Yuwei Ye

An analysis of the tribological mechanism of GLC film in artificial seawater

The tribological performances of the graphite-like carbon (GLC) films sliding against WC balls in distilled water (DW), artificial seawater (SW) and four types of saline solutions related to seawater were investigated. The GLC film was deposited by magnetron sputtering. The microstructure, mechanical properties and tribological performances of the GLC film were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, nano-indentation and reciprocating ball-on-disk tribo-meter. The results showed that the smooth, dense and hard GLC film with significant sp2-hybridized carbon exhibited good tribological performance with low friction and wear not only in distilled water, but also in seawater. The tribological performance of the GLC film in seawater was closely related to the nature and constitution of seawater, as well as the nature and performance of the counterparts. Bulky wear debris with hard particles would generate a three-body wear regime, which increases the friction coefficient and wear rate of the GLC film slightly in seawater environment. In contrast, the divalent metal salts of seawater can decrease friction and wear between the two contact surfaces. The synergistic effect led to a relatively higher friction coefficient and wear rate of the GLC film against the WC counterpart in seawater than that in distilled water.

Improvement of anticorrosion ability of epoxy matrix in simulate marine environment by filled with superhydrophobic POSS-GO nanosheets

Super-hydrophobicity polyhedral oligomeric silsesquioxane-modified graphene oxide (POSS-GO) was synthesized by one-step reaction between graphene oxide (GO) and aminopropylisobutyl polyhedral oligomeric silsesquioxane (POSS-NH2). Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) spectra indicated that the POSS were successfully connected to the edge and surface of GO nanosheets. Scanning probe microscope (SPM) and transmission electron microscope (TEM) images demonstrated that the POSS-GO with a thickness of 1.58 nm presented a stably dispersion in anhydrous ethanol. Results from electrochemical behaviors showed that the proper incorporation of POSS-GO could availably improve the anticorrosion ability of epoxy based coatings in simulate marine environment (3.5 wt% NaCl solution). The good dispersion of POSS-GO helped to fill the original defect and enhanced the complication of penetration path. The super-hydrophobicity of POSS-GO was beneficial to the reduction of actual contact zone. The synergistic effect of good dispersion and super-hydrophobicity promoted the enhancement of anticorrosion ability for composite coatings.

A study for anticorrosion and tribological behaviors of thin/thick DLC films in seawater

The thin and thick diamond-like carbon (DLC) films were prepared by unbalanced magnetron sputtering technique on 304L stainless steels and (100) silicon wafers. Microstructure, mechanical, corrosion and tribological properties were systematically investigated by SEM, Raman, nanoindenter, scratch tester, modulab electrochemical workstation and R-tec multifunctional tribological tester. Results showed that the adhesion force presented a descending trend with the growth in soaking time. The adhesion force of the thin DLC film with high residual compressive stress (−3.72 GPa) was higher than that of the thick DLC film (−2.96 GPa). During the corrosion test, the thick DLC film showed a higher impendence and a lower corrosion current density than the thin DLC film, which is attributed to the barrier action of large thickness. Compared to bare 304L substrate, the friction coefficients and wear rates of DLC films in seawater were obviously decreased. Meanwhile, the thin DLC film with ideal residual compressive stress, super adhesion force and good plastic deformation resistance revealed an excellent anti-wear ability in seawater.

Effect of interlayer design on friction and wear behaviors of CrAlSiN coating under high load in seawater

In this paper, CrAlSiN coatings with different interlayer designs (without interlayer, Cr interlayer, CrN interlayer and Cr/CrN interlayer) were successfully obtained on 316L stainless steel and single crystal silicon by multi-arc ion plating technique. Coating microstructure, mechanical, anticorrosion and tribological behaviors in artificial seawater were systematically investigated by XRD, SEM, XPS, TEM, nanoindentation, electrochemical workstation and frictional tester system. Results showed that the CrAlSiN layer presented a typical nanocrystalline/amorphous structure, which consisted of CrN, AlN and Si3N4 phases. The Cr/CrN interlayer could obviously improve the adhesion, hardness and toughness of CrAlSiN coating. Compared with single CrAlSiN coating, the corrosion current density of Cr/CrN/CrAlSiN coating system was improved by 2 orders of magnitude and its inhibition efficiency was up to 98.82%. Under high applied load (15 N) condition, the CrAlSiN coating with Cr/CrN interlayer revealed the lowest COF (0.107 ± 0.009) and wear rate (7.3 × 10−8 ± 8.4 × 10−9 mm3 N−1 m−1) in seawater, which primarily attributed to the synergistic effect of ideal adhesion force, outstanding toughness and effectively barrier ability.

Anti-corrosion performance of aniline trimer-containing sol–gel hybrid coatings for mild steel substrate

AbstractNovel electroactive sol–gel hybrid coatings were synthesized by hydrolysis and condensation reaction of tetraethoxysilane (TEOS) and different mass ratios of silane-capped aniline trimer (TSUPQD) on the surface of Q235 steel. Microstructure, thermal stability, and corrosion resistance of as-prepared hybrid coatings were characterized by FTIR, UV–Vis, SEM, TGA, CA measurement, polarization curve, and electrochemical impedance spectroscopy. It could be seen that the icorr value of as-prepared novel coating was markedly lower than those of pure TEOS-based coating and bare substrate. EIS results indicated that the impedance of hybrid coating was higher than that of Q235 steel substrate, indicating the effective protective property for substrate. Meanwhile, the aniline trimer-based hybrid coatings presented much higher impedance after immersion in 3.5 wt% NaCl for 200 h, and the best corrosion performance was acquired when the mass ratio of TEOS/TSUPQD is 100:4. The XRD and SEM analysis of the corrosion product beneath the hybrid coatings showed that the redox catalytic capability of aniline trimer could induce the Q235 substrate to form the passive films which mainly consisted of Fe2O3 and Fe3O4. HighlightsNovel electroactive sol-gel hybrid coatings is successfully achieve in this paper.Corrosion property of aniline trimer containing hybrid coatings is obvious improved.The corrosion property is best when the mass ratio of TESO/TSUPQD is 100:4.The corrosion products mainly contain α-Fe2O3, α-Fe2(OH)3Cl and Fe3O4.