[OASIS-ELF]
Oxygen Analysis for Enhanced Utilization of the ISS-ELF via Surface Tension Measurements

RESEARCH OVERVIEW

• Metals are often melted during manufacturing, but their properties at high temperatures are difficult to measure accurately on Earth.
• On Earth, containerless methods eliminate contamination from crucibles; however, gravity still affects the results, requiring correction models.
• In space, gravity effects are removed, allowing more reliable measurements of essential properties such as density, surface tension, and viscosity.
• Oxygen Analysis for Enhanced Utilization of the ISS-ELF via Surface Tension Measurements (OASIS-ELF) uses platinum, which is not strongly affected by oxygen, as a reference material for accurate measurements.
• It also studies molten zirconium to understand how oxygen changes its properties.
• The data enhances the accuracy of ground experiments, support improved industrial processes such as welding and casting, aid in the development of new materials, and help optimize manufacturing processes.
• These advances also contribute to energy efficiency, reduced CO₂ emissions, and environmental sustainability.

DESCRIPTION

Accurate values of density, surface tension, and viscosity are crucial for understanding and optimizing high-temperature melt processes, including casting, welding, and additive manufacturing. On Earth, containerless methods are employed to avoid contamination from crucibles. However, even with containerless techniques, measurements are still influenced by gravity, and correction models are necessary to interpret the data accurately.

In a microgravity environment, the influence of gravity-induced deformation is eliminated, allowing more direct and reliable determination of thermophysical properties. Nevertheless, previous space-based measurements often neglected the effects of oxygen dissolution into the bulk and oxygen adsorption at the melt surface, both of which significantly alter the measured values.

Oxygen Analysis for Enhanced Utilization of the ISS-ELF via Surface Tension Measurements (OASIS-ELF) addresses these limitations by conducting experiments on the International Space Station. Using the Electrostatic Levitation Furnace, accurate measurements of density, surface tension, and viscosity are obtained for molten platinum, which is selected as a reference material because it is scarcely affected by oxygen and thus serves as a benchmark for oxygen-free conditions. Additionally, measurements are conducted on molten zirconium, with a focus on quantitatively evaluating the influence of oxygen on its thermophysical properties.

The resulting data provides a benchmark for validating ground-based correction methods, improving the accuracy and reliability of terrestrial measurements. Ultimately, these advances support the optimization of industrial processes such as casting and welding, facilitate the development of new high-performance materials, and contribute to energy efficiency, reduced CO₂ emissions, and sustainable industrial development.

SPACE APPLICATIONS

By better understanding the how molten metals behave in a space environment could inform manufacturing efforts for future Moon and Mars expeditions, where resupply missions from Earth are not readily available.

EARTH APPLICATIONS

The obtained data contributes to the optimization of industrial high-temperature melt processes such as casting and welding, as well as the development of new materials, thereby promoting energy efficiency, reducing CO₂ emissions, and ultimately supporting sustainable development.

OPERATIONAL REQUIREMENTS AND PROTOCOLS

The investigation is performed using the Electrostatic Levitation Furnace (ELF) inside the Kibo module of the International Space Station. Metallic samples of platinum and zirconium, approximately 2 mm in diameter, are levitated, melted, and oscillated to measure density, surface tension, and viscosity. Each sample is processed multiple times under controlled gas conditions to evaluate both oxygen-free and oxygen-affected properties. High-speed video and pyrometer data is recorded and downlinked for analysis on the ground. Postflight sample return is required to analyze the oxygen content after the experiments on Earth. Each experimental run is expected to take approximately 60 minutes, and more than 10 observations are planned during the increment.

OZAWA Shumpei [Chiba Institute of Technology]