Microstructure and Properties of Mixed α’+β’-Sialons
The microstructure and mechanical properties of fully dense yttrium-containing α’ + β’-sialon ceramics prepared by gas pressure sintering were studied. The typical microstructure of mixed α’+β’-sialon ceramics consists of needle-like grains of the β’-phase (the ratio of length to width is about 7) dispersed in a matrix of equi-axed α’-sialon grains (mean grain size is about 3 µm) with a small fraction of an yttrium-rich amorphous phase (atom ratio Y:Si:Al = 0.8: 1.0:0.5) at grain boundaries. Vickers hardness (HvO.5) and fracture toughness (KIC) were measured by using the indentation technique and the biaxial bending strength (σbi) was determined with the “ball-on-ring” test. The relationships between the composition, microstructure and mechanical properties are discussed.
Unable to display preview. Download preview PDF.
- 3.Thompson, D.P., Sun, W.Y. and Walls, P.A., α’ — β’ and O’-β’-Sialon Ceramics, Ceramic Materials and Components for Engines, Eds. Bunk, W. and Hausner, H., DKG, Berlin, 1986, p643.Google Scholar
- 4.Cao, G.Z., Metselaar, R. and Ziegler, G., Gas Pressure Sintering of α’-Sialon Ceramics, Euro-Ceramics. I, eds. de With, G., Terpstra, R.A. and Metselaar, R., Elsevier Science Publ., London, 1989, p346.Google Scholar
- 6.Ekström, T., Fabrication and Properties of Yttrium Sialon Ceramics, Mater. Sci. Forum, 34/36(1988)605.Google Scholar
- 7.Cao, G.Z., Preparation and Characterization of α’-Sialon Ceramics, Ph.D Thesis, Eindhoven University of Technology, April, 1991.Google Scholar
- 9.Dortmans, L.J.M.G. and de With, G., Weakest-link Failure Predictions for Ceramics Using Finite Element Post-processing, to be published in J. Euro-Ceram. Soc..Google Scholar
- 10.Kokmeijer, E., Sintenng Behaviour and Properties of β’-Si3Al3O3N5 Ceramics, Ph.D Thesis, Eindhoven University of Technology, Oct., 1990.Google Scholar