RESUMEN
Diamond-like carbon (DLC) coatings are effective in protecting the key components of marine equipment and can greatly improve their short-term performance (1.5~4.5 h). However, the lack of investigation into their long-term (more than 200 h) performance cannot meet the service life requirements of marine equipment. Here, three multilayered DLC coatings, namely Ti/DLC, TiCx/DLC, and Ti-TiCx/DLC, were prepared, and their long-term corrosion resistance was investigated. Results showed that the corrosion current density of all DLC coatings was reduced by 1-2 orders of magnitude compared with bare 316L stainless steel (316Lss). Moreover, under long-term (63 days) immersion in a 3.5 wt.% NaCl solution, all DLC coatings could provide excellent long-term corrosion protection for 316Lss, and Ti-TiCx/DLC depicted the best corrosion resistance; the polarization resistances remained at ~3.0 × 107 Ω·cm2 after immersion for 63 days, with more interfaces to hinder the penetration of the corrosive media. Meanwhile, during neutral salt spray (3000 h), the corrosion resistance of Ti/DLC and TiCx/DLC coatings showed a certain degree of improvement because the insoluble corrosion products at the defects blocked the subsequent corrosion. This study can provide a route to designing amorphous carbon protective coatings for long-term marine applications in different environments.
RESUMEN
Blue-phase liquid crystals (BPLCs) are regarded as a potential candidate for the next generation of optical devices, but they appear in a narrow temperature range, which restricts their applicability. The nanoparticle (NP) stabilization of BPLCs, is usually about either simple-cubic BP (BPII) or body-centered-cubic BP (BPI). Hence, NP-stabilized BPIIs and BPIs possessing wide temperature ranges have been scarcely reported. Here, nickel nanoparticles (Ni NPs) were synthesized and introduced into a BPLC. The concentration-dependent temperature range effects of Ni NPs on the BPLC were investigated. A trace amount of Ni NPs could stabilize the BPLC and increase the temperature ranges of BPII and BPI; this is attributable to the Ni NPs tending to be trapped at the joints of the disclination lines, as a result of the elastic interaction, stabilizing the overall lattice structure of the BPLC. When doped with 0.05 wt% Ni NPs, the mixture shows a wider range with 7.7 °C than the range with 5.9 °C of the BPLC without Ni NPs. Meanwhile, the phase sequence and range of the aforementioned phases are reproducible upon heating and cooling, which shows that the BPLCs doped with Ni NPs are thermodynamically stable.