Enhancement of Active Anticorrosion via Ce-doped Zn-Al Layered Double Hydroxides Embedded in Sol-Gel Coatings on Aluminum Alloy

Ce-doped Zn-Al layered double hydroxide（LDH） nanocontainer was synthesized by a co-precipitation method. X-ray diffraction（XRD）, Fourier transform infrared spectroscopy（FT-IR）, scanning electron microscopy（SEM） and transmission electron microscopy（TEM） methods were used for the characterization of the LDH nanocontainer. The anticorrosion activity of the LDH powders embedded in a hybrid sol-gel coating on aluminum alloy 2024 was investigated by electrochemical impendence spectroscopy（EIS）. The results showed that Ce（III） ions were successfully incorporated into LDHs layers. The sol-gel coating modified with Ce-doped Zn-Al LDHs exhibited higher anticorrosion behavior compared with both unmodified and Ce-undoped LDHs containing coatings, which proved the applicability of Ce-doped LDHs in delaying coating degradation and their potential application as nanocontainers of corrosion inhibitors in self-healing coatings.

Droplet transfer behavior of the stainless steel coated electrode with double-layer coating

In this paper, the droplet transfer behavior of the stainless steel coated electrode with double layer coating is researched by means of those experimental methods, such as high speed camera, collecting droplet in water, surfacing on the steel plate et al. The results show that the droplet transfer indexes of coated electrode are mainly controlled by the size of droplet, which affects the transfer behavior of droplet. The distribution characteristic of the droplet size of the electrode affects the numerical relationship among droplet transfer indexes. The metallurgical process of the coated electrode with double layer coating is carried out continuously in different zones. The main reason for the coated electrode with double layer coating gaining excellent usability quality is that the droplets realize the 'quasi flux wall guided transfer pattern'.

Crystallization characteristics of Ni-W-P composite coatings reinforced by CeO_2 and SiO_2 nano-particles

Ni-W-P composite coatings reinforced by Ce O2 and Si O2 nano-particles on the surface of common carbon steels, were prepared by double pulse electrodeposition. The crystallization course was characterized by phase structures, crystallinity, grain sizes and microstructures. The results indicate that as-deposited composite coating is amorphous. Whereas it turns into the crystalline structure with 98.25% crystallinity, and Ni3 P, Ni2 P and Ni5P2 alloy phases precipitate from structures at 400 °C. Thereafter, Ni2 P and Ni5P2 metastable alloy phases turn into Ni3 P stable alloy phase at 500 °C. The crystallization course of the composite coating has finished when being heat-treated at 700 °C. The average sizes of Ni grains increase with the rise of heat treatment temperature from400 °C to 700 °C. Ce O2 and Si O2 nano-particles deposited into Ni-W-P alloys can delay the crystallization course and habit the growth of alloy phases.

Green corrosion inhibitors intercalated Mg:Al layered double hydroxide coatings to protect Mg alloy

Mg alloy was protected with Mg:Al layered double hydroxide(LDH)coating intercalated with three green corrosion inhibitors(sodium benzoate,3-aminopropyltriethoxysilane and 8-hydroxyquinoline).The in-situ hydrothermal approach was adopted to intercalate corrosion inhibitors into Mg:Al LDH coating.The intercalated Mg:Al LDH coating was successfully acquired,and the crystalline structure of Mg:Al LDH coating was verified with X-ray diffraction(XRD).The organic functional groups of corrosion inhibitors were identified with the help of Fourier transform infrared spectroscopy(FTIR)and X-ray photoelectron spectroscopy(XPS).The compact and uniform morphology was confirmed by scanning electron microscopy(SEM).The electrochemical measurement revealed better corrosion resistance of corrosion inhibitorintercalated Mg:Al LDH coatings as compared to that of pristine Mg alloy.The corrosion protection mechanism of corrosion inhibitors was described and unearthed the corrosion inhibitor with the best performance.

BN/SiBCN light-leakage-proof coatings of silica optical fiber for long term sensors at high temperatures

SiBCN and BN/SiBCN light-leakage-proof coatings were prepared on silica optical fibers for sensing applications at high temperatures.Scanning electron microscopy was used to characterize the surface morphology and microstructure of the coated fiber.Mechanical and optical properties of the coated fiber were characterized by Raman,optical and tensile tests.Compared with the original fiber,the tensile strength of Si BCN and BN/Si BCN coated fiber show an increase of about 60%and 90%at room temperature,respectively.In addition,the tensile strength of BN/Si BCN coated silica optical fiber was increased by about 42%at 700°C.It has been found that the improvement of the strength of BN/Si BCN coated silica optical fiber is related to the healing of defects and residual compressive stress in fibers.From the light transmittance performance of the coated fiber,it was found that BN/Si BCN double coating could be an ideal total reflection solution to protect silica optical fiber from light leakage during high temperature sensing operation.

Design and preparation of frequency doubling antireflection coating with different thicknesses of interlayer for LiB3O5 crystal

Design and preparation of frequency doubling antireflection coating with different thicknesses of interlayer were investigated for LIB3O5 （LBO） substrate. The design was based on the vector method. The thickness of the inserted SiO2 interlayer could be changed in a wide range for the four-layer design with two zeros at 1064 and 532 nm. The coatings without any interlayer and with 0.1 quarter-wave （λ/4）, 0.3 λ/4, 0.5 λ/4 SiO2 interlayer were deposited respectively on LBO by using electron beam evaporation technique. All the prepared coatings with SiO2 interlayer indicated satisfying optical behavior. This expanded our option for the thickness of an interlayer when coating on LBO substrate. The prepared films with SiO2 interlayer showed better adhesion than that without any interlayer. The thickness of the interlayer affected the adhesion, the adhesion for the coating with 0.5 λ/4 SiO2 interlayer was not as good as the other two.

Acoustic reflection of rib-stiffened double plates coated with a viscoelastic layer

To predict sound-absorbing performance of anechoic materials,the acoustic reflection problem of a viscoelastic layer backed with periodically rib-stiffened infinite double plates is studied in this paper.The reason why structural theories of plates are not applicable to viscoelastic plates is explained through comparing dispersion and attenuation curves of flexural waves with those of Lamb waves.As a result,（visco-）elastic theory is adopted to deal with（visco-）elastic plates,and ribs are treated by structural theories of plates.The coupling between ribs and plates are solved by Hull＇s method,and solution of the reflected field is obtained.The accuracy of present method is validated by comparing with the results by the structural theories of plates.The influence of a backing on the acoustic reflection of the viscoelatic layer is analyzed by computing reflection coefficients.Performances of different viscoelastic materials are evaluated by the average reflection coefficients.The computational results show that,influence of a backing on the acoustic reflection cannot be suppressed by the viscoelastic materials in low frequencies.The resonance is determined by the coupling of the fluid layer and the double plates.And ribs,which are coupled with the double plates,mainly reduce the acoustic reflection.

Fabrication of narrow pulse passively Q-switched self-stimulated Raman laser with c-cut Nd:GdVO_4

Combining the self-stimulated Raman scattering technology and saturable absorber of Cr^(4+):YAG, a 1.17 μm c-cut Nd:GdVO_4 picosecond Q-switched laser is demonstrated in this paper. With an incident pump power of 10 W, the Q-switched laser with average power of 430 mW for 1.17 μm, pulse width of 270 ps, repetition rate of 13 kHz and the first order Stokes conversion efficiency of 4.3% is obtained. The Q-switched pulse width can be the narrowest in our research. In addition, the yellow laser at 0.58 μm is also achieved by using the LiB_3O_5 frequency doubling crystal.