High density BaCeO 3 ceramics sin tered using microwave irradiation
- PDF / 4,378,400 Bytes
- 7 Pages / 595 x 842 pts (A4) Page_size
- 12 Downloads / 196 Views
0906-HH01-04.1
High density BaCeO3 ceramics sintered using microwave irradiation A. S. Vanetsev1, A. V. Orlov2 and Yu. D. Tretyakov2 1
Chemical Synergy Laboratory, Kurnakov Institute Of General and Inorganic
Chemistry RAS, Russian Federation, Moscow, 119991, Leninskii ave. 31. E-mail: [email protected]. 2
Department of Materials Science, Lomonosov Moscow State University,
Russian Federation, Moscow, 119992, Leninskie Gory.
INTRODUCTION Recent investigations of the barrier properties of various materials showed that ceramics based on BaMO3 (M = Zr, Hf, Ce) phases have the highest resistance against Y(R)–Ba cuprate melts, which are used in the syntheses of high-Tc superconductors [1, 2]. However, conventional ceramic technology requires longterm anneals at temperatures above 1500°C to manufacture high-density ceramics based on the aforementioned compounds. Therefore, it is important to develop new sintering techniques with lower sintering temperatures and shorter times. Microwave processing offers a means to solve this problem. Several studies [3, 4] demonstrated the efficiency of microwave sintering in manufacture of oxide and non-oxide ceramics. It is noteworthy that microwave-sintered ceramics have far smaller grain sizes than the analogous ceramics manufactured by conventional thermal processing and possess better mechanical properties. Therefore, we expect ceramics sintered in microwave and thermal fields to significantly differ in their functional properties (mechanical strength, corrosion resistance, and electrophysical properties). Thus, microwave processing not only consumes less energy than thermal processing but also can improve the functional parameters of sintered ceramics. The goal of this work was to investigate the capabilities of high-power microwaves in manufacture of small-grained barium cerate ceramics.
0906-HH01-04.2
EXPERIMENTAL The barium cerate sample was prepared by oxalate coprecipitation. Aqueous solutions of barium and cerium nitrates in an equivalent proportion were added to a water–ethanol (4:1) solution of ammonium oxalate at 80°C . The precipitate was filtered off and dried in air. The resulting precursors were sintered in air at 1000°C for 6 h. The phase composition of the oxide powders was monitored using X-ray powder diffraction (DRON-3M, Cu Kα irradiation). The powders were milled in isopropanol for 30 min in Fritsch Pulverisette ball-mill. Aqueous polyvinyl alcohol (PVA) was added during milling to plasticize the powder (1 wt % PVA/oxide). In addition, 1 wt % CuO was added as a flux to enhance the sintering [5]. The powders were compacted using Carver hydraulic press. The compacted samples were preannealed at 500oC for 6 hours to remove the PVA binder. The microwave sintering was carried out in a MultiLab 2.5 furnace (output power – 2.4 kW; frequency – 2.45 GHz). Note that the absorptivity of BaMO3 phases at room temperature is very low. In view of this, we used hybrid microwave heating, a method widely applied to the microwave processing of weakly absorbing compo
Data Loading...
