Sustainable super-hard and thick nanodiamond composite film deposited on cemented carbide substrates with an interfacial Al-interlayer.

Super-hard nanodiamond composite (NDC) films, synthesized via cathodic arc plasma deposition on unheated WC−Co substrates, offer an eco-friendly solution for cutting tools. A 100 nm-thick Al-interlayer mitigates Co catalytic effects, improving adhesion and yielding smooth and dense 10 µm-thick films at a deposition rate of 3.3μm/hr. These grain-boundary-rich nanostructured films, with an impressive 58 GPa hardness attributed to a substantial 70% C sp3 fraction, prove optimal for hard coatings. The Al-interlayer effectively suppresses Co catalytic effects, forming a dense Al-oxide layer, enhancing film hardness and adhesion (Lcr=18.6N). NDC films present a promising eco-friendly option for high-performance hard coatings

Wear-resistant and adherent nanodiamond composite thin film for durable and sustainable silicon carbide mechanical seals.

In response to environmental concerns, there is a growing demand for durable and sustainable mechanical seals, particularly in high-risk industries like chemical, petroleum, and nuclear sectors. This work proposes augmenting the durability and sustainability of silicon carbide (SiC) ceramic seals with the application of a nanodiamond composite (NDC) film through coaxial arc plasma deposition (CAPD) in a vacuum atmosphere. The NDC coating, with a smooth surface roughness of Ra = 60 nm as substrate, demonstrated a thickness of 1.1 μm at a deposition rate of 2.6 μm/hr. NDC film has demonstrated exceptional mechanical and tribological characteristics, such as a hardness of 48.5 GPa, Young’s modulus of 496.7 GPa, plasticity index (H/E) of 0.098, and fracture toughness of H3/E2 = 0.46 GPa, respectively. These NDC films showcased commendable adhesion strength (> 60 N), negligible wear, and low friction (≤ 0.18) during dry sliding against a SiC counter material. Raman analysis has confirmed the nanocomposite structure of NDC film, emphasizing the role of highly energetic carbon ions in enhancing film adhesion by forming SiC intermetallic compounds at the interface through the diffusion of silicon atoms from the substrate into the films. The abundance of grain boundaries and rehybridization of carbon sp3 to sp2 bonding is perceived to improve tribological performance. CAPD excels in synthesizing long-life eco-friendly NDC coatings for durable and sustainable mechanical seals, featuring smooth surfaces, superior adhesion, outstanding hardness, and wear resistance, making them high potential candidates for various tribological applications

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

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

Identification of MMP-9 as a biomarker for detecting progression of chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is a complex immunological disease with multiple pathological features that is primarily induced by smoking together with additional genetic risk factors. COPD is frequently underdiagnosed; forced expiratory volume in the first second (FEV1) is considered to be the main diagnostic measure for COPD, yet it is insufficiently sensitive to monitor disease progression. Biomarkers capable of monitoring COPD progression and severity are needed. In this report, we evaluated matrix metalloproteinase-9 (MMP-9) as an early marker for the detection and staging of COPD, by assessing the mRNA levels of MMP-9 in peripheral blood samples collected from 22 COPD patients, 6 asymptomatic smokers and 5 healthy controls. Our results demonstrate that the mRNA levels of MMP-9 increased more than two-folds in severe COPD relative to non-COPD smokers or moderate COPD groups. Moreover, in the very severe COPD group, MMP-9 mRNA levels showed a 4-fold increase relative to the non-COPD smokers or the moderate COPD groups, while there was a mild increase (~ 40%) when compared to the severe COPD group. Taken together, our results suggest that MMP-9 serves as a biomarker for the grade and severity of COPD.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Effects of Air Exposure on Hard and Soft X-ray Photoemission Spectra of Ultrananocrystalline Diamond/Amorphous Carbon Composite Films

Hard X-ray photoemission spectroscopy (HAXPES) was employed for the structural evaluation of ultrananocrystalline diamond/amorphous carbon (UNCD/a-C) composite films deposited on cemented carbide substrates, at substrate temperatures up to 550 °C by coaxial arc plasma deposition. The results were compared with those of soft X-ray photoemission spectroscopy (SXPES). Since nanocrystalline diamond grains are easily destroyed by argon ion bombardment, the structural evaluation of UNCD/a-C films, without the argon ion bombardment, is preferable for precise evaluation. For samples that were preserved in a vacuum box after film preparation, the sp3 fraction estimated from HAXPES is in good agreement with that of SXPES. The substrate temperature dependencies also exhibited good correspondence with that of hardness and Young’s modulus of the films. On the other hand, the sp3 fraction estimated from SXPES for samples that were not preserved in the vacuum box had an apparent deviation from those of HAXPES. Since it is possible for HAXPES to precisely estimate the sp3 fraction without the ion bombardment treatment, HAXPES is a feasible method for UNCD/a-C films, comprising nanocrystalline diamond grains

Fabrication of Ultrananocrystalline Diamond/Nonhydrogenated Amorphous Carbon Composite Films for Hard Coating by Coaxial Arc Plasma Deposition

Ultrananocrystalline diamond (UNCD)/nonhydrogenated amorphous carbon (a-C) composite (UNCD/a-C) films were deposited on cemented carbide (WC-Co) substrates by coaxial arc plasma deposition (CAPD). To suppress the graphitization induced by Co in the WC-Co, the film deposition was carried out on unheated substrates. The hardness and Young’s modulus were 51.3 GPa and 520.2 GPa, respectively. These values are comparable or rather larger than those of UNCD/a-C films deposited on other substrates such as Si, which implies that the graphitization of UNCD/a-C hardly occurs. Surprisingly, UNCD/a-C films could be deposited at the maximum film thickness of approximately 3 μm in spite of the room temperature growth. The internal compress-stress of the film is approximately 4.5 GPa, which is evidently smaller than that of comparably hard a-C films. The existence of a large number of grain boundaries in the films, which is structural specific to UNCD/a-C, might play an important role in the release of an internal stress in the film. It was experimentally demonstrated that UNCD/a-C films prepared by CAPD are potential hard coating materials for WC-Co