Effect of porosity on hardness of Al2O3–Y3Al5O12 ceramic composite

•Al2O3 doped with different Y2O3 contents sintered at 1600 °C—2 h•Al2O3–YAG ceramic composites with hardness higher 1000 HV•Hardness on different porosities presents exponential behavior.•Pre-exponential constants for hardness increase with Y2O3 content varying of 4.0 and 6.5 for compositions containing 20 wt.% and 36.5 wt.% Y2O3, respectively.

In this work, the effect of porosity on hardness of Al2O3–Y3Al5O12 (YAG) ceramic composites was investigated. Al2O3 powders containing 20 wt.% and 36.5 wt.% of Y2O3, were mixed, compacted by cold uniaxial pressing at different pressures ranging from 40 MPa to 100 MPa, and subsequently sintered at 1600 °C for 2 h. The sintered samples were characterized by X-ray diffraction, presenting α-Al2O3 and Y3Al5O12 as crystalline phases. Samples with relative densities ranging from 78 to 80% and 87 to 91% were obtained depending on the composition and the compaction pressure used. The hardness values obtained were between 1010–1080 HV and 370–470 HV, for mixes of Al2O3–Y2O3 having the composition levels of 20 wt.% and 36.5 wt.% Y2O3, respectively. The hardness was examined using classic exponential rule with pre-exponential constants which simulate the effect of porosity on the hardness of the sintered samples. These pre-exponential constants were identified to be 4.0 and 6.5 for compositions containing 20 wt.% and 36.5 wt.% Y2O3, respectively.