Study on the crack resistance of CrBN composite coatings via nano-indentation and scratch tests

JOURNAL OF ALLOYS AND COMPOUNDS

卷:708

Article

Wang, Qianzhi^1,2  Zhou, Fei^1,2  Callisti, Mauro³  Polcar, Tomas³  Kong, Jizhou^1,2  Yan, Jiwang⁴ 

[1] Nanjing Univ Aeronaut & Astronaut, State Key Lab Mech & Control Mech Struct, Nanjing 210016, Jiangsu, Peoples R China

[2] Nanjing Univ Aeronaut & Astronaut, Coll Mech & Elect Engn, Nanjing 210016, Jiangsu, Peoples R China

[3] Univ Southampton, Fac Engn & Environm, Natl Ctr Adv Tribol Southampton, Dept Mech Engn, Southampton SO17 1BJ, Hants, England

[4] Keio Univ, Fac Sci & Technol, Dept Mech Engn, Yokohama, Kanagawa 2238522, Japan

关键词: CrBN;    Nano-indentation;    Scratch;    Circumferential crack;    Residual stress;   

DOI  :  10.1016/j.jallcom.2017.03.105

来源: Elsevier

【 摘 要 】

Crack resistance of CrBN coatings in relation to B concentration was investigated via nano-indentation and scratch tests. A nano-composite structure consisting of CrN nano-grains embedded in amorphous BN (a-BN) matrix was observed by transmission electron microscope (TEM). XRD and XPS analyses revealed a decrease of crystallinity in coatings as B content increased from 16.4 to 27.2 at.%, which led to a hardness decrease from 28.9 GPa to 23.6 GPa. All CrBN coatings, regardless of composition, prevented radial cracks due to superior mechanical properties (H/E >= 0.077). However, owing to high compressive stress (3.27-4.74 GPa), circumferential cracks were found along indent edge, and the number of circumferential cracks was proportional to B concentration. Meanwhile, the critical load of initiating crack dropped from 17.9 to 13.4 N when B concentration raised from 12.8 to 22.2 at.%. The results of nano-indentation and scratch tests indicated that the crack resistance of CrBN coatings became poor when the B doping content increased. In here, the CrBN coating with 12.8 at.% B exhibited the best crack resistance. (C) 2017 Elsevier B.V. All rights reserved.

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