Fracture toughness evaluation of nanocrystalline, bilayer, gradient and gradient-multilayer diamond films via nanoindentation

IF 4.3 3区材料科学 Q2 MATERIALS SCIENCE, COATINGS & FILMS

Diamond and Related Materials Pub Date : 2025-03-25 DOI:10.1016/j.diamond.2025.112238

Yanming Liu , Dingkun Li , Haozhe Song , Xiao Zhao , Bo Pang , Lusheng Liu , Tianwen Hu , Nan Huang

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Abstract

Diamond films are widely used as tool coatings for machining hard materials, yet balancing hardness and fracture toughness remains challenging. Here, nanocrystalline (NCD), bilayered multilayer (2L-M), gradient (G), and gradient- multilayer (G-M) diamond films were deposited by hot filament chemical vapor deposition (HFCVD). Fracture toughness of these four diamond films was evaluated via nanoindentation following Anstis's equation. Results showed that 2L-M films had the lowest fracture toughness suffering from its sharp interfaces with high sp² phase content and stress concentrations, whereas G films obtained improved toughness through gradual grain size reduction. Notably, the fracture toughness of G-M film reached 9.62 MPa·m^1/2 with highest hardness of 71.8 GPa, even surpassing traditional NCD films. This enhancement was attributed to the novel gradient-multilayer architecture, which improved interfacial integrity, reduced residual stress at interfaces through moderate transitions, and suppressed crack propagation by combining gradually decreasing grain sizes in the MCD layer with multiple interfaces. The work demonstrates that gradient-multilayer designs effectively reconcile high hardness and fracture toughness in diamond films, offering a viable strategy for advanced tool-coating applications.

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来源期刊

Diamond and Related Materials 工程技术-材料科学：综合

CiteScore

6.00

自引率

14.60%

发文量

702

审稿时长

2.1 months

期刊介绍： DRM is a leading international journal that publishes new fundamental and applied research on all forms of diamond, the integration of diamond with other advanced materials and development of technologies exploiting diamond. The synthesis, characterization and processing of single crystal diamond, polycrystalline films, nanodiamond powders and heterostructures with other advanced materials are encouraged topics for technical and review articles. In addition to diamond, the journal publishes manuscripts on the synthesis, characterization and application of other related materials including diamond-like carbons, carbon nanotubes, graphene, and boron and carbon nitrides. Articles are sought on the chemical functionalization of diamond and related materials as well as their use in electrochemistry, energy storage and conversion, chemical and biological sensing, imaging, thermal management, photonic and quantum applications, electron emission and electronic devices. The International Conference on Diamond and Carbon Materials has evolved into the largest and most well attended forum in the field of diamond, providing a forum to showcase the latest results in the science and technology of diamond and other carbon materials such as carbon nanotubes, graphene, and diamond-like carbon. Run annually in association with Diamond and Related Materials the conference provides junior and established researchers the opportunity to exchange the latest results ranging from fundamental physical and chemical concepts to applied research focusing on the next generation carbon-based devices.