Microwave-sintering preparation and densification behavior of sodium zirconium phosphate ceramics with ZnO additive

Abstract

The dense NaZr2(PO4)3 (NZP) ceramics were successfully prepared by a microwave sintering process with x wt.% ZnO as a sintering aid (where x = 0, 0.5, 1.0, 2.0 and 3.0). The effects of ZnO additive on the crystal structure, microstructure and sintering behavior of as-prepared NZP ceramics were systematically investigated. The single NZP phase can be achieved in the wide temperature range of 900–1200 °C holding for 2 h by microwave-sintering technology. The addition of ZnO sintering aid would not noticeably change the crystal structure of NZP. Importantly, ZnO additive significantly promoted the densification and 1.0 wt% ZnO-added sample possessed the maximum relative density of 96.5% after sintering at 1100 °C, considerably higher than that of pure NZP sample. Besides, the Vickers hardness of the above sample could attain near 800 MPa, which is about four times as hard as the pure NZP ceramics without ZnO additive. It was suggested that the combination of microwave sintering with appropriate addition of ZnO sintering aid would provide a convenient and efficient method for rapid fabrication of dense NZP ceramics.