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Acoustic Emission During Firing of the Illite-Based Ceramics with Fly Ash Addition

100%

Knapek M., Húlan T., Dobroň P., Chmelík F., Trník A., Štubňa I.

Acta Physica Polonica A

2015

vol. 128

issue 4

783-786

In this work, illite-based ceramic body with power plant fly ash addition (60 wt.% of illite, 30 wt.% of fly ash and 10 wt.% of illite fired at 1100°C) was investigated by the thermal analysis techniques (differential thermal analysis, thermodilatometry and thermogravimetry) and the acoustic emission technique. The green body was heated up to 1100°C at three different rates 2.5, 5, 10 K/min. The most intense acoustic emission was recorded at the highest rate 10 K/min. Mutual correlations between thermal analyses and acoustic emission data were also examined. The first acoustic emission response appears at 430°C, corresponding to a small endotherm on the DTA curve, where the thermal decomposition of mineral portlandite takes place. In the temperature range from 600 to 900°C, high acoustic emission activity correlates with dehydroxylation and expansion of the sample. At temperatures higher than 800°C, the source of acoustic emission signals is the thermal decomposition of calcite. The amorphous phase created from illite at 920°C becomes pyroplastic, therefore it is not documented by the acoustic emission technique.

The Study of the Behavior of Constrained Groove Pressed Magnesium Alloy after Heat Treatment

84%

Zimina M., Bohlen J., Letzig D., Kurz G., Poková M., Knapek M., Zrník J., Cieslar M.

Acta Physica Polonica A

2015

vol. 128

issue 4

775-778

In this work twin-roll cast AZ31 magnesium strip of thickness 5.6 mm was subjected to the heat treatment and further constrained groove pressing. A comparison of the microstructure and microhardness of as-cast, constrained groove pressed and annealed material was carried out. The twin-roll cast strip exhibits an inhomogeneous structure which is replaced by a finer and uniform recrystallized one after aging at 450°C for 10 h. A significant increase of the microhardness was observed accompanied by a pronounce grain refinement. Nevertheless, the distribution of the grain size is unequal along the specimen width. Thermal stability of the deformed structure during subsequent annealing was investigated. It was shown that higher annealing temperatures result in a formation of a more uniform recrystallized structure and in a significant drop of microhardness down to the values obtained for as-cast alloy.

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2 Acta Physica Polonica A

2 2015

2 Knapek M.

1 Bohlen J.

1 Chmelík F.

1 Cieslar M.

1 Dobroň P.

1 Húlan T.

1 Kurz G.

1 Letzig D.

1 Poková M.

1 Trník A.

1 Zimina M.

1 Zrník J.

1 Štubňa I.

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Acoustic Emission During Firing of the Illite-Based Ceramics with Fly Ash Addition

The Study of the Behavior of Constrained Groove Pressed Magnesium Alloy after Heat Treatment