Phase transformation in kappa- and gamma-Al2O3 coatings on cutting tool inserts
2009 (English)In: Surface & Coatings Technology, ISSN 0257-8972, Vol. 203, no 12, 1682-1688 p.Article in journal (Refereed) Published
The phase transformation in as-deposited, metastable kappa- and gamma-alumina coatings on cutting inserts has been studied by a combination of X-ray diffraction, scanning electron microscopy and cathodoluminescence. In the case of kappa-alumina, mechanical forces during metal cutting lower the transformation temperature of the metastable phases to the thermodynamically stable alpha-alumina phase from 1050 degrees C to 930 degrees C. This is the reason why that coating has a similar performance during metal cutting when compared to the stable ce-alumina phase. The transformation temperature in gamma-alumina coated cutting tools is found to be as low as 950-975 degrees C. Cathodoluminescence (CL) has been demonstrated as a possible method for differentiation between the various alumina phases. Specifically, both kappa- and gamma-alumina films have revealed a strong room temperature CL with different peak energies depending on the phase. CL of the metastable alumina coatings annealed at the transformation temperatures corresponds to the stable alpha-alumina phase.
Place, publisher, year, edition, pages
2009. Vol. 203, no 12, 1682-1688 p.
Alumina, Phase transformation, Coatings, X-ray diffraction, Cathodoluminescence
IdentifiersURN: urn:nbn:se:liu:diva-17601DOI: 10.1016/j.surfcoat.2008.12.028OAI: oai:DiVA.org:liu-17601DiVA: diva2:210778