Microwave Sintering And Mechanical Properties Of La2o3/Nb2o5 Toughened Al2o3 Ceramics

To improve the toughness of Al2O3 ceramic, xLa(2)O(3)/10Nb(2)O(5)-(90-x)Al2O3 (x = 2.5-15.0 vol.%) composite ceramics were synthesized via microwave-sintering. The influences of sintering temperature (T-s) and La2O3 content on phase composition and mechanical property of xLa(2)O(3)/10Nb(2)O(5)-(90-x)Al2O3 composite ceramics were studied. It is shown in the results that the T-s of La2O3/Nb2O5 doped Al2O3 ceramic was 150 degrees C lower than that of Al2O3 ceramic. With the increase of x, La0.33NbO3, LaNbO4 and LaAl11O18 were formed successively. LaNbO4, columnar-Al2O3 grains and LaAl11O18 with plate-like shape were generated in-situ during the sintering period. Compared to Al2O3 ceramic, the fracture toughness of xLa(2)O(3)/10Nb(2)O(5)-(90-x)Al2O3 ceramics were at least 70% higher when 5.0 <= x <= 12.5. 7.5La(2)O(3)/10Nb(2)O(5)-82.5Al(2)O(3) ceramic exhibited superior mechanical property: Hv = 12.0 GPa, K-IC = 6.2 MPa.m(1/2) (1,500 degrees C, 30 min).