Vickers hardness and fracture toughness of selected ceramic composites
Zbigniew Pędzich*, Jan Piekarczyk*, Ludosław Stobierski*, Magdalena Szutkowska**, Elżbieta Walat** *Akademia Górniczo-Hutnicza, Wydział Inżynierii Materiałowej i Ceramiki, al. Mickiewicza 30, 30-059 Kraków **Instytut Obróbki Skrawaniem, ul. Wrocławska 37a, 30-011 Kraków
Annals 3 No. 7, 2003 pages 296-300
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abstract The paper presents results of the Vickers hardness and the fracture toughness investigations of several materials: α-alumina (α-Al2O3), yttria-stabilized tetragonal zirconia polycrystals (TZP), silicon carbide (SiC), titanium-silicon carbide (Ti3SiC2) and composites on their matrix. It was established that values of Vickers hardness measured under the lowest loads are significantly lower that values achieved under higher loads (see Fig. 3). They also show big values of standard deviation. The results of KIc investigations (see Fig. 4 and Table 1) show that one mustn’t to apply indentation method uncritically. Measured KIc values strongly depend on used loads, especially under loads when cracks started to appear. At this range measured KIc values reach extremely high level. They decrease with load increase. It is obvious that it is necessary to select the proper load for each material. The conformity between two methods of KIc measurements (indentation and SENB) is different for investigated materials. Relatively the best conformity is achieved for oxide materials and composites on their matrixes (especially for zirconia). Application of the indentation method for Ti3SiC2-based materials gave the worst conformity of results with these achieved by SENB method. It is probably due to very complicated way of cracking in these materials. Key words: structural ceramics, ceramic composites, Vickerss hardness, fracture toughness