Thermal stability of doped CVD κ-Al2O3 coatings

Characterization of the Near-Eutectic Al2O3–40 wt% ZrO2Composite Coating Fabricated by Atmospheric Plasma Spray. Part I: Preparation and Characterization of Nano Al2O3–ZrO2Powder Using Sol–Gel Method

“…It was found that the xerogel was mainly consisted of AlOOH. Diffraction peaks of Al(OH) 3 and ZrO OH 2 were not found in xerogel, which indicated that the two compounds were amorphous.…”

“…The vibrations appearing in the range 2085 cm −1 could be assigned to the coupling effect of stretching and bending vibrations of -OH groups. The peaks at 1384 cm −1 and 1643 cm −1 were due to the stretching vibration of NH 3 When NH 4 OH solution was added to mixed aqueous solution of Al NO 3 3 · 9H 2 O and ZrOCl 2 · 8H 2 O, and hydrolysis and condensation reaction were accelerated. The detailed process can be explained as follows: A part of Al OH 3 transformed to AlOOH at the presence of OH − in the sol-gel system:…”

“…Coatings based on alumina (Al 2 O 3 ) have many advantages, such as high hardness and strength, which has been studied for a number of applications [1][2][3]. However, the brittleness still hampers coating wide potential application.…”

PVD and CVD Hard Coatings

“…In CVD, AlCl 3 and CO 2 are used as precursors (Tingey, 1966). Transformation of k-Al 2 O 3 into the stable a-Al 2 O 3 modification occurs at a temperature of approximately 1000 C (Hochauer et al, 2010), and results in coating cracking and delamination due to the associated volume change. Furthermore, the deposition conditions during Al 2 O 3 nucleation (Ruppi, 2005) and surface treatment procedures of the substrate (Danzinger, Haubner, & Lux, 1991) are crucial for the phase formation.…”

Coating Applications for Cutting Tools

“…The modification of the Al 2 O 3 phase due to additional elements was extensively investigated. In case of k-Al 2 O 3 coatings, stabilization of the thermal transformation was one goal besides the improvement of mechanical properties (Hochauer et al, 2010;Kathrein, 2001;Kathrein, Schintlmeister, Wallgram, & Schleinkofer, 2003;Okude, Tomita, Nakamura, & Osada, 2011). The doping of a-Al 2 O 3 was investigated to enhance the tribological properties as well as the cutting performance (Hochauer et al, 2008;Kathrein, 2001).…”