ALİ ÇELİK

Oxidation Behavior of Y2O3 and Er2O3-doped-α/β-SiAlON Ceramics

SiAlON ceramics are successfully utilized in applications such as refractories used for metal melting and cutting tools for high speed machining of metals in which high temperature properties are important. As being one of the main indication of high temperature resistance for such applications, oxidation resistance of this materials are affected by microstructural features, type and amount of the rare-earth (RE) elements in α-SiAlON and grain boundary phase (GBP). In this study, oxidation behavior of α/β-SiAlON ceramics prepared by Er2O3 as well as Y2O3, which is one of the most widely used RE-oxide in commercial SiAlON compositions, was investigated comparatively. A slight difference was observed in oxidation resistance of Er2O3 and Y2O3 containing SiAlON ceramics due to their slightly different crystallinity of GBPs.

Y2O3 ve Er2O3-katkılı α/β/-SiAlON Seramiklerinin Oksidasyon Davranışları

SiAlON seramikleri metal ergitme işleminde kullanılan refrakterler ve metallerin yüksek kesme hızlarında talaşlı imalatında kullanılan kesici takımlar gibi yüksek sıcaklık özelliklerinin ön planda olduğu uygulamalarda başarıyla kullanılan malzemelerdir. Bu malzemelerin oksidasyon ve korozyon direnci gibi yüksek sıcaklık özellikleri ise mikroyapısal özellikleri, faz özellikleri ve kullanılan nadir toprak (RE) elementleri ile belirlenmektedir. Bu çalışmada ve sağladığı yüksek oksidasyon direnci ile SiAlON seramiklerinin üretiminde en yaygın kullanılan nadir toprak elementi oksitlerinden bir tanesi olan Y2O3 ile birlikte önemli bir potansiyele sahip olan Er2O3 ilaveleri kullanılarak hazırlanan α/β-SiAlON seramiklerinin kıyaslamalı oksidasyon davranışları incelenmiştir. Oksidasyon direnci açısından her iki ilavenin benzer özelliklere sahip olduğu, farklılığın ise tane sınırı fazlarının kristalizasyon derecelerinden kaynaklandığı bulunmuştur.

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