Effects of reference materials on texture coefficients determined for a CVD α-Al2O3 coating

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).

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“…surface of the coating [24]. Additionally, reflections stemming from the TiCN base lay and the WC substrate are evident.…”

Section: Microstructurementioning

confidence: 92%

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

Konstantiniuk

Tkadletz

Czettl³

et al. 2021

Coatings

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“…Introduction of the texture-control on an industrial scale [23,24], facilitating the commercial production of (0001) textured α-Al 2 O 3 coatings on medium temperature MTCVD Ti(C,N) intermediate layers has thus been one of the most important recent advances in CVD tool coatings. These α-Al 2 O 3 coatings have been considered state-of-the-art for more than ten years [25].…”

Section: Introductionmentioning

confidence: 99%

Influence of Process Conditions on the Growth and Texture of CVD Alpha-Alumina

Ruppi¹

2020

Coatings

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In the present study, the influence of experimental variables on the growth characteristics and texture development in chemically vapour deposited α-Al2O3 coatings was investigated. The emphasis was on the effects of H2S. The α-Al2O3 layers were deposited from the AlCl3-H2-CO2-HCl-H2S precursor system onto intermediate Ti(C,N) layers. The substrate was cemented carbide. The coatings were characterized with respect to microstructure and texture using X-ray diffraction, scanning electron microscopy and electron back-scattering diffraction. The observations were unpredictable, suggesting that in addition to the growth rate, H2S strongly affected the texture of the α-Al2O3 coatings. The uncatalyzed α-Al2O3 coatings (H2S = 0) developed (11 2 ¯ 0) texture. With the increment of H2S concentration the texture changed from (11 2 ¯ 0) texture through (10 1 ¯ 0), (10 1 ¯ 2) and (10 1 ¯ 4) textures to (0001) texture. Growth regimes for (11 2 ¯ 0), (10 1 ¯ 0), (10 1 ¯ 2), (10 1 ¯ 4) and (0001) textures were depicted as a function of the H2S/CO2 ratio. Examples of grain-boundary and microstructural manipulation of CVD α-Al2O3 layers by applying texture control were presented.

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“…Tooptong et al [2] affirm that the rise in the cutting temperature due to the increase of the cutting speed leads to the degradation of the cutting tool material. Thus, different coating techniques have been developed to improve the resistance of the tool, such as chemical vapor deposition (CVD) [3], physical vapor deposition (PVD) [4,5] and sol-gel [6,7], allowing the fabrication of different coating materials.…”

Section: Introductionmentioning

confidence: 99%

“…One of the main reasons to use aluminium oxide as a tool coating is because it presents a high wear resistance [3,19]. The Al2O3 is characterized by excellent thermal stability, chemical inertness, relatively high hardness at elevated temperatures, and good mechanical and anti-corrosive properties [19,20].…”

Section: Introductionmentioning

confidence: 99%

“…Regardless of the presence of coating on the surfaces of the insert, the authors concluded that the main reason for the poor machinabilities (flank wear) of the CGI (and NGI as well) is that the generated cutting temperatures are much higher than for the FGI. One of the main reasons to use aluminium oxide as a tool coating is because it presents a high wear resistance [3,19]. The Al 2 O 3 is characterized by excellent thermal stability, chemical inertness, relatively high hardness at elevated temperatures, and good mechanical and anti-corrosive properties [19,20].…”

Section: Introductionmentioning

confidence: 99%

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Characterization of Ceramics Coatings Processed by Sol-Gel for Cutting Tools

et al. 2019

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In order to obtain better cutting tool performance, the coatings appear as an alternative in the machining process. The goal of the coating is to improve tribological conditions in the chip-tool and tool-workpiece interfaces. On the other hand, the use of coated tools decreases the wear of the tools. This study discusses the ceramic coatings characterization deposited in WC tools. The Al2O3 and TiO2 films present properties such as thermal stability, chemical inertia, high hardness, and good mechanical properties. These coatings were prepared by sol-gel technology. The results indicated that the multilayer coating presents better adhesion on the substrate. Moreover, lower coefficients of friction were found for the coated tools. The analysis of variance (ANOVA) was used to evaluate the influence of the cutting parameters and tool coating on the cutting force. The lower cutting force was obtained using the multilayer-coated tool. Thus, the sol-gel method appears as a novel technique to deposit coating in the WC tools to improve their performance.

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Effects of reference materials on texture coefficients determined for a CVD α-Al2O3 coating

Cited by 40 publications

References 14 publications

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

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

Influence of Process Conditions on the Growth and Texture of CVD Alpha-Alumina

Characterization of Ceramics Coatings Processed by Sol-Gel for Cutting Tools

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