This study aimed to investigate the influence of process parameters on crack formation in laser alloying or cladding of grey cast iron. For this purpose, the effects of laser power and feeding rate of Ni-based alloying powders were examined. The microstructure and hardness of the coating and the interface of the coating with cast iron (bonding zone) were studied. The results showed that the dilution ratio is crucial in crack formation, explaining the challenges in achieving a defect-free laser alloying coating on cast iron. The higher dilution ratio of laser alloying resulted in higher dissolved carbon and bigger (Nb, Ti)C carbides formation than in laser cladding coatings. In this study, cracks appeared in the coating due to the combination of the high amount of carbide in the layer and a sharp hardness gradient at the interface with the cast iron substrate. An empirical relation was proposed for dilution ratio as a function of specific energy density, which combined the most critical process parameters on crack formation.

Thermal conductivity is an important property for many iron cast components, and the lack of widely accepted thermal conductivity model for cast iron, especially grey cast iron, motivates the efforts in this research area. The present study contributes to understanding the effects alloy microstructure has on thermal conductivity. A thermal conductivity model for a pearlitic cast iron has been proposed, based on the as-cast alloy composition and microstructural parameters obtained at different solidification rates. According to the model, available parallel heat transfer paths formed by connected graphite flakes across eutectic cells are determined by the space between dendrite arms. The uncertainties both for model inputs and for validation measurements have been estimated. Sensitivity analysis has been conducted to result in better understanding of the model behaviour. The agreement between modelled and measured thermal conductivities has been achieved within 5% on the average for the investigated samples.

Thermal conductivity is an important property for cast components produced from different types of cast iron. Development of a general widely-accepted thermal conductivity model for compacted and lamellar graphite irons poses a research challenge. The present study extends the modeling approach introduced earlier for pearlitic lamellar graphite iron toward compacted graphite iron and ferritic lamellar graphite iron. The proposed thermal conductivity model of the bulk material is based on the alloy microstructure and Si segregation between eutectic cells and non-cell regions, at the main assumption that the heat paths in the eutectic cells are formed by connected graphite phases surrounded by ferrite phases. The overall thermal resistance of these heat paths is determined by the hydraulic diameter of the interdendritic region. The uncertainties both for the modeled and for experimentally derived thermal conductivities have been estimated. The importance of considering the Si segregation in the model has been discussed. For the investigated samples, the agreement between modeled and measured thermal conductivities has been achieved within 4% on the average, at the same value of the single fitting parameter found for pearlitic, pearlitic–ferritic lamellar, and compacted graphite iron alloys. The results contribute to the understanding of the material microstructure effects on the cast iron thermal conductivity.

The finite element three-dimensional transient model of the annealing process, including conductive and convective heat transfer in an aluminum (Al) coil was developed, implemented, and validated. It combines winding force dependent effective radial thermal conductivity model and the novel convective heat transfer modeling methodology. Experimental validation of the finite element model was performed for two industrial coils having different dimensions, strip thickness and crowning depth. The general agreement between the predicted and measured temperatures for most of the probes was better than 10% at the target material temperature. A series of measurements were configured and performed to supply both the input and validation data for the simulations. The effect of the additional wetted area on the convective heat transfer at the coil base was quantified. The guidelines on the virtual prototyping of the Al coil annealing process were provided, which can be of interest for the process designers.

Density and surface tension of liquid Ni-Cu-Fe alloys have been measured over a wide temperature range, including the undercooled regime. A non-contact technique was used, consisting of an electromagnetic levitator, an optical densitometer, and an oscillating drop tensiometer. 

At temperatures above and below the liquidus point, density and surface tension are linear functions of temperature. The concentration dependence of the density is significantly influenced by a third-order (ternary) parameter in the volume, while the surface tensions can be derived from the thermodynamic potentials (E)G of the binary phases alone.

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.

The density and surface tension of liquid Ni–Cu–Fe alloys have been measured over a wide temperature range, including the undercooled regime. A non-contact technique was used, consisting of an electromagnetic levitator equipped with facilities for optical densitometry and oscillating drop tensiometry. At temperatures above and below the liquidus point, the density and surface tension are linear functions of temperature. The concentration dependence of the density is significantly influenced by a third-order (ternary) parameter in the excess volume. The surface tensions are rather insensitive to substitution of the two transition metals Ni, Fe against each other and depend only on the copper concentration. By numerically solving the Butler equation, the surface tension of the ternary system can be derived from the thermodynamic potentials E G of the binary phases (Ni–Cu, Fe–Cu, Ni–Fe) alone.

Within the Integrated Project IMPRESS, funded by the EU, thermophysical properties of two Al-Ni alloys have been investigated: Raney-nickel (Al-31.5 at % Ni) and Al-25 at % Ni, corresponding to the intermetallic phase Al3Ni. Transition temperatures, latent heat, heat capacity, density and electrical resistivity were measured in the solid and liquid phases. In addition, surface tension and viscosity of the melts were also determined. All quantifies have been obtained as a function of temperature, in some eases also in the undercooled liquid. In this paper, we report on results obtained for the liquid phase using advanced container-based and containerless measurement methods. The obtained data yield a comprehensive characterisation of this technologically relevant class of alloys. 

Density and surface tension of liquid Cu–Fe–Ni alloys have been measured in an electromagnetic levitator over a wide temperature range, including the undercooled regime. Both properties are linear functions of temperature. Their concentration dependence, however, is highly non-linear. The fit of the density data requires an excess volume containing a substantial ternary contribution. The surface tension is correctly predicted by the Butler equation from the thermodynamic potentials of the binary phases alone. In addition, a simple model is proposed which describes the surface tension reasonably well and requires as input the surface tensions of the pure components only.

At two interfacial-tension measurement experiments with the same experimental conditions, steel samples and mold flux samples of the same compositions were melted in crucibles from the same batch. During the first experiment, the steel drop melted far below its liquidus and then was emulsified. At the second experiment, the steel melted at the expected temperature but did not emulsify. The difference that can be identified is the mass of the steel samples.

The agglomeration behaviour of reduced iron, made from magnetite powder by carbothermic reduction, was observed by using the in-situ X-ray transmission observation technique. The iron particles, above 1 mm, were clearly observed as black points. Further, the reduction speed was examined by using the thermogravimetric analysis. The bulk density of the packed powder layer and the grain size distribution of magnetite powder and carbon black powder were changed and the effects of them on the reduction speed and the agglomeration degree were examined. The agglomeration degree was evaluated with diameter of iron particles on the X-ray photographs, taken during heating, and the weight of collected iron particles after the observation experiments. Neither the bulk density of powder layer nor the grain size distribution of powder mixture affected to the reduction speed. The agglomeration degree decreased when the bulk density of the powder layer was increased by compacting. On the other hand, the agglomeration degree was increased when the grain size distribution of powder mixture was widened. Further, the height change of powder layer was also measured on the X-ray photographs and compared with the iron particles appearing behaviour to estimate the microscopic agglomeration behaviour. The mechanisms that grain size distribution affected the agglomeration degree were discussed.

Additive manufacturing is growing rapidly as a manufacturing method. Additive manufacturing is a rapid solidification process and may, as such, generate new microstructures with an improvement of mechanical properties compared to conventional manufacturing. The repeatability and deeper understanding of properties repeatability for both mechanical and thermophysical properties are not well-established. In the current study, a complete analysis of the nature of the anisotropy is experimentally analysed to provide input for better understanding of the printing process and the resulting properties as reliability and predictability are important factors to build trust in a new manufacturing process.

The thermo-physical and mechanical properties of Vibenite®60 was investigated in the as-manufactured, soft annealed and hardened state as well as after use in full scale high pressure die casting. Thermal conductivity in the as manufactured state was 23.3 to 27.5 W/mK in the temperature range from 25°C to 500°C. Annealing increased thermal conductivity to 25.0 up to 29.2 W/mK. Hardening reduced thermal conductivity of 19.8 to 26.1 W/mK. The tool wastested in production in the as fabricated state displayed a slight increase in thermal conductivity, which was interpreted as a slight tempering during use. Hardness measurements were made at room temperature and followed the same pattern as the thermo-physical properties. Rockwell and Vickers Hardness was lowest in the as lowest in the annealed state and hardest in the hardened state. Rockwell hardness was not affected by use in production while Vickers hardness decreased slightly.

Different modifications to the classical capillary model of penetration of liquid metals into porous refractories are presented; (1) with capillaries having different radii, (2) with zigzag capillaries, and (3) with capillaries, having periodically changing capillary radius along the path of penetration. All the modified capillary models were checked against our experimental results of measuring the penetration of liquid mercury into three types of alumina refractories, having different microstructure and pore size distribution. The maximum penetration height was measured by X-ray radiography, as a function of applied outside pressure. The model with periodically changing capillary has been found to describe the experimental data satisfactorily. This model divides the process of penetration into two stages. During the first period of “pre-penetration,” the maximum penetration height changes very slowly (but not linearly) as the outside pressure is increased in the interval between the “minimum threshold pressure” and the “maximum threshold pressure.” In the second, “bulk penetration” period, appearing above the maximum threshold pressure, the maximum height of penetration increases rapidly with outside pressure, according to the classical capillary model of penetration. The three structural model parameters of the model (minimum pore radius, maximum pore radius, and period of pore structure) were connected with the measured pore size distribution curves of the refractories through semiempirical equations. As a result, our complex semiempirical model is able to predict penetration diagrams for any inert liquid metal into any refractory of a similar type.

This paper investigates the effect of de-oxidation inclusions on micro-structure in low-carbon steels. Low carbon (0.07 wt%), high Mn (0.9 wt%) steel in a Al₂O₃ or MgO crucible was deoxidized by adding either aluminum (0.05 wt%) or titanium (0.05, 0.03 or 0.015 wt%) in a 400 g-scale vacuum furnace, and cast in a Cu mold at cooling rates between 2.0–6.0 K/s.The oxide inclusions were identified as Al₂O₃ (1–3 μm) in the Al-killed steel and Ti–Al–(Mg)–O (0.3–0.5 μm) in the Ti-killed steel. Oxide inclusion sizes in all the Ti-killed steels were smaller and inclusion densities higher than those in the Al-killed steel.Solidification structure, defined as the density of primary dendrite arms within a defined region was finer with increasing inclusion density and as a result, the solidification structure of the Ti-killed steel was finer than that of the Al-killed steel.A Confocal Scanning Laser Microscope (CSLM) and a Differential Scanning Calorimeter (DSC) were used to study the differences in solid state micro-structural evolution between the Ti-killed, Al-killed and the non de-oxidized samples. The growth of austenite grains were studied under isothermal conditions and it was found that both grain-boundary mobility and final grain size were lower in the Ti-killed sample than for the others. With regards to austenite decomposition, during continuous cooling from a comparable austenite grain structure, the resulting austenite decomposition structure was finer for the Ti-killed sample due to a higher Widmanstätten lath density due to precipitation at particles in addition to grain boundaries.

In semi-solid metal high pressure die casting and in conventional high pressure die casting, it is common to find a defect band just below the surface of the component. The formation of these bands is not fully understood. However, there are several theories as how they occur, and it has been suggested that segregation is caused by the migration of aluminium-rich externally solidified crystals. In the present work the formation of these bands is investigated theoretically by reviewing suitable potential mechanisms for the migration of such crystals. Two mechanisms are identified as the most probable: Saffman lift force and the Mukai-Lin-Laplace effect. However, it was not possible to identify which of these two mechanisms acted in the case studies. Further testing is required to identify the mechanism that is causing the migration of the aluminium globules and suitable tests are proposed. 

For the optimisation of the annealing process of aluminium coils, simulation of the process is often performed. To simulate the process with higher accuracy, reliable input parameters are required, and thermal conductivity (thermal contact conductance) is one of them. In the present study, a method to measure the thermal conductivity and thermal contact conductance of metallic sheets were developed based on the steady-state comparative longitudinal heat flow. The apparatus was built with a compression test machine, and thus it allows to control the pressure to the sample and carry out the measurements at different contact pressure. An equipped heater allows to heat the sample to 573 K. To evaluate the thermal conductance at the interface, a thermal resistance network model was applied. The measurements were carried out with an aluminium alloy (AA3003 sheets). In addition to the thermal contact conductance measurements, the surface roughness of the sheets was also investigated. The semi-empirical equation for the relationship between thermal contact conductance and contact pressure was obtained based on the measurement results.

In order to investigate the influence of the surface-active element on the interfacial phenomena between molten iron and molten Al2O3-CaO-SiO2 slag, a mildly surface-active element, nitrogen, was introduced, and the interfacial phenomena were directly observed using an X-ray sessile drop method. The multiphysics model was employed to calculate the velocity of the Marangoni convection caused by the surface/interfacial tension gradient along with the contour of the sessile drop. Movement of the sessile drop was observed in the experiment, and the driving force of the movement was discussed from the distribution of surface tension active element viewpoint. The calculated velocity of the Marangoni convection in the droplet was reasonably agreed with the literature data for the metal-gas system, and thus, the same model was applied for the metal-slag system. The velocity of the Marangoni convection for the metal-slag system becomes ten times lower compared to that of metal-gas system.

An evaluation method for the initial penetration of molten cast iron into the sand mold was suggested based on the laboratory-scale penetration experiments for the cast iron. The horizontal penetration depth of the molten cast iron into the sand core was analyzed using the capillary model. The early stage of the penetration was discussed, and it was clarified that the penetration is not stopped by the solidification but is stopped by the decreasing of the equivalent pore radius. It was explained that the equivalent pore radius decreases with increasing the penetration depth, and the penetration is stopped when the critical pressure, i.e., the pressure required for the penetration, becomes higher than the pressure which is acting on the penetration front. Based on the analysis, an evaluation method of the penetration of depth at the early stage of the penetration was suggested. The analysis method was applied for the other type of metals (mercury and steel) as well, and reasonable results were obtained. A simplified finite-element model of liquid iron penetration into a sand core was developed, accounting for heat exchange between the melt and the porous medium, at different pore geometries.

The thermal diffusivities of some industrially important alloys have been measured as a part of the EU funded Intermetallic Materials Processing in Relation to Earth and Space Solidification (IMPRESS) project which is coordinated by the European Space Agency (ESA). The thermal diffusivities of the alloys were measured by the Laser flash method with a carefully designed gas cleaning system to remove traces of oxygen from the argon atmosphere. In the present work, the thermal diffusivity of TiAlNb (Ti46.1Al45.9Nb8 at %) and AlNi alloy (Al-Ni31.5 at %) alloys have been measured independently at Royal Institute of Technology, Sweden (KTH) and National Physical Laboratory, UK (NPL). The results from both laboratories were consistent, and have been compared with predictions of phase transformation temperatures calculated using Thermo Calc and MTDATA software. Generally the variation of thermal diffusivity appears to be related to the phase transformation. However, one anomaly observed in the present work on TiAlNb was a maximum thermal diffusivity value at about 1100K. No corresponding peak was found for the density, ρ, the specific heat capacity, Cp, or the electrical resistivity, 1/σ, which were also measured as part of the project. In view of the fact that the thermal diffusivity could be related to electrical conductivity by the Wiedemann-Franz law describing electronic contribution to heat conduction, the present results indicate a non-electron contribution. This aspect is being currently investigated further. The recommended thermal diffusivity value of TiAlNb and AlNi alloys were obtained as follows. TiAlNb alloy: α = 3.75+ 5.16 ·10-3T+1.89·10-6 T2 – 2.69·10-9 T3 [10-6 m2 s-1] (293 K < T < 1573 K) AlNi alloy: α = 4.77+ 5.41·10-2T – 7.14·10-5T2 + 2.88·10-8T3 [10-6 m2 / s] (373K

The aim of the present study is to elucidate the influence of individual microstructural parameters, such as pearlite fraction, nodularity, and eutectic cell size, on the tensile strength (UTS) of cast irons. The UTS model was built by integrating the rule of mixtures for each microstructural component, and the UTS was described as a function of the aforementioned factors. The UTS and the required microstructure parameters for the model calculation were obtained experimentally. In the model, two coefficients were introduced to quantify the influence of the eutectic cell size and the interaction terms for the mixed two components. These coefficients were determined through fitting the experimental data, and the model's accuracy was validated using data not included in the fitting process. The results exhibited reasonable agreement, confirming the model's reliability. The model, thus, offers insights into the influence of each microstructural factor on UTS and serves as a guide for designing alloys to achieve the desired UTS through microstructure modifications.

The primary objective of this study is to explore the impact of temperature and magnesium addition on the partial oxygen potential in lamellar, compacted, and spheroidal cast irons during the cooling process. The oxygen potential is assessed in large-scale plant trials with a 1000 kg scale. Thermodynamic calculations are conducted, and the results are compared with the experimental values. There is a reasonable agreement between the experimental and calculated values, facilitating the prediction of oxygen potential in temperature ranges where measurements are challenging. According to the thermodynamic calculations, it is observed that varying amounts of added magnesium result in the formation of different types of inclusions during cooling. This, in turn, influences the temperature dependency of the oxygen potential in the molten metal.

In this paper, measurements of the heat capacities and thermal diffusivities of commercial CMSX-4 nickel-based superalloy are described, and the results are presented. Since the as-received commercial alloy sample is not at the thermodynamic equilibrium state, the phases present in the alloy undergo transformations toward equilibrium state as the measurements are made at temperatures above which the rate of transformation can be significant. The microstructures of the as-received sample as well as heat treated samples were observed, and the relation with the properties was discussed. The results are discussed considering the phase changes occurring with the thermodynamic equilibrium state as the reference. The results are of great relevance in the performance of these alloys in industrial applications.

The thermal expansion and density of Compacted Graphite Iron (CGI) and Spheroidal Graphite Iron (SGI) were measured in the temperature range of 25–500 °C using push-rod type dilatometer. The coefficient of the thermal expansion (CTE) of cast iron can be expressed by the following equation: CTE = 1.38 × 10−5 + 5.38 × 10−8 N − 5.85 × 10−7 G + 1.85 × 10−8 T − 2.41 × 10−6 RP/F − 1.28 × 10−8 NG − 2.97 × 10−7 GRP/F + 4.65 × 10−9 TRP/F + 1.08 × 10−7 G2 − 4.80 × 10−11 T2 (N: Nodularity, G: Area fraction of graphite (%), T: Temperature (°C), RP/F: Pearlite/Ferrite ratio in the matrix).

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.

Surface tensions of low carbon slabs and 16 mass%Cr stainless steel were estimated using a surface thermodynamic model proposed by Mukai et al. As an application of the model, an index to evaluate the driving force for the fine bubble entrapment by the solidifying shell, the Mukai-value, M, was calculated from the surface tension values. The relationship between Mukai-value and number of entrapped bubbles was discussed. A linear relationship was found between the number of captured bubbles and Mukai-value. In the previous work, the Mukai-value was used as a relative scale to evaluate the driving force for the movement of bubbles. However, by calculating the M from the surface tension values by the surface thermodynamic model, physically reasonable Mukai-values could be obtained.

The specific heat and thermal diffusivity of Compacted Graphite Iron (CGI) and Spheroidal Graphite Iron (SGI) were measured at temperatures ranging between 373 and 773 K (100 and 500 °C) using differential scanning calorimetry (DSC) and between 298 and 773 K (25 and 500 °C) using the laser flash method, respectively. Specific heat increased with increasing amounts of graphite and pearlite, as well as with Si content. As a recommended value of the specific heat for fully ferritic high-silicon SGI, the following relation was suggested:(Formula presented.) where T is the temperature in Celsius, (Formula presented.) is the mass% of Si, and fg is the area fraction of graphite (%). The thermal diffusivity of cast irons tends to increase with increasing amounts of graphite, and decrease with greater nodularity. It was found that nodularity had a strong influence on thermal diffusivity in the nodularity range of 15–30%. 

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. 

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), specific heatcapacity, thermal diffusivity, surface tension andviscosity of one Fe-Cr and of a low oxygen eutectoidmanganese steel are reported. In addition to the groundbased experiments, parabolic flights (microgravity)experiments with a non-contact electromagneticlevitation device were employed for surface tension andviscosity measurements.

Accurate kinetic parameters are vital for quantifying the effect of binder decomposition on the complex phenomena occurring during the casting process. Commercial casting simulation tools often use simplified kinetic parameters that do not comprise the complex multiple reactions and their effect on gas generation in the sand core. The present work uses experimental thermal analysis techniques such as Thermogravimetry (TG) and Differential thermal analysis (DTA) to determine the kinetic parameters via approximating the entire reaction during the decomposition by multiple first-order apparent reactions. The TG and DTA results reveal a multi-stage and exothermic decomposition process in the binder degradation. The pressure build-up in cores/molds when using the obtained multi-reaction kinetic model is compared with the earlier approach of using an average model. The results indicate that pressure in the mold/core with the multi-reaction approach is estimated to be significantly higher. These results underscore the importance of precise kinetic parameters for simulating binder decomposition in casting processes.

In the present work, the interfacial reactions between molten synthetic slag (Al2O3–CaO–SiO2–FeO) and liquid iron alloy were investigated at 1873 K with the aid of an X‐ray radiographic apparatus. The mother slag consists of 40 mass%CaO, 40 mass%SiO2 and 20 mass%Al2O3. FeO was added to this slag at the experimental temperature, and the movement of the droplet and deformation of the droplet shape were monitored in the dynamic mode. The change of the shape of the droplet is discussed based on the reaction and mass transfer at the slag/metal interface. From the movement of the droplet, interfacial velocity of the metal droplet induced by Marangoni flow was estimated and compared with the results obtained in the present laboratory earlier. The importance of surface velocity values on steel refining process simulations is discussed.

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.

The objective of the present study is to evaluate the hot tearing tendency based on the Clyne and Davies model by evaluating the critical times which can be obtained using a newly developed method. A method to determine the critical times required to calculate the crack susceptibility was presented based on the measurement results with Al–Si alloys, and the method to calculate the crack susceptibility coefficient was presented. In the newly developed method named “Signal intensity method,” signals were generated by tapping the edge of a waveguide which is immersed in molten and solidifying sample and the critical solid fractions were obtained from the signal intensity change. The conventional thermal analysis was also performed simultaneously and the corresponding critical points were identified. The method shown in the present study will enable the determination of the crack susceptibility coefficient with higher accuracy.

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 FactSage^TM6.2. As the models can only predict viscosities for a solid free melt, obtained values by FactSage^TM6.2 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 FactSage^TM6.2 calculations, the viscosity of the solid containing slag increases from 2.1 to 5.5 poise at the industrial operating temperature (∼1250°C).

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.

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 thermooptical 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 FactSage^TM6.2 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.

A formula is derived to describe the surface tensions of binary and dilute multicomponent alloys such as iron alloys. It was thermodynamically proved that the surface tension can be described by a function of the concentrations of the alloy components in bulk phase through the use of thermodynamic parameters. The formula was applied to the binary alloys, Fe-O-N and Fe-O-S systems. The described surface tensions were found to be in good agreement with the measured values.

Some ideas for promoting the metal separation process are proposed based on the consideration of the force caused by interfacial tension gradient as a driving force. The force drives the particle toward the direction of the lower interfacial tension side, which has been confirmed by water model experiments. Therefore, it is possible to move fine metal particles by producing interfacial tension gradient between fine metal particles and molten slag. The force in molten slag–metal (iron) system was evaluated under some assumptions. The evaluation indicates that the force is enough large to engulf the fine metal particle by the interface between metal particle and slag for promoting metal separation process.

The surface tension, density, and viscosity of the Ni-based superalloy CMSX-4® have been determined in the temperature ranges of 1,650–1,850 K, 1,650–1,950 K, and 1,623–1,800 K, respectively. Each property has been measured in parallel by different techniques at different participating laboratories, and the results are compared with the aim to improve the reliability of data and to identify recommended values. The following relationships have been proposed: density-ρ (T) [kg· m−3] = 7,876 − 1.23(T − 1,654 K); surface tension-γ (T) [mN·m−1] = 1,773 − 0.56 (T − 1, 654 K); viscosity-η (T) [mPa·s] = 8.36 − 1.82 × 10−2(T − 1,654 K). For a comparison, surface-tension measurements on the Al-88.6 at% Ni liquid alloy with the same Al-content as the CMSX-4® alloy were also performed. In addition, the surface tension and density have been theoretically evaluated by different models, and subsequently compared with new experimental data as well as with those reported in the literature. The surface-tension experimental data for the liquid CMSX-4® alloy were found to be close to that of the Al-88.6 at% Ni alloy which is consistent with results from the compound formation model (CFM).

Viscosity measurements for SiO2-CaO-Al2O3 based ternary slags with low SiO2 content were performed for a wide temperature range utilizing the aerodynamic levitation and rotating bob methods. Aerodynamic levitation was used for temperatures >= 2229 K and the viscosity was calculated by the sample oscillation decay time. The rotating bob method was used for temperatures <= 1898 K and the viscosity was determined by the variation of the torque at different rotation speeds. Fitting curves were created using Mauro’s viscosity equation. The main sources of systematic error were identified to be the sample weight measurement, the resolution of the high-speed camera, the fitting of the linear trend line in the torque against rpm diagrams and the vertical position of the bob. The combined standard uncertainty from all error sources was calculated for both measurement methods.

The viscosity of low SiO2 (10–20 mass%)-CaO-Al2O3 slag system was measured in a wide temperature range (1 623–2 800 K) using the rotational bob method and the aerodynamic levitation method. The influence of SiO2/Al2O3 ratio and CaO/Al2O3 ratio on the viscosity was examined. It was concluded that the SiO2/Al2O3 ratio did not affect the degree of polymerization of the aluminosilicate network in the composition range of the present study. An abnormal behaviour of the viscosity was observed at a CaO/Al2O3 ratio of 1.57 which was attributed to the formation of 12CaO·7Al2O3-like clusters. It was concluded that the overall influence on the viscosity could be expressed as the summation of the influence from the aluminosilicate network and the influence from the cluster formation of the primary precipitating solid phase. The temperature dependence of the cluster formation was coupled to the driving force of precipitation of the 12CaO·7Al2O3 phase.