Influência da nióbia no óxido de alumínio eletrofundido para aplicações abrasivas
Resumen
Abrasives are materials that have as main characteristics their cutting and
grinding power. In its most common crystalline form, aluminum oxide, due to its
high melting point, high hardness and mechanical resistance, is suitable for
refractory and abrasive applications. With the increase in the consumption of
abrasives and the market's need for more efficient grinding, polishing and cutting
tools, this work aimed to verify the influence of niobium oxide on the physical chemical properties of electrofused aluminum oxide. Thus, the work addresses
the electrofusion of calcined alumina with the addition of niobia, as well as a
comparison of the mechanical properties of this material with emphasis on the
abrasive characteristic, comparison with white fused aluminum oxide and brown
fused aluminum oxide conventionally found in this market. The samples of the
materials obtained were analyzed by X-Ray Diffraction and Fluorescence (DRX
and FRX), wear test, instrumented nanohardness, real and bulk density, linear
thermal expansion, refractoriness and microstructural characterization by Scan
Electron Microscopy coupled to EDS. The results showed that the addition of
niobia significantly influenced the increase in the abrasiveness of aluminum
oxide, the wear test showed a removal of metallic material 6.6% higher than white
fused aluminum oxide and 13.4% higher than brown fused aluminum oxide.
Another important influence of the addition of Niobia in aluminum fused oxide was
the increase in the thermal expansion coefficient and the reduction in
refractoriness. While the white and brown aluminum oxides varied less than 1%
of the initial length (at a temperature of 1250°C), the oxide with the addition of
niobia presented a variation of 2.78% (at a temperature of 1174.8°C). Thus, it is
proven in this work that niobia exerts a great influence on the physicochemical
properties of fused aluminum oxides.
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