Papers by Keyword: Crystallization Process

Abstract: Electro-slag re-melting (ESR) is a process that combines all important elements of steel melting conversion. JSC “RPA “CNIITMASH” continuously developed ways to use ESR to manufacture critically important parts for power engineering, including nuclear power engineering, heavy-duty machine engineering and other machine building industries. Enhanced performance of product is an important competitive advantage that ESR provides in comparison to other metallurgical processes. Present report reflects results of the latest research work aimed at resolving issues related to control and management of refining and crystallization processes, cost reduction for ESR products. Practical relevance of developed approach to control of ESR metal quality is revealed by data of achieved parameters which characterize properties of pipes and pipeline elements in energy and nuclear power industries which rely on ESR ingots as work-piece blanks.

Abstract: SrO-Al₂O₃ ceramics has prospective applications due to its photo-luminescence and persistent afterglow properties. Sr₃Al₂O₆-SrAl₂O₄ eutectic glass was prepared by using the aerodynamic levitator equipped with a CO₂ laser device. The prepared Sr₃Al₂O₆-SrAl₂O₄ eutectic glass beads were further heat-treated at temperature from 880°C to 980°C. The phase evolution, crystallization behavior, optical transmittance and mechanical properties of the annealed eutectic glass ceramics were investigated. The as-prepared glass is colorless and transparent over a wide range from ultraviolet to near-infrared region, and the average in-line transmittance is over 80% in the range of 260-3200nm. There were two crystal phases Sr₃Al₂O₆ and SrAl₂O₄ crystallized from the glass beads. With increasing heat-treatment temperature, the transparency of the samples decreased, and the hardness increased. The prepared Sr₃Al₂O₆-SrAl₂O₄ eutectic glass and glass ceramics may be a promising candidate for the development of photo-luminescence and persistent afterglow materials.

Abstract: The paper deals with simulation of linear crystallizer work process for the research of technic operating modes and searching the most effective for material’s nano-purity achievement. The model is realized by using SimSar software. Importance of device's geometry and process variables are marked. The model was included in the complex’s composition of closed nuclear fuel cycle

Abstract: The paper presents tests determining the influence of modification with phosphorus and fast cooling on the microstructure and friction coefficient of AlSi17Cu5Mg alloy. Changes mainly concern the size of primary silicon crystals and stereological parameters in reference to initial material. Modification with fast cooling was aimed at achievement of fine-crystalline structure with shapes of silicon crystals close to the spherical shape. The consequences of such activities are visible, significant changes in the tribological properties of tested alloy. Friction coefficient μ for material subject to fast cooling was on the level of 0.26 and for initial material it equalled 0.29.

Abstract: This paper covers the investigation of the microstructure and magnetic properties of amorphous magnetic alloy Fe78Ni1Si9B12 films, which was subjected to thermal processing. Study of the surface with the help of phase analysis and Kikuchi-diffraction revealed the change of state of the alloy surface without the influence on its volume.

Abstract: The aim of this work is to present experimental results of investigation on crystallization process of Co-containing Finemet-type alloys. To different Finemet alloys, there exist different changing trends of the initial crystallization temperature after Co addition. Addition of Co in Fe_73.5Cu₁Nb₃Si_13.5B₉ alloy reduces the stability of the amorphous phase, and leads to the formation of nanocrystallites at lower temperature. While adding Co increases the stability of Fe_76.9Cu_0.6Nb_2.5Si₁₁B₉ amorphous phase, and results in higher nanocrystallites temperature. Using the method of Kissinger, possible reasons were analyzed for the variation of the apparent activation energy of crystallization determined from DSC thermograms.

Abstract: The crystallisation mechanism of glass-ceramic materials from a CMAS group Al0.37B0.34Fe0.01Mg0.02Zn0.29Ca0.05Si0.78O3 was tested under non-isothermal conditions by the DTA method. Glass-ceramic material of two-phase composition with precipitation of crystallites from islet silicates Zn2SiO4 and a crystalline phase from a spinel group, gahnite ZnAl2O4 was obtained in the system under investigation. Activation energy of a crystallization process Ea was determined and a crystal growth morphology parameter n was computed. It was revealed that in the test material from a CMAS group one could obtain the crystalline phase in the form of ghanite as a result of a controlled process of crystallization. The occurrence of a spinel phase caused the obtained glass-ceramic material had higher fracture toughness (KIC) than material from a CMAS group, containing pyroxene crystalline phases typical for this system.