TY - JOUR
T1 - An investigation on the crack resistance of CrN, CrBN and CrTiBN coatings via nanoindentation
AU - Wang, Qianzhi
AU - Zhou, Fei
AU - Zhou, Zhifeng
AU - Li, Lawrence Kwok Yan
AU - Yan, Jiwang
N1 - Funding Information:
This work has been initiated by a Japan-China joint research project and partially supported by a research grant from Keio Leading-edge Laboratory of Science and Technology (KLL) in Keio University . In addition, this work has been supported by National Natural Science Foundation of China (Grant No. 51375231 ), Scientific Research Foundation for the Introduced Talent , Nanjing University of Aeronautics and Astronautics (Grant No. 1005-YAH16043 ) and the Natural Science Foundation of Jiangsu Province (Grant No. BK20170794 ). We would like to acknowledge them for their financial support.
Publisher Copyright:
© 2017 Elsevier Ltd
PY - 2017/11
Y1 - 2017/11
N2 - This study is to pinpoint the effect of B doping and Ti-B co-doping on the crack resistance of CrN coating via nanoindentation. X-ray photoelectron spectroscopy (XPS) indicated that, besides Cr-N bond, B-N bond formed in CrBN coating while B-N and Ti-N bonds formed in CrTiBN coating. Owing to the stronger B-N, Ti-N bonds and nano-composite structure, CrBN and CrTiBN coatings presented a much higher hardness of 25.2 and 27.4 GPa than CrN coating (15.2 GPa). More importantly, the improved mechanical properties (H/E ≥ 0.083, We ≥ 78.6%) and high compressive stress (σ ≥ 3.53 GPa) of CrBN and CrTiBN coatings prevented them from encountering radial cracks under 700 mN. In contrast, CrN coating suffered radial cracks even under 400 mN. However, circumferential cracks emerged on CrBN and CrTiBN coatings under a combination effect of high compressive stress, poor plasticity (Rp) and low hardness ratio between substrate and coatings (Hs/H). It was indicated that B doping and Ti-B co-doping could improve the resistance of CrN coating to radial crack, but weaken its resistance to circumferential crack. In addition, more circumferential cracks found on CrTiBN coating demonstrated that an extra Ti doping would further deteriorate the crack resistance of CrBN coating.
AB - This study is to pinpoint the effect of B doping and Ti-B co-doping on the crack resistance of CrN coating via nanoindentation. X-ray photoelectron spectroscopy (XPS) indicated that, besides Cr-N bond, B-N bond formed in CrBN coating while B-N and Ti-N bonds formed in CrTiBN coating. Owing to the stronger B-N, Ti-N bonds and nano-composite structure, CrBN and CrTiBN coatings presented a much higher hardness of 25.2 and 27.4 GPa than CrN coating (15.2 GPa). More importantly, the improved mechanical properties (H/E ≥ 0.083, We ≥ 78.6%) and high compressive stress (σ ≥ 3.53 GPa) of CrBN and CrTiBN coatings prevented them from encountering radial cracks under 700 mN. In contrast, CrN coating suffered radial cracks even under 400 mN. However, circumferential cracks emerged on CrBN and CrTiBN coatings under a combination effect of high compressive stress, poor plasticity (Rp) and low hardness ratio between substrate and coatings (Hs/H). It was indicated that B doping and Ti-B co-doping could improve the resistance of CrN coating to radial crack, but weaken its resistance to circumferential crack. In addition, more circumferential cracks found on CrTiBN coating demonstrated that an extra Ti doping would further deteriorate the crack resistance of CrBN coating.
KW - Circumferential crack
KW - Cr-Ti-B-N
KW - Mechanical properties
KW - Nanoindentation
KW - Radial crack
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U2 - 10.1016/j.vacuum.2017.08.041
DO - 10.1016/j.vacuum.2017.08.041
M3 - Article
AN - SCOPUS:85028750959
SN - 0042-207X
VL - 145
SP - 186
EP - 193
JO - Vacuum
JF - Vacuum
ER -