Fracture Properties of α– and ĸ–Al2O3 Hard Coatings Deposited by Chemical Vapor Deposition

Abstract

Although α– and κ–Al2O3 hard coatings deposited by chemical vapor deposition are well established in the metal-cutting industry for their ability to increase the performance and lifetime of cutting tools, the literature on their fracture properties is scarce. Thus, within this study, the microstructure and mechanical properties of α– and κ–Al2O3 coatings were investigated and compared to each other. X-ray diffraction and scanning electron microscopy combined with electron backscatter diffraction showed that both coatings exhibited a fiber texture, where the α-Al2O3 coating displayed a (0001) texture and the κ–Al2O3 coating a (001) texture with a certain (013) contribution. Higher hardness and Young’s modulus values of 31.0 ± 0.9 GPa and 474.6 ± 12.5 GPa, respectively, were obtained for the α–Al2O3 coating, compared to 24.2 ± 0.8 GPa and 356.8 ± 7.9 GPa for κ–Al2O3. While the α–Al2O3 coating exhibited a higher fracture stress of 8.1 ± 0.3 GPa (compared to 6.4 ± 0.6 GPa for κ–Al2O3), the κ–Al2O3 coating showed a higher fracture toughness of 4.4 ± 0.3 MPa*m1/2 (compared to 3.2 ± 0.3 MPa*m1/2 for alpha).

Characteristics and Cutting Performance of CVD Al2O3 Multilayer Coatings Deposited on Tungsten Carbide Cutting Inserts in Turning of 24CrMoV5-1 Steel

“…Twenty-five indentations were performed for each sample and an average value was considered. The Oliver and Pharr method and the Poisson's ratio of 0.24 for both αand κ-Al 2 O 3 were used for calculations [16,17]. Vickers hardness HV 0.05 values were measured using a Wilson ® TUKONTM 1202 (Buehler, Leinfelden-Echtergingen, Germany): ten indentations were performed for each sample, and an average value was considered [18].…”

Effect of Al2O3 on Microstructure and Corrosion Characteristics of Al/Al2O3 Composite Coatings Prepared by Cold Spraying

“…Cold spraying technology is a surface coating technology developed based on the principles of gas dynamics and high-speed collision dynamics [12][13][14]. Cold spraying technology has the characteristics of high spraying rate, the high strength of the sprayed bonding layer, dense coating, and low temperature compared to preparation methods such as thermal spraying [15], electroplating [16], laser cladding [17], and chemical vapor deposition (CVD) [18]. In recent years, scholars have investigated the properties of cold-sprayed Al-MMC coatings.…”