tration between 0.1 and 0.2 mg/l, but at a glue concentration of about 0.8 mg/l. Further advantages of PEG compared with glue are the clearly slower chemical decomposition rate, the possibility of setting a definite cathodic potential by variation of the molecular weight and the constant chemical composition. However, our systematic investigations have shown that there will be no improvement in the deposition type of the cathode deposits when PEG is only added compared with the classical inhibitor system of glue and thiourea until now. It is known in copper electrorefining and electroplating that a high quality of cathodic deposition can usually only be achieved through a combination of inhibitors and activators. The major target of our further investigations is to find additives that show a depolarizing effect in combination with PEG. In addition to that criterion these additives should be sulfurfree to reduce the level of sulfur in the cathodes in comparison to the traditional used thiourea.As the new generation of secondary metallurgy and advanced continuous casting technologies have been developed in the last decade, refractory materials have met the greatest challenge in order to secure the high metal quality under economical and ecological aspects. During service refractories must not only tolerate high temperature but also withstand stresses (thermal and/or mechanical) as well as resist combined attacks by liquids such as molten metals, slags and fluxes. Especially in near net shape casting technologies enhanced corrosion and erosion performance is required followed by thin wall thickness design of functional components such as submerged entry nozzles or casting channels. [1,2] In addition the processing of these advanced refractories has to fulfil all the requirements for a large geometry component manufacturing whereby the task of low shrinkage during firing dominates.In recent years the Institute of Ceramic, Glass and Construction Materials of the Technische Universität Bergakademie Freiberg has been involved in research studies of process and material development of MgO carbon bonded materials (MgO-C) as high-performance refractory ceramics because of their superior properties according to corrosion and thermal shock resistance as well as the unique benefits out of a low shrinkage pyrolisis firing process. MgO-C refractories are established construction materials of converters, electric-arc furnaces, transfer and treatment ladles. [3] The carbon increases the corrosion resistance of magnesia carbon bricks caused by all types of liquids (molten slag and metals) and improves their thermomechanical properties, particularly their thermal shock resistance. In addition carbon offers excellent electrical properties in order to use these advanced refractories also as smart, functional refractories and especially as smart refractory casting components.
In the last years several attempts have been made in order to lower the emissions from carbon bonded refractories by keeping or improving the mechanical, thermal and chemical properties.The introduction of carbo-resins opens the horizon for a low emission binder system in the so called cold processing of carbon bonded refractories. In terms of this work a variety of phenolic resin binders has been combined with carbo-resin in order to improve the anisotropic structure for advanced chemical and thermo mechanical properties with 14 wt.% residual carbon. Samples from industrial bricks have been used in order to measure the cold crushing strength, the hot modulus of rupture and the oxidation behaviour. The microstructure has been evaluated due to SEMmicrographs and porosimetry. In a further step corrosion finger tests have been carried out by simulating the oscillation of the mould and relative movement of the steel and the slag against the refractory component. The investigations have been completed by flexibility measurements in a special device by defining the stress/strain behaviour.Due to the new binder combinations the task of lowering emissions as well as improving the mechanical and thermal performance has been achieved.
No abstract
Technology is introduced for the first time in the CIS area for making the working lining of CBCM intermediate ladles of the OAO MK AzovStal' converter workshop with "dry" periclase mix. Supply of the mix, technology transfer for its application, and supply of equipment for making the lining is accomplished by Gruppa Magnezit (Dalmond).
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