Thermal stability of alumina thin films containing γ-Al2O3 phase prepared by reactive magnetron sputtering

The present work investigates the microstructure and chemical composition of macroparticles incorporated in arc evaporated (Al,Cr)2O3 coatings. According to scanning and transmission electron microscopy analysis, two different types of macroparticles with a distinct difference in their shape and a noticeable variation in their chemical composition, i.e. the Al/Cr ratio, can be distinguished. In addition, the transformations on the surface of the corresponding Al–Cr compound cathodes during the evaporation process in O2 atmosphere are studied by scanning electron microscopy and X-ray diffraction. Beside the virgin cathode material, a reaction layer consisting of various intermetallic AlxCry phases with a fine-grained morphology and pillar-shaped Al2O3 islands was found. Correlations between the origin of the macroparticles and the observed modifications at the surface of the Al–Cr cathode are discussed.

Cathodic arc deposition of (Al,Cr)2O3: Macroparticles and cathode surface modifications

Structural and mechanical properties of Cr–Al–O–N thin films grown by cathodic arc deposition

http://liu.diva-portal.org/smash/get/diva2:398416/FULLTEXT02.pdf

Face-centered cubic (Al1 − xCrx)2O3

Cr(2)AlC coating was deposited at 370 and 500 degrees C by D.C. magnetron sputtering from an as-synthesized bulk Cr(2)AlC target. The phase composition and preferential orientation of the coating were investigated using XRD, and the microstructure of the coating was characterized by TEM. Results indicated that Cr(2)AlC coating with a strong (110) preferential orientation could be obtained. The coating microstructure was clearly affected by the deposition temperature. At 370 degrees C, the deposited coating possessed a triple-layered structure with an alpha-(Cr, Al)(2)O(3) inner layer, an amorphous intermediate layer and a crystalline Cr(2)AlC outer layer. However, the coating deposited at 500 degrees C had a single-layered structure consisting of crystalline Cr(2)AlC layer. The growth mechanism of the Cr(2)AlC coating at different deposition temperatures is discussed. (C) 2010 Elsevier B.V. All rights reserved.

Variation of microstructure and composition of the Cr2AlC coating prepared by sputtering at 370 and 500 °C

The development of new coatings with superior functionalities for high performance cutting tools is a key challenge in manufacturing. In this context, the synthesis of aluminium oxide and derivative oxide thin films is attracting large scientific and technical interests. The present paper addresses fundamental materials science-based aspects of the physical vapour deposition (PVD) growth of Al–Cr–O thin films at a substrate temperature of 500 °C. A combinatorial experimental approach was chosen to describe the growth and microstructure evolution of Al–Cr–O thin films by means of reactive r.f. magnetron sputtering. A segmented target consisting of two half plates of Al and Cr was used for the deposition carried out under stationary conditions in a laboratory-scale PVD coater. Opposite to the cathode five substrate samples were placed in a line. The r.f. cathode power was set to 500 W and the r.f. substrate bias was set to − 100 V. The total gas pressure was kept constant at 0.4 Pa for all experiments with a fixed ratio of oxygen to argon gas flow. Detailed results on the coatings composition, constitution, microstructure and properties as a function of the elemental composition are presented. X-Ray Diffraction (XRD), X-Ray Reflection (XRR), Transmission Electron Microscopy (TEM) and Electron Probe Microanalysis (EPMA) studies prove the growth of nanocrystalline, stoichiometric, metastable corundum-like solid solution strengthened α-(Al 1 −  x ,Cr x ) 2 O 3 thin films with a high degree of crystallinity, grain sizes between 27 ± 6 nm (in the case of Al-rich coatings) and 44 ± 17 nm (in the case of Cr-rich coatings), Vickers micro hardness values up to 2620 ± 80 HV0.05 and thin film densities between 4.00 g/cm³ (in the case of Al-rich coatings) and 4.86 g/cm³ (in the case of Cr-rich coatings).

V. Schier

Papers

Combinatorial approach to the growth of α-(Al1 − x,Crx)2O3 solid solution strengthened thin films by reactive r.f. magnetron sputtering