Structural and physical properties of porous Alumina toughned zirconia composite manufacturing by graphite additives

Alumina Toughened Zirconia (ATZ) composite with (10 and 20) Wt.% alumina have been prepared through powder compaction method. Graphite additives (0,10,20,30 and 40) wt % have been added as a pore former to produce porous ATZ. The composite were sintered in air at 1500 °C for 2hrs. Porosity effect on physical and structural properties have been investigated. Porosity and bulk density were measured using Archimedes method. The results showed that porosity increased and bulk density decreased with graphite additives increases in range (9.09-53)% and (5-2.5)g/cm3 for (3Y-TZP/10 Wt.%Al2O3) specimens, also in range (7.4-51.6)% and(5.5-2.7)g/cm3 for (3Y-TZP/20 Wt.%Al2O3) specimens. By using X-ray diffraction, phase content and (t-ZrO2) retention were detected. The results showed that the intensity of (t-ZrO2) phase decreased with increasing porosity, the crystallite size increased from (25.8 to 35.1)nm for specimens containing(3Y-TZP/10Wt.% Al2O3) and from (34.2-40.2)nm for specimens containing (3Y-TZP/20Wt.%Al2O3),while the lattice strain decreased from (0.14-0.10)×10-2 for specimens containing(3Y-Tzp/10w%tAl2O3) and from (0.10-0.08)×10-2 for specimens containing(3Y-TZP/20Wt.%Al2O3). Surface morphology detected by atomic force microscope (AFM). The average grain size and roughness for (3y-TZP/10Wt.%Al2O3), (3Y-TZP/20Wt.%Al2O3) specimens increased with increasing porosity (83.8-100.6) nm and (9.8-32.7), (69.5-94.8) nm and (1.1-28.9) respectively. while the lattice strain for (3y-TZP/10Wt.%Al2O3) and (3Y-TZP/20Wt.%Al2O3) decreased with increasing porosity (11.7-37.8) and (6.5-34.1)nm respectively. It was found that porous ATZ was successfully fabricated by using graphite additives. The total porosity of (3Y-TZP/Al2O3) composite after sintering can be generally controlled by the nominal graphite content in the powder mixture. The porosity strongly influenced on physical and microstructural properties.