Junying Hao

A Near‐Frictionless and Extremely Elastic Hydrogenated Amorphous Carbon Film with Self‐Assembled Dual Nanostructure

A highly crosslinking network combined with a fullerene-like structure is disclosed in a hydrogenated amorphous carbon film. The very soft carbon film exhibits super-low friction and excellent wear resistance even under a Hertzian contact pressure comparable to its hardness under vacuum, which is an extraordinary tribological behavior in the filed of solid lubrication films or coatings.

Properties of TiN/TiCN multilayer films by direct current magnetron sputtering

In this work, a TiN/TiCN multilayer film was deposited by direct current magnetron sputtering. Its thickness was about 9675 nm and the bilayer numbers were 10. The composition, crystalline structure and amorphous carbon (a-C) phase of the film were investigated by x-ray photoelectron spectroscopy, x-ray diffraction and Raman spectroscopy. Field emission scanning electron microscopy was employed to observe the inner structure of the film. The TiCN layer exhibited a glass-like structure and the TiN layer presented a columnar structure. The adhesion force between the film and the substrate was 37.8 N determined by scratch tests. The hardness of the uppermost TiCN layer and the total film was 34.22 GPa and 27.22 GPa obtained by nano-indentation tests, respectively. In addition, the TiN/TiCN multilayer thick film showed different types of tribological behaviour against Si3N4 balls and steel balls. The mean coefficient of friction and the wear rate of the film were about 0.14 and 1.15 × 10−6 mm3 N−1 m−1 when the film slid against Si3N4 balls for 1 h.

Superlow friction of titanium/silicon codoped hydrogenated amorphous carbon film in the ambient air

Titanium/silicon codoped hydrogenated carbon film was deposited on the n-Si (100) substrates by reactive magnetron sputtering Ti80Si20 target in a mixture of argon and methane. Microstructure of the film was investigated using x-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, Raman spectroscopy, and attenuated total reflectance Fourier transform infrared spectroscopy. The investigations have revealed that the film has an amorphous structure and consists of high sp2 hybridized carbon atoms and bonding hydrogen atoms. The mechanical and tribological properties were evaluated using a nanoindentor and a ball-on-disk tribometer, respectively. The film exhibits hardness of 9.6 GPa, high elastic recovery of 73.0% and high H/E ratio of 0.156. Most significant, the superlow friction (μ<0.01) and special low wear rate (2.4×10−7 mm3 N−1 m−1) was observed in ambient air with 40% relative humidity. Combining the results of scanning electron microscopy and Raman analyses of the worn su...

Preparation of superior lubricious amorphous carbon films co-doped by silicon and aluminum

Silicon (Si) and aluminum (Al) co-doped amorphous carbon films ((Si, Al)–C:H) were deposited on Si and stainless steel substrates by radio frequency (13.56 MHz) magnetron sputtering. The Al and Si were found to jointly regulate the hybridized carbon bonds. Mechanical properties of the films were detected by nano-indention and scratch tests. The nano-indention results revealed that all the samples exhibited good elastic recovery rate, among which the highest one was beyond 84%. Besides co-regulating the hybridizations of carbon, the co-doped Si and Al also had a common regulation on the mechanical and tribological properties. Especially, the film containing 1.6 at. % of Si and 0.9 at. % of Al showed a super-low friction (< 0.01) and a superior wear resistance in ambient air.

Influence of flow ratio on mechanical and tribological properties of hydrogenated carbon nitride films prepared by DC-RF-PECVD

Amorphous hydrogenated carbon nitride (a-CN : H) films were deposited onto silicon (n-100) substrates by dual direct current radio frequency plasma enhanced chemical vapour deposition with CH 4 and N 2 as feedstock at different ratios. The composition and surface morphology of the films were characterized by means of x-ray photoelectron spectroscopy, Raman spectroscopy and atomic force microscopy; while the mechanical and tribological properties of the films were evaluated using nano-indentation and the UMT test system. It was found that the deposition rate of the films decreased significantly but the N/C ratio, the surface roughness and the I D /I G ratio of the films increased as the N 2 /CH 4 flow ratio increased. The nano-hardness and adhesion strength of the films to the silicon substrate sharply increased at first and then decreased with increasing N 2 /CH 4 flow ratio. Moreover, the wear resistance of the films varied with the N 2 /CH 4 flow ratio. The structure transformation from an sp 3 -like to sp 2 -like carbon-nitrogen network in the deposited films was also revealed.

Microstructure and properties of nc-TiC/a-C∶H films deposited by radio frequency reactive sputtering

Abstract Amorphous carbon films containing titanium carbide (nc-TiC/a-C∶H) were deposited onto n-type silicon (100) by radio frequency reactive sputtering titanium target in an Ar–CH4 mixed atmosphere. The composition and microstructure of the films were characterised by means of X-ray photoelectron spectroscopy, field emitted SEM, XRD and Raman spectra. The mechanical and tribological properties of the films were measured by a nanoindentation tester and a ball-on-disc UMT–2MT tribometer. By adjusting the CH4 flowrate, Ti content in the films could be controlled, and a transition in structures of the films from loose polymer-like to glassy and dense nanostructure was observed. The density of coatings was improved by the introduction of TiC nanocrystalline particles. The mechanical and lubricious properties were different accordingly.

Substrate temperature effect on the microstructure and properties of (Si, Al)/a-C:H films prepared through magnetron sputtering deposition

Hydrogenated amorphous carbon films codoped with Si and Al ((Si, Al)/a-C:H) were deposited through radio frequency (RF, 13.56 MHz) magnetron sputtering on Si (100) substrate at different temperatures. The composition and structure of the films were investigated by means of X-ray photoelectron spectroscopy (XPS), TEM, and Raman spectra, respectively. The substrate temperature effect on microstructure and mechanical and tribological properties of the films was studied. A structural transition of the films from nanoparticle containing to fullerene-like was observed. Correspondingly, the mechanical properties of the films also had obvious transition. The tribological results in ambient air showed that high substrate temperature (>573 K) was disadvantage of wear resistance of the films albeit in favor of formation of ordering carbon clusters. Particularly, the film deposited at temperature of 423 K had an ultralow friction coefficient of about 0.01 and high wear resistance.

Tribological behavior of Fe3Al-60 wt.% Fe3AlC0.5 composite under air and vacuum conditions

Abstract The tribological behavior of Fe3Al composite with 60 wt.% Fe3AlC0.5 under air and vacuum was studied. The composite exhibited a lower wear rate but somewhat higher friction coefficient under air than vacuum. The wear rates increased and the friction coefficients decreased with increasing the applied load under both conditions. The sub-layer of the worn surface under vacuum suffered from severe plastic deformation. This was not the case under air due to protection by surface oxide films. The dominant wear mechanisms were plastic deformation and adhesion under vacuum and oxidative wear and slight delamination under air.

Influence of Applied Bias Voltage on the Composition, Structure, and Properties of Ti:Si-Codoped a-C:H Films Prepared by Magnetron Sputtering

The titanium- and silicon-codoped a-C:H films were prepared at different applied bias voltage by magnetron sputtering TiSi target in argon and methane mixture atmosphere. The influence of the applied bias voltage on the composition, surface morphology, structure, and mechanical properties of the films was investigated by XPS, AFM, Raman, FTIR spectroscopy, and nanoindenter. The tribological properties of the films were characterized on an UMT-2MT tribometer. The results demonstrated that the film became smoother and denser with increasing the applied bias voltage up to −200 V, whereas surface roughness increased due to the enhancement of ion bombardment as the applied bias voltage further increased. The sp3 carbon fraction in the films monotonously decreased with increasing the applied bias voltage. The film exhibited moderate hardness and the superior tribological properties at the applied bias voltage of −100 V. The tribological behaviors are correlated to the H/E or H3/E2 ratio of the films.

Tailoring the Tribocorrosion and Antifouling Performance of (Cr, Cu)-GLC Coatings for Marine Application

Doped graphite-like coating (GLC) has aroused great interest as one of the most promising protective materials in marine applications. However, there is a lack of systematic research on the tribocorrosion and antifouling performance of doped GLC coatings in harsh marine environments. Herein, a multifunctional (Cr, Cu)-GLC coating with combined antifouling and tribocorrosion properties was prepared via a magnetron sputtering method. The experimental results indicate that the resultant coatings changed from a dense structure to a loose columnar structure with the increment of Cr and Cu doping amount. At the same time, the hardness of the coating gradually decreases, but the contact angle between coating and seawater gradually increases. The algae adhesion test reveal that the algae density on the surface of the (Cr, Cu)-GLC coating decreases from about 565 to 70/mm2 as the amount of doping increased. However, on the contrary, the friction coefficient of the coating under OCP condition increases from 0.06 to about 0.35. Overall, the mild doped (Cr, Cu)-GLC coating exhibits the best comprehensive properties, combining antifouling and tribocorrosion properties. The corresponded mechanisms are discussed in terms of the coating microstructure, antifouling, and tribocorrosion behavior.