Viscosity Of Mold Flux Research Articles

Effects of Li<sub>2</sub>O on Properties of Low Fluoride Content Mould Flux for High Speed Continuous Casting

In order to reduce fluorine pollution, partial fluoride could be replaced by Li2O in mould flux. The effects of Li2O on properties of low fluoride content mould flux for high speed continuous casting were studied. The properties included melting temperature, viscosity, fluidity, surface tension and Al2O3 inclusion adsorption. The results showed that with the increase of Li2O content, melting temperature and viscosity of mould flux decreased obviously, fluidity increased, surface tension changed little, and Al2O3 inclusion adsorption of mould flux increased. In order to play an effective role, the appropriate Li2O content should be less than 4 per cent. The crystallization state of mould flux changed after slag adsorbed Al2O3. There were some small cuspidine and wollastonite crystals in the sample.

Effects of TiO<sub>2</sub> on the Viscocity and Solidification Temperature of Mold Fluxes for the Stainless Steel

Effects of TiO2 on the viscous characteristic of mold fluxes for the stainless steel were investigated by the rotary viscometer, TEM and XRD. The results showed that with the increasing amount of additive TiO2, the viscosity and solidification temperature of mold fluxes could decrease gradually, and then increase rapidly. The viscosity and solidification temperature of mold fluxes were minimum of 0.30Pa.s (1300°С ) and 1198°С respectively, as amount of additive TiO2 was 10mass%. The viscosity of mold fluxes could be decreased by the additive TiO2 which played the role of network modifier, and could be increased by the precipitation of perovskite (CaTiO3) crystals as amount of additive TiO2 was more than the critical value. The growth of cuspidine and wollastonite crystals could be restrained, and the precipitation of perovskite and melilite crystals could be promoted by the additive TiO2. In this study, the solubility of additive TiO2 was more than 20mass% in mold fluxes at 1350°С .

Comparison of properties of mould powders with identical chemical composition produced from different raw materials

An investigation was carried out to clarify the effect of the chemical composition of mould powder on its properties. A suitable commercial mould powder used for casting of some alloy steels was analysed. Ten different powders were designed to have identical elemental chemical composition but with some different phases using different raw material sources. These 11 powders were fired to 1300°C for 1 h. X-ray diffraction (XRD) analysis indicated that main phases are essentially the same. Prediction of mould flux viscosity by viscosity models yields identical values for all specimens. Melting rate was calculated for all samples and resulted similar values. With the same particle size range, bulk density of all powders was almost the same. The properties of the samples were similar and all with very good lubrication behaviour. It was concluded that the role of elemental chemical analysis in mould powders is more important than phase analysis and the raw materials used. This offers the opportunity for using 'waste' products as sources of raw materials for mould powders.

Evaluation of Viscosity of Mold Flux by Using Neural Network Computation

A new estimation method of viscosity or solidification temperature of mold fluxes was proposed by applying the neural network computation. In this evaluation system, the viscosity and the solidification temperature of mold fluxes can be evaluated from the analytical compositions in multi-component systems of SiO2–Al2O3–CaO–MgO–Na2O–F–T.Fe–ZrO2–TiO2–BaO–MnO–B2O3–S–C without any conversion of S or F to sulphide or fluoride. It was found that the calculated results of the dependence of viscosity on temperature and composition agree with the experimental results more precisely than some conventional physical models for viscosity. Furthermore, viscosity of mold fluxes can be estimated precisely in the wide range of SiO2 content.

Cold Model Experiment on Infiltration of Mould Flux in Continuous Casting of Steel: Simple Analysis Neglecting Mould Oscillation

A new cold model of continuous casting is developed to clarify the infiltration of mould flux into channel between a mould and a solidifying shell. In the experiment, silicone oil is poured and infiltrated down into the channel between an acrylic plate and a moving belt. In contrast with most of the previous analyses that assumed a fixed thickness of the liquid flux film, this model is based on an idea that the thickness can be varied depending on the balance of forces acting on the shell: static pressure in the molten steel pool, and dynamic and static pressure in the mould flux channel. Furthermore, a linear gauge sensor that is in contact with the acrylic plate monitors the film thickness of oil, while in continuous casting the thickness of mould flux cannot be measured during the operation.Simple experiments without oscillating motion clearly reveal that the infiltration behavior is largely dependent on the profile of channel: In the channel that becomes narrower in downward direction, the infiltration of oil is enhanced with the increase of both belt velocity and oil viscosity. In contrast, for the channel that becomes wider along the downward direction, the increase of the velocity and the viscosity reduces the oil infiltration.In continuous casting operation, the increase of both casting velocity and viscosity of mould flux decreases the mould flux consumption. Those observations indicate that the infiltration of mould flux is strongly governed by the channel that becomes wider in casting direction.

Effect of alumina pickup on mould flux viscosity in continuous slab casting

Mould flux samples were taken from a continuous slab caster mould at various stages during casting sequences. These confirmed that the amount of alumina pickup reaches a steady state level within the first 40 min of casting (in agreement with a simple model of alumina pickup). The steady state level was 3–4 mass-% higher than the original alumina content of the flux. Viscosity measurements carried out on two commercial mould fluxes, with different levels of alumina added, showed that the viscosity increase as a result of a 4 mass-%increase in alumina is not likely to affect mould behaviour. Comparison of the measured viscosities with predictions from literature models showed that no single literature model corresponds consistently to the measured values.