Multi layer alumina coatings consisting of layers of either pure α-A12 O3 or κ-Al2O3, were deposited in a hot wall CVD reactor. In order to nucleate and grow a desired alumina polymorph (α/κ) in each layer, thin α- and κ-modification layers were deposited between the alumina layers. This investigation examines the interfacial structure of the κ-modification and the alumina layers. The materials were examined using a combination of XRD, SEM, TEM and EDX.
The κ-modification layers exhibited an FCC structure and were composed of (Ti,AI)(C,O). Orientation relationships were frequently found at the (i) α-A12O3/κ-modification/κ-A12O3 layer interfaces and (ii) κ- A12O3/κ-modification/κ- A12O3 layer interfaces: ![](//static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20190527050136232-0141:S1946427400309356:S1946427400309356_inline1.gif?pub-status=live)