase the service life of the lining at the slag forming zone have been found:(1) to improve the capacity of the blast furnace brick lining subjet to heat impact;(2) to reduce the working side temperature of the brick lining.On this basis,the semi-graphitized ,high temperature electrically calcined anthracite and silicon carbide etc ,were used as the main raw materials,Through a lot of experiments the proper raw material mix and grain size compo-sition were determined,In addition ,a suitable amount of additives and binders was added.After high pressur forming,high temperature firing and grinding ,the semi-graphitic carbon-silicon carbide bricks with close dimension tler-ances and ideal physical and chemical properties have been made.They have been applied in some blast furnaces,such as No.11(2580 m^3) and No.6(1050 m^3) blast furnaces etc.at Anshan Iron and Steel Company,and the problem of short service life at slag forming zone of blast furnace has been solved.     

Mullite Coating on Recrytallized Silicon Carbide and Its Cycling Oxidation Behavior

1IntroductionThere are strong interests in identifying approa-ches to protect silicon carbide ceramics from high tem-perature oxidative environments and prolong their serv-ice lives.One method is to apply a refractory coating.The advantage of coating tech…     

Laplacian Growth Models for Porous Silicon Formation—Stability Analysis

We develop a Laplacian model of interface growth which includes basic features of the anodisation of silicon in hydrofluoric acid. Our aim is to find mechanisms for the characteristic properties of porous silicon formation, such as the transition from electropolishing to pore formation and the typical pore distance. The local etching rate of the interface between the semiconductor and the electrolyte is determined by the local current density. We model the diffusive transport of charge carriers in the semiconductor and of reactants in the electrolyte including the basic features of the electrochemical reaction at the interface. A linear stability analysis of a flat and planar interface is performed in order to study the initial state of pore formation.     

Anisotropic Properties in Hot Pressed Silicon Nitride—Silicon Carbide Platelet Reinforced Composites

The anisotropic properties (microstructure, mechanical properties) of a hot-pressed platelet reinforced silicon nitride composite were compared with those of the monolithic material. The platelets appeared to be orientated with their basal plane in the compressive plane, and to be embedded in a silicon nitride matrix consisting of interlocked elongated β-Si₃N₄ grains with their c axis orientated in this plane. TEM analysis showed an interface, consisting of glassy phase and graphite at the platelet–matrix grain boundary. Moreover the interfacial tensile stresses are in favour of a crack deflection mechanism. It was shown by TEM analysis that crack deflection occurs not only at the silicon nitride–platelet interface, but also at silicon nitride–silicon nitride grain boundaries. The efficiency of this reinforcing mechanism is highly orientation dependent. Because of their two dimensional geometry compared to the one-dimensional β-Si₃N₄ grains, platelets increase the toughness in two dimensions.     

The Mechanism of Silicon and Silicon Carbide Making Carbon—containing Materials Antioxidize

The paper analyses redox reactions of an-tioxidants Si and SiC ete at different positions in the course of oxidation of carbon-containing materials,It is pointed out that redox reaction of antioxidants in oxidized-zone plays a very important part in antioxidation of carbon-con-taining materials,The reason why SiC can make carbon-containing material antioxide at thermodynamic temperature has been ex-plained,Experiment proves that antioxidants in oxidized zone can make carbon-containing materils antioxidize.     

Chemical Analysis Method for Magnesia and Magnesia-Alumina Refractories——Gravimetric-Molybdenum Blue Photometric Method for Determination of Silicon Dioxide Content

GB/T 5069.3-2001 1 Scope This standard specifies the gravimetric-molybdenum blue photometric method for determination of silicon dioyide content.This standard is used for the determination of silicon dioxide content of magnesia and magnesia-alumina refractory materials. Determination range: >5.00%.     

Luminescence in Porous Silicon—Surface vs. Bulk

The mechanism of luminescence in porous silicon still remains poorly understood. The main point of controversy is whether the luminescence is due to recombination in the quantum size structures that constitute porous silicon or whether it is dominated by surface recombination. In this paper, we present evidence that emphasises the role that surface recombination plays in the luminescence of porous silicon. In this framework, we also attempt to reconcile the resonant luminescence data (which argues for bulk recombination) with our results.     

Long Spacing in Polyblock Poly(ether ester)s—Origin and Peculiarities

Abstract

Poly(ether ester)s (PEE) based on poly(butylene terephthalate) (PBT) as hard segments and poly(ethylene glycols) (PEG) with different molecular weight as soft segments are studied by means of WAXS and SAXS in the drawn and undrawn state after annealing at various temperatures (T_a ). The repeatedly reported strong increase of the long spacing L with T_a is confirmed once again. In the same time the directly measured by WAXS crystallite size of PBT remains insensitive to T_a and the increase of L with T_a is the stronger, the higher the PEG content. It is concluded therefore that the rise in L is due to the expansion of the amorphous intercrystalline layers rather than to crystal thickening, the latter being the case of semicrystalline homopolymers.

The observed much stronger increase of L with T_a in undrawn samples than in drawn ones is explained by melting of less perfect crystallites at higher T_a and dephasing processes in the amorphous regions. The conclusions drawn seem to be valid for other segmented polyblock copolymers and suggest some specific features of the block copolymers in comparison to homopolymers.     

A Robust Statistical Batch Process Monitoring Framework and Its Application

In order to reduce the variations of the product quality in batch processes, multivariate statistical process control methods according to multi-way principal component analysis (MPCA) or multi-way projection to latent structure (MPLS) were proposed for on-line batch process monitoring. However, they are based on the decomposition of relative covariance matrix and strongly affected by outlying observations. In this paper, in view of an efficient projection pursuit algorithm, a robust statistical batch process monitoring (RSBPM) framework, which is resistant to outliers, is proposed to reduce the high demand for modeling data. The construction of robust normal operating condition model and robust control limits are discussed in detail. It is evaluated on monitoring an industrial streptomycin fermentation process and compared with the conventional MPCA. The results show that the RSBPM framework is resistant to possible outliers and the robustness is confirmed.     

Effect of Laser Treatment on Surface and Interface of Silicon Nitride Coated Ti6Al7Nb Alloy – A Statistical Analysis

Silicon - The current research work investigates the impact of laser treatment on Silicon Nitride (SiN) coating and its performance in the bio-tribological environment. The Cathodic Arc Deposited...     

The Microstructure and Properties of Alumina—Rich Spinel and Its Products

The paper describes the effect of chemical composition on the microstructure and properties of spinel specimens synthesized from bauxite and magnesite,The alumina-rich spinel with higher ratio of Al2O3/MgO,with smaller spinel grain,contains more titaniferous mineral and silicate phase compared to the spinel with lower Al2O3/MgO ratio.In the products obtained from alumina-rich spinel and magnesite clinker,the ratio of Al2O3/MgO of spinel decreases,ti-taniferous mineral and silicate phase in the spinel aggregate are changed,and its content tends to degradation,contrasted with original alumina-rich spinel,The products have good high temperature properties.     

Diphonix® Resin: A Review of Its Properties and Applications

Abstract

The recently developed Diphonix® resin is a new multifunctional chelating ion exchange resin containing geminally substituted diphosphonic acid ligands chemically bonded to a styrene-based polymeric matrix. Diphonix can be regarded as a dual mechanism polymer, with a sulfonic acid cation exchange group allowing for rapid access, mostly non-specific, of ions into the polymeric network, and the diphosphonic acid group responsible for specificity (recognition) for a number of metal cations. The Diphonix resin exhibits an extraordinarily strong affinity for actinides, especially in the tetra- and hexavalent oxidation states. Therefore the resin has potential for applications in TRU and mixed waste treatment and characterization, and in the development of new procedures for rapid actinide preconcentration and separation from environmental samples. Metal uptake studies have been extended to alkaline earth cations, to transition and post-transition metal species, and to metal sorption from neutral or near neutral solutions. Also the kinetic behavior of the resin has been investigated in detail. In view of the above applications the influence of the most commonly occurring matrix constituents (Na, Ca, Al, Fe, hydrofluoric, sulfuric, oxalic and phosphoric acids) on the uptake of actinide ions has been measured. This review paper summarizes the most important results obtained in the studies on the properties of the Diphonix resin and gives an overview of the applications already in existence or under development in the fields of mixed waste treatment, actinide separation procedures, treatment of radwaste from nuclear power and fuel processing plants, and removal of iron from copper electrowinning solutions.

     

Analysis to the Petrochemical Market in China and Projection

Stimulated by the economic growth,thepetrochemical market in China featuredbrisk demand,robust investment andincreased profit in 2004 and the petro-chemical industry entered a new cycleof prosperity.The petrochemical industry is a ba-sic raw material industry and holds anextremely important position in the de-velopment of the national economy.Itis closely related to various departmentsof the national economy and people'sliving standard.The ethylene industrywill have another great development     

Clays and oxide minerals as catalysts and nanocatalysts in Fenton-like reactions — A review

Advanced oxidation processes (AOP), involving the generation of highly oxidizing radical species, have attracted much attention because of their potential in eliminating recalcitrant organic pollutants from different environmental matrices. Among the most investigated AOP is the Fenton reaction in which hydroxyl radicals (HO) are generated through the catalytic reaction of Fe(II)/Fe(III) in the presence of hydrogen peroxide. The use of clays and iron-oxide minerals as catalysts of Fenton-like reactions is a promising alternative for the decontamination of soils, groundwaters, sediments, and industrial effluents. The low cost, abundance, and environmentally friendly nature of clay minerals and iron oxides are an added advantage. Additionally, the introduction of nanoparticles in heterogeneous catalytic processes has led to appreciable improvements in catalytic efficiency. Here we review the application of clays and iron-oxide minerals as supports or active catalysts in Fenton-like reactions, and summarize the latest advances in nanocatalyst development. We also evaluate the potential use of allophane nanoparticles, coated with iron oxides, as catalysts of Fenton-like reactions.     

A Modified Model for Flexibility Analysis in Chemical Engineering Processes

This paper discussed an extended model for flexibility analysis of chemical process. Under uncertainty, probability density function is used to describe uncertain parameters instead of hyper-rectangle, and chance-constrained programming is a feasible way to deal with the violation of constraints. Because the feasible region of control variables would change along with uncertain parameters, its smallest acceptable size threshold is presented to ensure the controllability condition. By synthesizing the considerations mentioned above, a modified model can describe the flexibility analysis problem more exactly. Then a hybrid algorithm, which integrates: stochastic simulation and genetic algorithm, is applied to solve this model and maximize the flexibility region. Both numerical and chemical process examples are presented to demonstrate the effectiveness of the method.     

Protected Designation of Origin Extra Virgin Olive Oils Assessment by Nuclear Magnetic Resonance and Multivariate Statistical Analysis: “Terra di Bari”, an Apulian (Southeast Italy) Case Study

We report a study on the chemical characterization of 102 monovarietal micro‐extracted and genetically characterized extra virgin olive oils (EVOOs) from Coratina, Ogliarola Barese and Cima di Mola cultivar, according to “Terra di Bari” (Apulia, southeast Italy) PDO requirement. Three additional geographical mentions, all belonging to the same Bari district (Bitonto, Castel del Monte and Murgia dei Trulli e delle Grotte), were studied and potential microclimate differences were evaluated. Our results indicate the possibility of distinguishing EVOOs from the same “Terra di Bari” PDO with respect to different cultivars and (to some extent) different subareas. In particular, two cultivars (Ogliarola Barese and Coratina), obtained from the same Bitonto area, and a single cultivar (Coratina), obtained from Bitonto and Castel del Monte subareas, were compared to investigate the micro‐area pedoclimatic effect. Finally, ¹H NMR data were found significant for classification purposes of unknown EVOO samples, the results of which were included in the model space, as they were correctly predicted by the OPLS‐DA obtained by ¹H NMR data. This work aims to classify commercial “Terra di Bari” PDO EVOOs by comparison of the declared cultivar and geographical origin with a reference dataset of genetically characterized micro‐extracted monovarietal oils. In conclusion, the effect of the pedoclimatic micro‐areas of origin on the Coratina cultivar, which is the main component of the “Terra di Bari” PDO, has been studied in order to improve the traceability of the raw material used to produce this valuable food.     

Structure of Coreless, Long Silicon Carbide Fibres and Aluminum—SiC Composites

Using electron microscopic, x-ray, and sorption methods, the internal structure, surface, and porosity of coreless silicon carbide fibres and composites were investigated. A model of the interaction at the aluminum melt —SiC fibre interface was proposed. The effect of low-temperature annealing on the structure and properties of domestic and Japanese coreless silicon carbide fibres was observed. The reaction rate in composites reinforced with domestic annealed fibres decreased.