Synthesis and Characterization of Plasma Synthesized Nanostructured Magnesia-Yttria Based Nanocomposites
- PDF / 2,340,683 Bytes
- 12 Pages / 612 x 792 pts (letter) Page_size
- 65 Downloads / 135 Views
1056-HH08-44
Synthesis and Characterization of Plasma Synthesized Nanostructured Magnesia-Yttria Based Nanocomposites Jafar F. Al-Sharab, Rajendra Sadangi, Vijay Shukla, and Bernard Kear Materials Science and Engineering, Rutgers University, Piscataway, NJ, 08854 Keywords: Y2O3-MgO nanocomposite; powder synthesis; hot pressing; ceramic composite; mechanical and optical properties. Abstract Polycrystalline Y2O3 is the material of choice for IR applications since it has excellent optical properties in the visible, and near infra-red band. However, current processing methods yield polycrystalline Y2O3 with large grain size (> 100 µm), which limits the hardness and erosion resistance attainable. One way to improve strength is to develop an ultra-fine grained material with acceptable optical transmission properties. To realize a fine-grained ceramic, one approach is to develop a duplex-phase or composite structure, in which one phase inhibits the growth of the other phase during processing. In this study, Y2O3-MgO nanocomposite with various MgO content (20, 50 and 80 mol%) were synthesized using new plasma spray and flame synthesis techniques. Moreover, the mechanical and optical properties of a uniformly consolidated finegrained ceramic composite, comprising a 50:50 vol% mixture of Y2O3 and MgO, are measured and correlated with structure. Transmission Electron Microscopy imaging, as well as EDS chemical mapping, revealed that the consolidated sample have bi-continuous MgO-Y2O3 nanostructure with an average grain size of 200 nm. Introduction Future IR sensor materials are likely to be subjected to harsher mechanical and thermal environments than those that are used today. Sapphire (Al2O3) is the current material of choice for many technological applications, since it is readily available in high optical quality. A comprehensive review of commonly used IR sensor materials can be found in the literature [1,2]. While sapphire is currently among the best high strength MWIR transparent materials, it begins to exhibit optical absorption near 4.5 microns, resulting in signal loss at the 5 µm end of the MWIR band. In addition, sapphire loses strength above 600°C and is expensive to grow and process in single crystal form. Yttrium oxide (Y2O3-yttria) has excellent optical properties in visible, near IR and full 3-5 µm MWIR band. However, the current processing methods yield materials with >100 µm grain size [1] and inferior mechanical properties relative to that of sapphire. Increased strength can be achieved by reducing the grain size of the final sintered product to submicron range, while maintaining clean grain boundaries [3,4,5]. Over the last two decades, nanostructured materials have been the subject of intensive research worldwide, since exceptional mechanical and functional properties can be achieved [3,4,5]. Moreover, high-strain-rate superplasticity has been observed [6,7] in nanocomposite ceramics, which opens new opportunities for the near-net shape fabrication of such materials. Success in processing nanocomposites
Data Loading...
