engleski

A comparative study of the influence of milling media on the structural and microstructural changes in monoclinic ZrO2

Structural and microstructural developments of m-ZrO2 during the ball-milling process strongly depend on the type of milling assembly used. Ball-milling with corundum milling assembly cause almost complete amorphization of the starting m-ZrO2, while ball-milling with agate or stainless steel assembly cause a decrease of the volume-averaged domain size up to similar to 9 nm or similar to 13 nm, respectively. Regardless of the type of milling assembly, a small amount of t-ZrO2 appeared in the milled products. The onset of m-ZrO2 -> t-ZrO2 transition occurred only in products ball-milled with stainless steel assembly and resulted in a complete transition after 20 h and probable further transition into c-ZrO2 after prolonged milling. The stabilization of t- and c-ZrO2 in this products resulted from the incorporation of aliovalent cations due to the wear and oxidation of the milling media. The small fraction of t-ZrO2 in the product milled with corundum or agate milling assembly could not be clearly connected with the effect of crystallite size decrease. (c) 2006 Elsevier Ltd. All rights reserved.

milling; electron microscopy; X-ray methods; ZrO2; Rietveld

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