Development of mould fluxes based on lime–alumina slag system for casting high aluminium TRIP steel

Abstract

With excellent strength and ductility properties, transformation induced plasticity (TRIP) steels are superior to ordinary commercial steels and have great application potential in the automobile industry. However, the continuous casting of TRIP steels is associated with challenges owing to its high aluminium content, approximately 0?5–1?8%. The reaction of aluminium near the steel/slag interface continuously changes the basicity of conventional lime–silica based mould fluxes causing variation in the flux physical properties between the solidifying shell and mould wall. Therefore, the heat transfer process is unstable and the surface quality of the as-cast slab is not guaranteed.

To reduce the reactivity of aluminium in TRIP steel during casting, it is suggested to replace the lime–silica based fluxes with a lime–alumina based mould flux, based on laboratory measurements and industrial trials.

The trials showed great improvement in the slab surface quality and no depression defect was noticed so far.     

Palladium–lead alloys for the purification of hydrogen-containing gas mixtures and the separation of hydrogen from them

Ingots of palladium alloys with 5, 8, 12, 16, and 20 wt % Pb, which correspond to the Pd-based solid solution region, are prepared by arc melting in a protective atmosphere. Foils 50 μm thick are prepared from the ingots subjected to cold rolling and intermediate vacuum annealing. The membrane characteristics of the foils, which include the strength, the hydrogen permeability, the corrosion resistance, the α ? β hydride transition temperature, and the crystal lattice parameters, have been studied. The Pd–8 wt % Pb alloy is shown to exhibit the maximum specific hydrogen permeability (2.6 N m³ mm/(m² h MPa^0.5)) at 500°C, an adequate plasticity (δ = 12%), a high strength (\({\sigma _{{u_{hard}}}}\) = 550 MPa, \({\sigma _{{u_{ann}}}}\) = 230 MPa), and corrosion resistance against one of the hydrocarbon-conversion products (CO₂), which allow us to recommend this alloy for application as the membranes in filtration membrane elements.     

Effect of fluxes on structure and luminescence properties of Y3Al5O12：Ce^3＋ phosphors

Ce3+-activated yttrium aluminum garnet (YAG) was prepared by the solid-state reaction, in which H3BO3, LiF, NaF, KF and BaF2 were used as the fluxes. The effect of fluxes on optical properties of phosphors was studied in detail, especially the fluxes of alkali fluorides, which could enhance the emission intensity and change the wavelength of emission peaks. Among these YAG:Ce phosphors, the phosphor sintered with H3BO3 and NaF exhibited the strongest emission. The emission peaks of phosphors prepared with fluxes from LiF to KF were shifted to long wavelength. The effect of NaF concentration on the emission intensity of YAG:Ce was also investigated. The value of emis-sion intensity reached the maximum when the concentration of NaF was 0.5%.     

Development of the Aluminum Powder Composite Based on the Al–Si–Ni System and Technology of Billet Fabrication of This Composite

Results of an investigation into the development of the composition and fabrication technology of compact billets of the aluminum powder composite material based on the Al–Si–Ni system for space-rocket hardware are presented. The composite production was performed as follows: initially the powder of the matrix alloy is prepared by gas sputtering, and then a mixture of the matrix alloy powder and alloying dispersed additives is subjected to mechanical alloying in high-energy apparatuses. The method of degassing the mechanically alloyed composition in a thin layer (in order to exclude material ejection from a container when degassing a larger volume of powder) and process regimes of composition compaction are developed using the unique equipment available at OAO Kompozit (Korolev, Moscow oblast)—a vacuum press. Using this technology, cylindrical briquettes up to 100 mm in diameter and up to 120 mm in height are fabricated. Newly developed and patented Kompal-301 composite material has substantial advantages over SAS-1-50 power alloy applied for similar purposes. Its thermal linear expansion coefficient is lower by a factor of 1.5, while the precision limit of elasticity is higher by a factor of 2–3 upon similar strength characteristics. The final structure of a compact briquette is a matrix in which dispersed particles of excess silicon are distributed rather uniformly against the background of the aluminum solid solution. Coarser isolated silicon particles are met in separate regions of the structure. Unfortunately, they are the cause of low plasticity of briquettes, which prevents the formation of semifinished products by plastic deformation; however, such low plasticity does not immediately negatively affect the fabrication of the briquettes themselves.     

Changing patterns of inpatient care for children and adolescents at the Menninger Clinic, 1988–1994.

The authors describe trends in inpatient psychiatric length of stay (LOS) and admissions for the population of children and adolescents (N?=?784) at the Menninger Clinic from 1988 to 1994. During this period, median LOS declined dramatically from 7 months to 3 weeks, whereas admissions increased 4-fold. The diagnostic case mix changed substantially, with a crossover in modal principal diagnosis from personality disorder to affective disorder. Use of medications became almost universal. Diagnosis and medication use became less important determinants of LOS over time. The practical implications of these patterns include higher patient turnover, fewer inpatient clinical contact hours, and heightened importance of continuity with outpatient care. Research should center on the impact of declining LOS on clinical and functional outcomes for children and adolescents. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Viscosity of Fe-P melts in the range 5–25 at % P

Damped torsional vibrations are used to study the temperature (up to 1700°C) and concentration (from 5 to 25 at % P) dependences of the kinematic viscosity of iron-phosphorus melts.     

Influence of the Structure of Fe–Si–Mg–Rare Earth Modifiers on the Production of Compacted Graphite Iron for Camshafts

The structure of a modifier in two forms (ingot and chip) for the production of compacted graphite iron (also known as vermicular graphite iron) is investigated by means of an electron microscope and also by X-ray microspectral analysis. The possibility of qualitative identification of the phase composition and surface macroanalysis of the modifier particles is considered.     

Effect of alloying by transitional refractory metals on the microstructure and thermal stability of Al–5Zn–3Mg alloys

Abstract

The effect of additions of transitional refractory metals on the structure and properties of Al–Zn–Mg alloys, made by ingot and PM routes, was investigated. The strength of the ingot alloys especially is increased by scandium and zirconium. The modifying action of scandium inhibits recrystallisation and precipitation of the fine-grained coherent Al₃(Sc_1–xZr_x) phase. The effect is weaker in PM alloys where the ultra-high cooling rate during high pressure water atomisation produces the fine-grained structure. PM semi-products of the base composition Al–5Zn–3Mg and alloys without scandium are not recrystallised during heating to 500°C, whereas cast alloys of similar composition recrystallised on the hot extrusion stage at 400–450°C. Of the Sc alloys, Al–5Zn–3Mg–0·5Mn–0·7Zr–0·3Sc showed the highest strength (UTS?=?651 MPa, YS?=?596 MPa), whereas of the PM alloys without scandium Al–5Zn–3Mg–0·85Zr–0·22Cr–0·17Ni–0·15Ti alloy showed UTS?=?618 MPa and YS?=?553 MPa. At melt cooling rates of 10⁵–10⁶ K s^–1 the total content of transitional refractory metals must not exceed 1·5–1·7 wt-% and total content (Zn+Mg) should be <8 wt-% at a Zn/Mg ratio of 5:3.     

A Study on the Kinetics of the Europium Electrochemistry Reduction 1.The Polarization Properties of Europium Reduced at the Cathode

This article studies the polarization properties of the cathode reduction of Eu in the Sm-Eu-Gdchloride system by using a constant potential method.As the feed concentration,temperature,and stirringrate of the system change,the system can gradually turn from chemical polarization to concentrationpolarization,and there would be a higher limiting current.As to the effects of acidity,only at a rather higherpH there will be a typical polarization property.The study can give some bases for the Eu electroreductiontechnlolgy parameter selection.     

Phase Equilibria in the Ternary Al–Ti–Pt System. II. Liquidus Surface of the Al–Ti–Pt System in the Compositions Range 0–50 at.% Pt

Powder Metallurgy and Metal Ceramics - The liquidus surface of the Al–Ti–Pt system has been constructed for the first time on the composition triangle based on studies of the structure...     

The Redox Kinetics of the Oxidation for CO on EuFeO_3 Catalyst

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The Influence of Deformation Modes on the Structure and Properties of Al–Mg–X Powder Composites. III. The Influence of Nanosized SiC Powder Content and Deformation Processing on the Properties of AMg5 Alloy Powder Composites

Powder Metallurgy and Metal Ceramics - The structure and mechanical properties of a powder composite with an AMg5 alloy metallic matrix reinforced with SiC particles have been examined. The...