DEVELOPMENT OF ZIRCONIA TOUGHENED ALUMINA CEREMIC NANO COMPOSITES WITH ADDITION OF AND CNTs

Abstract

Composites are a class of materials developed by reinforcing one or more materials to the matrix. The properties of a composite mainly depend on the factors like reinforcement material and processing method. The main objectives of the present work were to investigate the effect on properties such as density, surface roughness, microhardness, fracture toughness and microstructure varying with reinforcement of MgO, MWCNTs and ZrO2 in the alumina matrix were conducted using microwave and spark plasma sintering through powder metallurgy route. Investigations with reinforcement of MgO and ZrO2 in the alumina matrix were conducted using microwave sintering process in which the powders were compacted at a pressure 100 MPa and sintered at 1300°C, 1450°C, 1500°C, and 1550°C and held for 20 minutes under pressure-less condition. Similarly, the reinforcement of MgO and ZrO2 in the alumina matrix was investigated using spark plasma sintering process in which heat and pressure were applied simultaneously at a pressure 60 MPa and sintered at 1250°C, 1300°C, and 1350°C, and held for 5 minutes. In the MW and SPS sintering process, the composition varying with reinforcement of MgO (0.5 vol. %, 1 vol. % and 2 vol. %) and 3 mol % yttria stabilized zirconia (5 vol. %, 10 vol. % and 15 vol. %) in the alumina matrix and developed of MgO-ZTA ceramic composites. The optimum properties were found with reinforcement of 1 vol. % of MgO and 10 vol. % of ZrO2 in the alumina matrix using microwave sintering. The highest density (97.79 %), minimum surface roughness (1.511 μm), highest micro-hardness (18.09 GPa), and minimum average grain size (0.466 μm) were obtained. The highest fracture toughness (6.6 MPa.m1/2) was found with reinforcement of 1 vol. % of MgO and 15 vol. % of ZrO2 in the alumina matrix, at a sintering temperature of 1500°C for holding time 20 minutes. Similarly, the optimum properties were found with reinforcement of 1 vol. % of MgO and 10 vol. % of ZrO2 in the Al2O3 matrix were conducted using spark plasma sintering process. The highest relative density (99.68 %), minimum surface roughness (1.123 μm), highest microhardness (19.46 GPa) and minimum average grain size (0.595 μm). The highest fracture toughness (6.7 MPa.m1/2) was found with reinforcement of 1 vol. % of MgO and 15 vol. % of ZrO2 in the alumina matrix, at a sintering temperature of 1300°C and holding time 5 minutes. Investigations with reinforcement of functionalized MWCNTs and ZrO2 in the alumina matrix were conducted using microwave sintering process in which the powders were compacted at a pressure 100 MPa and sintered at 1450°C, 1500°C, and 1550°C and held for 20 minutes under pressure-less condition. Similarly, the reinforcement of MWCNTs and ZrO2 in the alumina matrix was investigated were conducted using spark plasma sintering process in which heat and pressure were applied simultaneously at a pressure 60 MPa and sintered at 1250°C, 1300°C, and 1350°C, and held for 5 minutes. In the MW and SPS sintering process, the varying with reinforcement of functionalized MWCNTs (0.5 vol. %, 1 vol. % and 2 vol. %) and 3 mol % yttria stabilized zirconia (5 vol. %, 10 vol. % and 15 vol. %) in the alumina matrix and developed of MWCNTs-ZTA ceramic composites. The optimum properties were found with the reinforcement of 1 vol. % of functionalized MWCNTs and 10 vol. % of ZrO2 in the alumina matrix were conducted using microwave sintering. The highest density (97.35 %), minimum surface roughness (1.134 μm), highest microhardness (16.31 GPa), and minimum average grain size (0.461 μm) were obtained. The highest fracture toughness (8.11 MPa.m1/2) was found with reinforcement of 1 vol. % of MWCNTs and 15 vol. % of ZrO2 in the alumina matrix, at a sintering temperature of 1500°C for holding time 20 minutes. Similarly, the optimum properties were found with reinforcement of 1 vol. % of functionalized MWCNTs and 10 vol. % of ZrO2 in the Al2O3 matrix were conducted using spark plasma sintering process. The highest relative density (97.80 %), minimum surface roughness (1.125 μm), highest microhardness (17.65 GPa) and minimum average grain size (0.3947 μm). The highest fracture toughness (8.5 MPa.m1/2) was found with reinforcement of 1 vol. % of MWCNTs and 15 vol. % of ZrO2 in the alumina matrix, at a sintering temperature of 1300°C for holding time 5 minutes. The mechanical properties and uniform disperse microstructure of SPS sintered samples were observed to be superior compared to the MW sintered samples. Among all the samples, highest density, minimum surface roughness, highest microhardness, and minimum average grain size were observed with the MgO-ZTA composite processed through SPS while highest fracture toughness was observed with the MWCNTs-ZTA composite processed through SPS. The minimum value of COF and wear rate was observed with the developed MgO-ZTA composite processed through SPS.