Papers by Keyword: Glass Phase

Abstract: The expediency of processing iron-containing concentrate with low iron content, increased content of manganese and copper is considered in the article. To process such a concentrate, a metallization process is proposed to produce sponge iron with a reducing agent - carbon. It was found that in solid-phase reduction at 1150 °C iron is reduced to a greater extent, as well as small particles with a copper content of about 95%, manganese is not recovered. The simulation process of metallization with carbon at a temperature of 1250 °C shows that iron is mainly distributed in the metallic phase, to a lesser extent in slag phases, manganese is distributed in two phases - metal and slag, copper is presented as a separate phase of metallic copper in the composition with iron alloys, and also composes a part of iron alloys. The reduction degree from concentrate to the metallic part is 80 - 91% for iron and 95 - 98% for copper. The presence of metallized particles of various sizes, representing phases of iron with manganese and copper was found in the slags.

Abstract: . The ground granulated slag is a wide spread component of various types of cement and binding substances. Its pozzolanic activity depends on different factors. It is searched out, that there are no minerals able to liquid maturing in the slag under consideration, the slag activity data according to domestic and foreign standards specifies it as low-active, third rate. Altering the chemical composition to a small degree, specific to a definite type of slag, does not alter its functioning much. The same stands for the slag dispersiveness at the high rate of amorphous state – the dispersiveness rise increases slag activity and water demand, and more dispersed slag does not increase the resistibility of matrix samples in high-flow concrete mix. Thus, this type of slag is supposed to be grounded up to BET surface area equal to 250-300 m²/kg, compared to dispersive capacity СEM 1, and the substitution of a part of cement by slag would not have a significant ifluence on mix water demand. With the increase in the slag content within the cementing component the slag effectiveness index increases and reaches its maximum at 70% cement replacement by slag. A large portion of slag can substantially decrease the hydration of lime in the hardened cement paste of the concrete and lessen the solidity of reinforcement corrosion protection in concrete structures. The article deals with different methods of ground granulated blastfurnace slag activation within the mixed cementing substance: Portland-cement CEM1 + GGBFS. The most widely used way of activation – the usage of sodium and potassium alkalies and liquid glass is quite effective, but it demands expensive artificial components, while the alkali compounds forming at hardening of such a cementing component would be soluble.

Abstract: A new adhesive reagent has been developed for the fabrication of shell mold with the adhesive strength under high temperature. The new adhesive reagent was prepared by mixing inorganic precursors of alkyl silicate and sodium alkoxide, starting particle composed of silica (SiO2) and alumina (Al2O3) used as substrate in the conventional mold process, and colloidal silica. Inorganic precursor was used to increase the adhesive strength of mold, resulting from the glass phase generated by the sol-gel reaction and glassification of precursors. In addition, colloidal silica and starting particle were added to control the viscosity of adhesive reagent, inducing the availability of adhesive reagent. In the case of mold sample adjoined by the new adhesive reagent the glass phase is well formed at the interface between adhesive reagent and substrate, compared with those made with the conventional adhesive reagents such as a mortar and a sand bond. This leads to the increase in the adhesive strength of shell mold, preventing the collapse of the mold at a high temperature during casting process. Therefore, the new adhesive reagent could desirably prepare shell mold without an additional process to enhance the adhesive strength in the conventional casting process.

Abstract: Mullite- corundum insulation material with nano crystals in matrix was fabricated by gel-casting process. The results showed that the volatilization temperature of organisms is 285°C- 600°C, there is no glass phase appeared in specimens; The mullitization begin at 1000°C, along with the raise of temperature, the quantity of mullite phase increases, especially during 1200°C- 1400°C; when the temperature is up to 1550°C, mullite becomes the main crystal phase and there are also some corundum crystals in the specimens; The specimen matrix sintered at 1550°C is consisted of nano crystals 80nm in length and 10-20nm in diameter.

Abstract: The development of consumer electronics has meant that the component market is subjected of major economic issues. The economic battle goes through a search of lower manufacturing costs of electronic components together with an improvement in their performance, especially multilayer ceramic capacitors. The dielectric properties of the compound MgTiO3 (r  17, ε =100 ppm/°C, Tan (δ) <10-3) make this material a very good candidate for the manufacture of multilayer capacitors. In contrast, the high sintering temperature of this ceramic (1350 ° C), precludes the realization of multilayer capacitors with copper inner electrodes (T melting = 1083 ° C) less expensive than noble metals (Pd or Pt). Recent studies have shown that it is possible to reduce the sintering temperature by adding sintering agents. Additions made on MgTiO3 are glass phases (BBS 5Z2B, SBAZN, BBZS). Interesting dielectric properties were obtained in the case of system MgTiO3 + BBZS sintered at 1030 ° C: a dielectric permittivity epsilon r = 15.46, a temperature coefficient of 207 ppm / ° C, dielectric losses Tan (δ) <10-3.

Abstract: This paper studies the blast furnace slag glass phase structure by a series of analysis methods. In glass phase, both Si and Al ions are confirmed to occupy only tetrahedral sites, while the [SiO4]4- and [AlO4]5- are separated by Ca and Mg. Furthermore, the glass structure corresponds to micro-crystal model, which means it contains some nano-scaled micro-crystals in the glass phase. In addition, the slag glass may separate into two phases: a calcium rich phase and a silica rich phase. According to devitrification experiment, it has been inferred that the chemical composition and structure of silica rich phase are close to that of akermanite,which means most of Si is distribute around Mg.

Abstract: In a high-purity 8Y-CSZ, the doping of 0.15 - 5 mass% pure silica introduces a glass phase dispersing uniformly along grain-boundary facets and at multiple junctions. For materials with grain sizes of 0.75 - 2.4 m, the dispersion of the glass phase decreases the elastic modulus, the Vickers hardness and the elastic modulus-to-hardness ratio, whereas it affects little in the fracture toughness measured by a Vickers-indentation method and a single-crack-precracked-beam method. Inspection of crack propagation paths shows that the glass phase with sizes smaller than those of the matrix grains is not a site for easy crack-propagation, but provides a site for a crack-deflection mechanism.

Abstract: Ceramic radiator fins were produced by screen-printing copper paste on ceramic substrate, which could replace the traditional technique of direct bestrow copper and meet the requirements of surface mounted technology. This method could be used to manufacture high density, superior thin and micro-sized molectrons. The key processes were screen-printing copper paste, sintering and electroless plating of nickel. The adhesion of copper film onto the ceramic substrate was often reduced after the process of electroless plating of nickel, resulting in the low quality of manufacturing. In this study, we analyzed the ceramic radiator fins which were obtained by the screen-printing copper paste method and using scanning electron microscopy to examine the surface and the cross-sections of copper film and Cu/Ni film. The adhesive properties of copper film during electroless plating was studied. The corrosion resistance of copper film and sintering glass phase on alumina substrate (96%) was also studied in an electroplating bath. The study revealed that the glass phase of acidity of silicon, softening temperature, the interaction conjunction between glass phase and ceramics were important factors.