Composites Al2O3-SiCw
Agnieszka Krawczyńska, Krzysztof Biesiada, Andrzej Olszyna Politechnika Warszawska, Wydział Inżynierii Materiałowej, ul. Wołoska 141, 02-507 Warszawa
Quarterly No. 2, 2006 pages 38-43
DOI:
keywords: ceramic materials, ceramic composites, fracture toughness
abstract The study is concerned with the modification of the properties of Al2O3, in particular aimed at improving the fracture toughness of this material, by introducing ceramic whiskers of the silicon carbide (β-SiC) into its matrix. The technological operations involved in the production of the Al2O3+x%wt.SiCw (x = 0, 5, 10, 15, 20) composite are: mixing the starting powders, drying the mixture, granulating, uniaxial pressing at p = 20 MPa, isostatic compacting at p = 120 MPa, and hot pressing sintering in T = 1650°C, p = 35 MPa for 1 h in argon (Fig. 3). The physical properties of the Al2O3+x%SiCw composites thus produced, such as the density, porosity and absorptivity were determined using the hydrostatic method (Fig. 4). The phases identified in the Al2O3+15%SiCw composite by a qualitative phase analysis were Al2O3 and two variations of β-SiC (Fig. 5). Investigation the strength properties of the composite, such as the hardness (HV) and fracture toughness (Vickers method) (Fig. 7). The Al2O3+x%wt.SiCw (x = 0, 5, 10, 15, 20) composites hot-pressed under a pressure of 35 MPa show a high hardness of 18 GPa (for Al2O3+20%wt.SiCw) and stress intensity factor KIC of 6 MPa ⋅ m1/2 (for Al2O3+20%wt.SiCw). The value of the stress intensity factor measured in the Al2O3+x%wt.SiCw (x = 0, 5, 10, 15, 20) composites can be attributed to the presence of the whiskers SiC (crack deviation and bridging).