Smart materials in the SiAlON-SiC-Al2O3 system

International Conference and Expo on Ceramics

August 17-18, 2015 Chicago, USA

Z Kovziridze, N Nijaradze, G Tabatadze, N Darakhvelidze and Z Mestvirishvili

Posters-Accepted Abstracts: J Material Sci Eng

Abstract :

Purpose: In the present paper SiAlON-containing nano-composite was obtained through alum-thermal and nitrogen process
on the base of geopolymer (Ukraine), aluminum nano-powder, silicium, aluminum oxide, silicon carbide with little admixes
of yttrium oxide, magnesium oxide and glass perlite (Aragac, Armenia).
Methods: Composite was obtained in the nitrogen medium, by the reactive baking method at 1450°C. The advantage of this
method is that compounds, which are newly formed thanks to interaction going on at thermal treatment: Si3N4, Si and AlN
reactive which contributes to SiAlON formation at relatively low temperature, at 1300-1350°C. It is evident that inculcation of
α - Al2O3 and ALN in crystal skeleton of ß-Si3N4 is easier since at this temperature interval crystal skeleton of Si3N4 is still in the
process of formation. It should also be stated that strength and wear resistance of SiAlONs increase in their presence in silicium
carbamide- and corundum -containing composites. The paper offers processes of formation of SiC-SiAlON and Al2O3-SiAlON
and ß-SiAlON composites and describes their physical and technical properties.
Results: Open porosity of the obtained materials equaled to 15-16 %. Materials consisted of only SiAlONs. To receive compact
materials the composites were grinded in planetary mill for eight hours, then they was cleaned from admixtures and the
obtained powder was hotly pressed at 17500C under 25 MPa. Standing time at final temperature equaled to seven min. The
results of samples testing: Density, g/cm3=3.24; Thermal expansion coefficient, 1/grad 10-6(800)=2.7-3.0; Hardness, HRA=94,
HV=18 GPa; Flexural Strength, 500-550 MPa. Phase composition of the composites was studied by X-ray diffraction method,
while the structure was studied by the use of optic and electron microscope.
Conclusion: Obtained materials are used in protecting jackets of thermo couples used for melted metal temperature measuring
(18-20 measuring) and for constructions used for placing objects in factory furnaces, and for cutting ceramics.

Biography :

Zviad Kovziridze is the Head of the Department of the technology of composite materials and articles of Georgian Technical University; Scientific supervisor of the center
of bio-nanoceramics and nanocomposites material science of GTU. He is the Member of the Council of International Ceramists Federation (ICF); Member of the Council
of European ceramists’ Association (ECERS). He is also President of Georgian Ceramic Association and Editor-in-chief of journal “Ceramic” of the Georgian Ceramists
Association, “Journal of Ceramic Science and Technology”. He has 168 publications in repute journals, among them 4 textbook, 7 monograph and 13 author’s certificates.