Al 2 O 3-YAG composite was obtained by sintering of porous Al 2 O 3 preforms infiltrated with water solution of aluminium nitrate nonahydrate, Al(NO 3) 3 •9H 2 O and yttrium nitrate hexahydrate, Y(NO 3) 3 •6H 2 O. Al 2 O 3 preforms with porosity varying from 26 to 50% were obtained after sintering at temperature ranging from 1100 to 1500 °C. Sintering of the infiltrated Al 2 O 3 preforms led to formation of YAG particles due to reaction between Y 2 O 3 and Al 2 O 3 at high temperature. It was found that variation of porosity of alumina preforms and sintering temperature is an effective way to fabricate Al 2 O 3-YAG composite with an unusual combination of properties. Open porosity was in the range 15-35%, specific surface was 0.6-6.1 m 2 /g, pore size was 150-900 nm whereas compressive strength was from 50 to 250 MPa. The effect of sintering temperature on YAG formation and phase composition were investigated using X-ray diffractometry whereas microstructure of the composite was analysed by scanning electron microscopy.
The objective of this manuscript was to investigate the synthesis of SiC by carbothermal– reduction reactions of sepiolite. Sepiolite of Serbian origin and carbon (from various precursors) as a reducing agent were used. The green bodies with various C/SiO2 ratios were carbonized at 1073 K and heattreated at 1673 K in a controlled Ar flow atmosphere. Phase evolution and phase content were followed as a function of C/SiO2 ratio and carbon origin. The starting materials and products were characterized by means of XRD and SEM. The results show that sepiolite can be very effective source for obtaining silicon carbide powders.
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