Yttria-Coated Tungsten Fibers for Use in Tungsten Fiber-Reinforced Composites: A Comparative Study on PVD vs. CVD Routes

Tungsten fiber-reinforced tungsten (Wf/W) composites are being developed to improve the intrinsic brittleness of tungsten. In these composites, engineered fiber/matrix interfaces are crucial in order to realize toughening mechanisms. For such a purpose, yttria (Y2O3), being one of the suitable interface materials, could be realized through different coating techniques. In this study, the deposition of thin films of yttria on a 150 µm tungsten wire by physical and chemical vapor deposition (PVD and CVD) techniques is comparatively investigated. Although fabrication of yttria is feasible through both CVD and PVD routes, certain coating conditions such as temperature, growth rate, oxidation of Wf, etc., decide the qualitative nature of a coating to a particular extent. In the case of PVD, the oxidation of Wf is highly reduced compared to the WO3 formation in high-temperature CVD coating processes. Yttria-coated tungsten fibers are examined comprehensively to characterize their microstructure, phase, and chemical composition using SEM, XRD, and Raman spectroscopy techniques, respectively.

Development of a Lightweight Tungsten Shielding Fiber That Can Be Used for Improving the Performance of Medical Radiation Shields

Radiation exposure in medical institutions is mainly due to low doses. Low-dose radiation mainly means scattered radiation, and such scattered radiation can be shielded with a lightweight shielding suit. In this study, the shielding performance of shielding fabrics woven by winding polyethylene (PE) yarn around a 30 μm tungsten wire was evaluated. To improve the shielding performance, an air pressure dispersion process of coating tungsten nanopowder on the fiber was developed. The radiation shielding effectiveness of the shielding fibers with and without dispersed tungsten nanopowder were compared by measuring the spatial dose inside the diagnostic X-ray imaging room of a medical institution. The results of the experiment confirmed that the fabric coated with tungsten nanopowder improved the shielding performance of the general tungsten fiber by approximately 15% and provided relatively effective low-dose radiation shielding at approximately 1.2 m of the X-ray imaging equipment. This study shows that tungsten fiber can be helpful in manufacturing lightweight shielding clothing for protection from scattered radiation in medical institutions.