TY - JOUR
T1 - Disclosing mechanical and specific structural characteristics of thick and adherent nanodiamond composite hard coating deposited on WC−Co substrates
AU - Murasawa, Koki
AU - Diab, Mohamed R.
AU - Atta, Hoda
AU - Naragino, Hiroshi
AU - El-Shaer, Abdelhamid
AU - Yoshitake, Tsuyoshi
AU - Egiza, Mohamed
N1 - Publisher Copyright:
© 2024 The Authors
PY - 2024/8
Y1 - 2024/8
N2 - Nanodiamond composite (NDC) films, with a notable hardness of 65 GPa and a substantial thickness of 10 µm, were successfully fabricated on unheated WC−Co substrates using cathodic arc plasma deposition (CAPD) technology. Raman and synchrotron-based structural analysis, comparing NDC films with similarly hard tetrahedral amorphous carbon (ta-C) films and chemical vapor deposition (CVD) diamond, unveiled distinctive features. Visible Raman spectroscopy highlighted NDC's unique nanostructured composition, characterized by nanodiamond grains embedded in an amorphous carbon matrix, resulting in a high fraction of C−C sp3 bonds (70 %) and intense σ* C−C resonance contributing to its observed hardness. The small size of diamond crystals induced numerous grain boundaries, as evident through intense t-PA Raman peaks, effectively suppressing internal stress to 2.77 GPa and enabling the deposition of an impressive thickness (10 µm), surpassing the thinness of hard ta-C (< 1 µm). Despite the substantial thickness, NDC films demonstrated remarkable films-substrate adhesion, with no delamination and minimal spallation, in contrast to observed buckling and delamination in CVD diamond during Rockwell testing at various loads (60 Kg and 100 Kg). Additionally, NDC films maintained a stable and low coefficient of friction (≤ 0.1) against an Al2O3 counter-body, compared to the higher coefficient (≥ 0.25) of the bare WC-Co substrate. Furthermore, NDC deposition boasted a rapid rate (3.5 µm/h), significantly exceeding both ta-C and diamond coatings, enhancing its practical applicability. Significantly, the deposition process for NDC films stands out for its environmental friendliness and cost-effectiveness, involving no external heating, chemical reactions, chemical etching of Co, or nanodiamond seeding. The findings underscore the exceptional potential of NDC as a strong competitor to hard ta-C and CVD diamond coatings, especially in advanced cutting tool applications.
AB - Nanodiamond composite (NDC) films, with a notable hardness of 65 GPa and a substantial thickness of 10 µm, were successfully fabricated on unheated WC−Co substrates using cathodic arc plasma deposition (CAPD) technology. Raman and synchrotron-based structural analysis, comparing NDC films with similarly hard tetrahedral amorphous carbon (ta-C) films and chemical vapor deposition (CVD) diamond, unveiled distinctive features. Visible Raman spectroscopy highlighted NDC's unique nanostructured composition, characterized by nanodiamond grains embedded in an amorphous carbon matrix, resulting in a high fraction of C−C sp3 bonds (70 %) and intense σ* C−C resonance contributing to its observed hardness. The small size of diamond crystals induced numerous grain boundaries, as evident through intense t-PA Raman peaks, effectively suppressing internal stress to 2.77 GPa and enabling the deposition of an impressive thickness (10 µm), surpassing the thinness of hard ta-C (< 1 µm). Despite the substantial thickness, NDC films demonstrated remarkable films-substrate adhesion, with no delamination and minimal spallation, in contrast to observed buckling and delamination in CVD diamond during Rockwell testing at various loads (60 Kg and 100 Kg). Additionally, NDC films maintained a stable and low coefficient of friction (≤ 0.1) against an Al2O3 counter-body, compared to the higher coefficient (≥ 0.25) of the bare WC-Co substrate. Furthermore, NDC deposition boasted a rapid rate (3.5 µm/h), significantly exceeding both ta-C and diamond coatings, enhancing its practical applicability. Significantly, the deposition process for NDC films stands out for its environmental friendliness and cost-effectiveness, involving no external heating, chemical reactions, chemical etching of Co, or nanodiamond seeding. The findings underscore the exceptional potential of NDC as a strong competitor to hard ta-C and CVD diamond coatings, especially in advanced cutting tool applications.
KW - Cathodic arc
KW - DLC
KW - Hard coatings
KW - Nanocomposite films
KW - Raman
KW - WC−Co
UR - http://www.scopus.com/inward/record.url?scp=85198728008&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85198728008&partnerID=8YFLogxK
U2 - 10.1016/j.mtcomm.2024.109839
DO - 10.1016/j.mtcomm.2024.109839
M3 - Article
AN - SCOPUS:85198728008
SN - 2352-4928
VL - 40
JO - Materials Today Communications
JF - Materials Today Communications
M1 - 109839
ER -