subsequent grain growth during sintering resulted in highly anisotropic microstructure of individual Microsco 
layer, which is shown in Fig. 5. The bimodal microstructure consisting of fine-grained matrix and Current: 
large elongated grains highlights the influence of seed particles on the final microstructure. The 
large, rod-like grains, which were developed from the seed particles, exhibit a typical core/rim SH 
structure. 0. 3p" 
Institule 0 
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Physics In 
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Fig. 4: Layered silicon nitride based composite. Fig. 5: Aligned Si3N4 grains in layered —— 
composite. artes 
In sake of excellent mechanical properties of layered composites the major disadvantage of layered oma 
material design is the strong properties anisotropy. However, there exist many applications for this 
kind of materials. Experimes 
Conclusions i 
This brief review showed how powerful tool is the microstructural design with respect to the AL 
properties of polycrystalline ceramic materials. The small change in the sintering additive sen 
chemistry, heating regime, seeding, layer sequencing, etc. have an enormous effect on the N br 
mechanical properties. The field of microstructure analysis with respect to the properties of ceramic a ' 
body is still opened for the further scientific investigation. WO 
References fh tag: 
(1) D. Galusek, P.C. Twigg., F.L. Riley, Wear, 233-35 (1999) 588. Of vans 
(2) P. Sajgalik, M.J. Hoffmann, “Engineering Ceramics ‘92”, Reproprint (1993) 89. 0 eo 
(3) P. Sajgalik, M.J. Hoffmann, J. Am. Ceram. Soc., 78 (1995) 2619. Poss, 
(4) Z. Lencés, P. Sajgalik, M. Toriyama, MLE. Brito, S. Kanzaki, J. Eur. Ceram. Soc., 20 (2000) Al 
2347 All samp 
metallogr, 
Solutions 
Were app 
Phase con 
Optical me 
HG. 
208