Ivan Egry

Reference Data for the Density and Viscosity of Liquid Aluminum and Liquid Iron

The available experimental data for the density and viscosity of liquid aluminum and iron have been critically examined with the intention of establishing a density and a viscosity standard. All experimental data have been categorized into primary and secondary data according to the quality of measurement specified by a series of criteria. The proposed standard reference correlations for the density of the aluminum and iron are characterized by standard deviations of 0.65% and 0.77% at the 95% confidence level, respectively. The overall uncertainty in the absolute values of the density is estimated to be one of ±0.7% for aluminum and 0.8% for iron, which is worse than that of the most optimistic claims but recognizes the unexplained discrepancies between different methods. The standard reference correlations for the viscosity of aluminum and iron are characterized by standard deviations of 13.7% and 5.7% at the 95% confidence level, respectively. The uncertainty in the absolute values of the viscosity of the two metals is thought to be no larger than the scatter between measurements made with different techniques and so can be said to be ±14% in the case of aluminum and ±6% in the case of iron.

Reference Data for the Density and Viscosity of Liquid Copper and Liquid Tin

The available experimental data for the density and viscosity of liquid copper and tin have been critically examined with the intention of establishing a density and a viscosity standard. All experimental data have been categorized into primary and secondary data according to the quality of measurement specified by a series of criteria. The proposed standard reference correlations for the density of copper and tin are characterized by standard deviations of 1.3% and 1.0% at the 95% confidence level, respectively. The standard reference correlations for the viscosity of copper and tin are characterized by standard deviations of 6.3% and 20% at the 95% confidence level, respectively.

Surface tension measurement of molten silicon by the oscillating drop method using electromagnetic levitation

The surface tension of molten silicon was successfully measured by an oscillating drop method using electromagnetic levitation over a wide temperature range from 1100 to 1500°C including the undercooling condition of ΔT ≈ 300 K. Single crystals of silicon heavily doped with B and Sb (resistivity as low as 1 × 10−4 Ω·m) were successfully melted and levitated. The surface tension of molten silicon was 783.5 × 10−3 N/m at the melting point of 1410°C within the measurement accuracy of 3–4%; its temperature coefficient was −0.65 × 10−3 N/m·K. Secondary ion mass spectroscopy (SIMS) analysis showed that O and Sb evaporated during melting, while the B concentration after melting was unchanged. This means that surface tension and its measured temperature dependence correspond to those for a contamination-free silicon melt.

Surface tension of liquid metals and alloys — Recent developments

Surface tension measurements are a central task in the study of surfaces and interfaces. For liquid metals, they are complicated by the high temperatures and the consequently high reactivity characterising these melts. In particular, oxidation of the liquid surface in combination with evaporation phenomena requires a stringent control of the experimental conditions, and an appropriate theoretical treatment. Recently, much progress has been made on both sides. In addition to improving the conventional sessile drop technique, new containerless methods have been developed for surface tension measurements. This paper reviews the experimental progress made in the last few years, and the theoretical framework required for modelling and understanding the relevant physico-chemical surface phenomena.

VISCOSITY OF EUTECTIC PD78CU6SI16 MEASURED BY THE OSCILLATING DROP TECHNIQUE IN MICROGRAVITY

During the STS-83 Spacelab mission, a sample of Pd78Cu6Si16 was processed in the electromagnetic levitation facility TEMPUS. Surface oscillations of the levitated liquid droplet were excited, and frequency and damping of the oscillations were observed. Under microgravity conditions, the damping constant is simply related to the viscosity. This method was successfully applied. The experiments were performed in a temperature range of 400 K, including the eutectic temperature Te=1033 K. At this temperature, our data agree well with those of S. K. Lee, K. H. Tsang, and H. W. Kui [J. Appl. Phys. 70, 4842 (1991)].

Containerless Processing in Space—Thermophysical Property Measurements Using Electromagnetic Levitation

Electromagnetic levitation is a novel tool for measuring thermophysical properties of high-temperature metallic melts. Contamination by a crucible is avoided, and undercooling becomes possible. By exploiting the microgravity environment of an orbiting spacecraft, the positioning fields can be further reduced and undesired side effects of these fields can be minimized. After two successful Spacelab flights of the electromagnetic levitation facility TEMPUS, an advanced electromagnetic levitation facility is presently being studied for accommodation on the International Space Station, ISS. Due to the permanent nature of the ISS, an operational concept must be defined which allows the exchange of consumables without exchanging the entire facilty. This is accomplished by a modular design, which is presented. For all experiments, like measurement of specific heat, of surface tension and viscosity, of thermal expansion, and of electrical conductivity, noncontact diagnostic tools must be either improved or developed. Such tools are, for example, pyrometry, videography (high-speed and high-resolution), and inductive measurements. This paper summarizes the scientific results obtained so far and deduces some lessons learned that will be incorporated into the new design and will lead to both new results and a higher precision of the data.

Surface tension measurements on levitated liquid metal drops

Abstract An improved method to measure the surface tension of liquid metals is presented. It is shown that the application of digital image processing can increase the precision of measurements performed with the oscillating drop technique. In experiments on nickel, a good reproducibility of measured surface tension and agreement with literature data were found. Measurements on iron show evidence for an influence of the oscillation amplitudes on the measured values. Experimental results on Ni-10 at.% Ti seem to show an influence of oxygen as a surface active element on the surface tension of the pure alloy.

Density and atomic volume in liquid Al-Fe and Al-Ni binary alloys

Abstract The density of liquid Al – Fe and Al – Ni binary alloys have been determined over a wide temperature range by a non-contact technique combining electromagnetic levitation and optical dilatometry. The temperature and composition dependences of the density are analysed. A negative excess volume correlates with the negative enthalpy of mixing, compound forming ability and chemical short-range ordering in liquid Al – Fe and Al – Ni alloys.

X-ray diffraction study of undercooled molten silicon

The short-range order of molten silicon was investigated in a wide temperature range from 1893 K down to 1403 K, corresponding to an undercooling of 290 K. Energy-dispersive x-ray diffraction was used in combination with electromagnetic levitation. The structure factor and the pair correlation function were determined as a function of temperature from the experimental data. A small hump on the higher wave vector side of the first peak in the structure factor was observed at all temperatures. The position of the first peak in the pair distribution function shifted to shorter distances and its height increased gradually with decreasing temperature. No discontinuous behavior was observed in the entire temperature range investigated.

Density and excess volume of liquid copper, nickel, iron, and their binary alloys

Abstract The densities of liquid copper, nickel and iron and their binary alloys have been measured over a wide temperature range, including the undercooled regime. A non-contact technique was used, consisting of electromagnetic levitation and optical dilatometry. In all cases the density was a linear function of temperature. On the other hand, the concentration dependence was only linear for Fe–Ni, whereas Fe–Cu and Cu–Ni are characterized by a positive or negative excess volume respectively.