Preparation and mechanical properties of NiCr–Al2O3–ZrO2(8Y) ceramic composites

The mechanical properties of the 8 mol% yttria stabilized zirconia (8YSZ), as a promising anodic material for solid oxide fuel cell, should be improved to increase its reliability and service life. NiCr–Al2O3–ZrO2(8Y) ceramic composites were successfully fabricated by pressureless sintering in the carbothermal protecting atmosphere, and the mechanical properties and microstructure were investigated as well. The results showed that 8YSZ matrix composites had good mechanical properties due to the NiCr alloy and α-Al2O3 secondary phases. The bending strength and fracture toughness could reach at a range of 224–300 MPa, 3.8–4.6 MPa m1/2, respectively, when 0–12 vol.% of NiCr alloy and 10 vol.% alumina particles were added into 8YSZ ceramic. 10 vol.% α-Al2O3 obviously enhanced the densification of the 8YSZ ceramic.

► Pressureless sintering method and carbothermal protecting atmosphere were adopted.
► Adding 0–12 vol.% NiCr alloy and 10 vol.% alumina can boost properties of 8YSZ ceramic.
► Fracture toughness of 8YSZ-based composite reached a maximum value of 4.6 MPa m1/2.
► NiCr alloy and α-Al2O3 located at the ZrO2 grain boundaries or triple junctions.