Taishi Matsushita

Density and excess volumes of liquid copper, cobalt, iron and their binary and ternary alloys

Abstract The densities of liquid copper, cobalt, and iron, their binary and ternary alloys have been measured over a temperature range including the undercooled regime. A non-contact technique was used, consisting of electromagnetic levitation combined with optical dilatometry. For all samples, the density was a linear function of temperature. The concentration dependence was studied by means of the excess volume which was negligible for Co–Fe and positive for Cu–Fe, Cu–Co, and Cu–Co–Fe. The density of the ternary alloy could be predicted from the excess volumes of the binary phases without the need to introduce any ternary interactions.

Estimation of molar volumes of some binary slags from enthalpies of mixing

In an effort to interlink the thermo chemical and thermo physical properties of slags, the present workwas undertaken to derive the molar volumes of complex slags from the enthalpies of mixing of t ...

Thermochemical and thermophysical property measurements in slag systems

This paper reviews developments on experimental methods and results of thermochemical and thermophysical property measurements of molten silicate slag systems and its theoretical achievements. Several selected topics are focused on, including experimental procedure and measurements of viscosity, density, surface-interfacial tension, thermal conductivity, thermal diffusivity and velocity and absorption coefficient of ultrasonic waves. Thermal conductivity and diffusivity of slags have been mainly measured by the transient techniques such as the laser flash and hot wire methods. Most of the measurements for velocity and absorption coefficient of ultrasonic waves are carried out using a pulse technique. The reliable data for thermochemical and thermophysical properties are required for the optimisation of metallurgical processes and the data is needed in order to improve the numerical models of processing. For academic interest, the results were discussed from the viewpoint of slag structure, as these properties are closely related to the slag structure.

Influence of alumina on physical properties of an industrial zinc-copper smelting slag Part 3 - melting behaviour

Abstract A combination of different experimental techniques and thermodynamic calculations has been used to investigate the melting behaviour of an industrial iron silicate slag and mixtures of this slag with 5, 10 and 15 wt-% alumina addition. Differential scanning calorimetry (DSC) and thermo-optical observation were applied to monitor the solidus temperature and softening behaviour of the samples respectively. Estimation of the liquidus temperature was made using the second derivative of activation energies for viscous flow, with respect to temperature. All experimentally detected values were compared to predictions made using the FactSageTM6·2 thermodynamic package. Results show that as the slag lies in the fayalite primary phase field, the liquidus temperature decreases due to the increased alumina concentration. In the hercynite primary crystallisation phase field, however, alumina addition to the system increases the liquidus temperature. The solidus temperature does not vary significantly due to the current changes in the total alumina content of the slag.

Influence of alumina on physical properties of an industrial zinc-copper smelting slagPart 1 – viscosity

Abstract The rotating cylinder method was applied to measure the viscosities of an industrial iron silicate slag and mixtures of this slag with 5, 10 and 15 wt-% alumina addition, in temperature range 1100–1300°C. The measured viscosities were compared with the predicted values using two of the commercially available software products for viscosity calculations, namely Thermoslag®1·5 and FactSageTM6·2. As the models can only predict viscosities for a solid free melt, obtained values by FactSageTM6·2 were modified using the Einstein–Roscoe equation. Results show that aluminium behaves as a network former cation in this type of slag, and by increasing the alumina concentration, the melt becomes progressively polymerised. Consequently, the viscosity of the slag increases at a given temperature, which is supported by thermodynamic predictions. According to the modified FactSageTM6·2 calculations, the viscosity of the solid containing slag increases from 2·1 to 5·5 poise at the industrial operating temperature (∼1250°C).

Thermal, optical and surface/interfacial properties of molten slag systems

Abstract In modelling mass and heat transfer steps in metallurgical processes, it is important to have knowledge of the physical properties of slags, the most important among these being the surface and interfacial tensions, thermal diffusivities, optical properties and viscosities. A critical review is presented of work reported in the past two decades relating to the following properties of slag systems: (i) surface/interfacial tensions and related interfacial phenomena; (ii) thermal diffusivities and thermal conductivities; (iii) velocities and coefficients of absorption of ultrasonic waves; (iv) optical properties. A perspective for further work is also provided.

Influence of alumina on physical properties of an industrial zinc-copper smelting slag : Part 2 - Apparent density, surface tension and effective thermal diffusivity

Abstract Apparent density, surface tension and effective thermal diffusivity of an industrial iron–silicate based slag and mixtures of this slag with 5, 10 and 15 wt-% alumina addition were measured using the sessile drop and the laser flash techniques respectively. A comparison is made between corresponding values obtained from the commonly applied models and the experimental measurements. Results show that increasing the alumina concentration in slag increases the degree of polymerisation of the melt and, consequently, its effective thermal diffusivity. By alumina addition to the system, the surface tension increases progressively from 338 mN m−1, in the reference slag sample, to 488 mN m−1 in the mixture of slag and 15 wt-% alumina addition. The apparent density of the liquid–solid containing slag is continuously decreased due to the increased alumina concentration. However, the effect is more pronounced between 8 and 12 wt-% total alumina content in the slag.

On the thermal conductivity of CGI and SGI cast irons

Abstract The thermal conductivity of Compacted Graphite Iron (CGI) and spheroidal graphite iron (SGI) was established in the temperature range from room temperature up to 500 °C using the experimental thermal diffusivity, density and specific heat values. The influence of nodularity, graphite amount, silicon content and temperature on the thermal conductivity of fully ferritic high-silicon cast irons was investigated. It was found that the CGI materials showed higher thermal conductivity than the SGI materials. The thermal conductivity tended to increase with increasing temperature until it reached a maximum followed by a subsequent decrease as temperature was increased up to 500 °C. Conventional models were applied to estimate thermal conductivity and the predictive accuracy of each model was evaluated. The thermal conductivity could be estimated by the Helsing model. The Maxwell model, Bruggeman model and Hashin–Shtrikman model were also in fair agreement using the thermal conductivity value of graphite parallel to the basal planes in graphite.

ThermoLab project : Results on Thermophysical Properties Data of Iron Alloys

As a part of ThermoLab project, the thermophysicalproperties of industrially important iron alloys weremeasured. In this paper, the measurement results of thedifferential scanning calorimetry (DSC) ...

A particle population analysis in Ti- and Al- deoxidized Hadfield steels

Abstract A quantitative analysis of the amount, size and number of particles that precipitate in situ in titanium- and aluminium-treated Hadfield steel cast during pilot-scale experiments has been performed. SEM with EDS and automated particle analysis abilities was utilized for the analysis. Additionally, Thermo-Calc was used for thermodynamic calculations and Magma 5 for solidification and cooling simulations. Predicted particles sizes calculated with a model based on the Ostwald ripening mechanism were compared with the experimental data. The effect of solute availability, cooling rate and deoxidation practice on the particle population characteristics was determined. It was concluded that the amount, size and number of precipitating particles in Hadfield steel castings is possible to be controlled according to certain requirements by a careful selection of proper additives in proper amounts and also by the optimization of the casting process in aspects of deoxidation timing and control of the cooling rate of the castings.