Eco-friendly thick and wear-resistant nanodiamond composite hard coatings deposited on WC–Co substrates.

Diab, Mohamed Ragab; Egiza, Mohamed; Murasawa, Koki; Naragino, Hiroshi; El-Shaer, Abdelhamid; Yoshitake, Tsuyoshi

Abstract

Nanodiamond composite (NDC) films, synthesized using an environmentally friendly PVD coaxial arc plasma deposition technique on commercial cemented carbide (Co6 wt%) substrates without the need for substrate heating, chemical etching of Co, and chemical gases. These NDC coatings, crafted under specific discharge power conditions (5.2 J/pulse, 120 V, and 1 Hz), with or without a substrate biasing (−100V, 40kHz, and 35% duty cycle), exhibit a distinctive nanostructure characterized by nanodiamond grains embedded in an amorphous carbon (a-C) matrix. Highlighting remarkable mechanical characteristics attributed to highly energetic ejected carbon ion. The coatings boast high hardness (H = 65–82 GPa), Young's modulus (E = 688–780 GPa), plasticity index (H/E = 0.094–0.105), and brittle fracture resistance (H3/E2 = 0.58–0.9 GPa). Additionally, these NDC films manifest a substantial thickness of 7 μm due to low internal stress, along with superior adhesion, anti-wear resistance, and a low friction coefficient (0.1–0.09) through dry sliding against an Al2O3 counterpart. Raman analysis substantiates the nanocomposite structure of the film, underscoring the influential role of biasing in enhancing the characteristics of these environmentally friendly and wear-resistant NDC coatings. Nevertheless, the application of a negative bias led to increased internal stress levels (1.28 to 4.53 GPa), adversely impacting the adhesion between the film and substrate, resulting in a decrease from HF3 to HF6 as per Rockwell C indentation. NDC coatings hold significant potential for extending the lifespan of cutting tools and improving overall machining performance.

Citation

DIAB, M.R., EGIZA, M., MURASAWA, K., NARAGINO, H., EL-SHAER, A. and YOSHITAKE, T. 2024. Eco-friendly thick and wear-resistant nanodiamond composite hard coatings deposited on WC–Co substrates. Surface and coatings technology [online], 479, article number 130517. Available from: https://doi.org/10.1016/j.surfcoat.2024.130517

• Journal Article Type: Article
• Acceptance Date: Feb 5, 2024
• Online Publication Date: Feb 6, 2024
• Publication Date: Mar 15, 2024
• Deposit Date: Feb 22, 2024
• Publicly Available Date: Feb 7, 2025
• Journal: Surface and coatings technology
• Print ISSN: 0257-8972
• Electronic ISSN: 1879-3347
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 479
• Article Number: 130517
• DOI: https://doi.org/10.1016/j.surfcoat.2024.130517
• Keywords: Arc plasma deposition; Nanocomposite; Negative bias; Mechanical properties; Hard coatings; Wear resistance
• Public URL: https://rgu-repository.worktribe.com/output/2249807