Influence of the nucleation surface on the growth of epitaxial Al2O3 thermal CVD films deposited on cemented carbides

• Published in: Materials & Design Vol. 216; p. 110601
• Main Authors: Zhu, Maoxiang, Achache, Sofiane, Emo, Mélanie, Borroto Ramírez, Alejandro, Pierson, Jean-François, Sanchette, Frédéric
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2022; Elsevier
• Subjects: Alumina; Bonding layer; Chemical Sciences; Epitaxial growth; Physics; Thermal chemical vapor deposition (CVD); Thermal chemical vapor deposition (CVD); Bonding layer; Epitaxial growth; Alumina; Thermal chemical vapor deposition (CVD) Alumina Epitaxial growth Bonding layer
• ISSN: 0264-1275; 0261-3069; 1873-4197; 0264-1275
• DOI: 10.1016/j.matdes.2022.110601

[Display omitted] •The nucleation of α- and κ-Al2O3 can be controlled with specific nucleation treatments.•α-Al2O3 is the preferred alumina phase to be deposited without any nucleation treatment.•α-Al2O3 is grown epitaxially on rutile (TiO2), with (1¯20)α-Al2O3//(101¯)rutile, (003)α-Al2O3//(010)rutile and [210]α-Al2O3//[101]rutile.•κ-Al2O3 is grown epitaxially on Ti(C,N), with (100)κ-Al2O3//(1¯1¯1)Ti(C,N),(01¯3)κ-Al2O3//(2¯20)Ti(C,N) and [031]κ-Al2O3//[112]Ti(C,N). This work aims at understanding the nucleation and growth of alumina films grown on Ti(C,N)-based layers using an industrial-scale CVD system. Firstly, Al2O3 layer was deposited on Ti(C,N)-based layers without any nucleation treatment, pure α-Al2O3 is obtained, whereas no orientation relationship at the Ti(C,N)/α-Al2O3 layers interface can be observed. Secondly, Al2O3 layer was deposited on the bonding layer consisting of rutile TiO2, which is obtained by oxidizing the uppermost part of Ti(C,N)-based layers. Herein, α-Al2O3 single-phased layer is obtained, and the epitaxial growth of α-Al2O3 on rutile is observed. The orientation relationships can be found as:(1¯20)α-Al2O3//(101¯)rutile, (003)α-Al2O3//(010)rutile and [210]α-Al2O3//[101]rutile. Finally, Al2O3 layer was deposited on the bonding layer, produced from a TiCl4-H2-N2-CH4-CO-AlCl3 gas mixture. Regarding this intermediate layer, despite additions of CO and AlCl3, no evidence for oxide phases, e.g. TiO2 and Al2O3 can be found, while Ti(C,N) needle-shaped grains develop. In this case, κ-Al2O3 is epitaxially grown on Ti(C,N), with the orientation relationships found as:.(01¯3)κ-Al2O3//(2¯20)Ti(C,N), (100)κ-Al2O3//(1¯1¯1)Ti(C,N) and [031]κ-Al2O3//[112]Ti(C,N). Since processing parameters for the alumina depositions were always the same, it is revealed that the nucleation of α-Al2O3 and κ-Al2O3 can be accurately controlled with deposition of specific bonding layers.