Quantong Jiang

Fabrication of g-C3N4/Au/CdZnS Z-scheme photocatalyst to enhance photocatalysis performance

In this study, a sandwich-structured C3N4/Au/CdZnS photocatalyst with Au nanoparticles sandwiched between C3N4 and CdZnS was fabricated. The results showed that there was a 6.3 mmol g−1 increase of hydrogen production for C3N4/Au/CdZnS photocatalyst compared to C3N4/CdZnS in 4 h. The photoinduced I–t curve, electrochemical impedance spectrum (EIS), photogenerated electron lifetime and photoluminescence spectra showed that the photocatalytic ability of the composite was enhanced by anchoring Au as the electron transfer mediator between C3N4 and CdZnS through the Z-scheme charge-carrier transfer mechanism. Au functioned as an electron transition mediator, which could induce a combination between photogenerated electrons and holes in the CdZnS and C3N4, respectively. These photogenerated holes of CdZnS can be involved in the S2−/SO32− oxidation process and the electrons from the C3N4 surface might be involved in the water to hydrogen reduction reaction, thus enhancing the photocatalysis performance of C3N4/Au/CdZnS photocatalyst.

Corrosion behavior of extrusion, under-aged, peaked-aged and over-aged WE93 alloys in NaHSO3 solutions

The corrosion behaviors of extrusion, under-aged, peaked-aged and over-aged WE93 alloys in NaHSO3 solutions were investigated by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The weight loss rates, corrosion morphologies and polarization curves were analyzed. The peak-aged specimen in NaHSO3 salt spray had the highest corrosion rate of 0.9787 mg/cm2/d, while extrusion specimen led to the lowest of 0.2184 mg/cm2/d. The specimens could be arranged in decreasing order of corrosion rates: extrusion<under-aged<over-aged<peak-aged. Polarization curves also gave effective evaluation of corrosion rates in agreement. The NaHSO3 played a great role in the corrosion behaviors of WE93 alloys. The main reasons were that HSO3− developed a reaction: O2+2HSO3−+2e→2HSO42–→2H++2SO42– to generate H+, accelerating the process of corrosion reaction. SO42– stimulated corrosion and led to an autocatalytic type of reaction: Mg2++SO42–+7H2O→MgSO4− 7H2O. XRD characterized that Mg(OH)2 and MgSO4·7H2O were the main corrosion products.

Effect of Heat Treatment on Corrosion Behaviors of Mg-5Y-1.5Nd Alloys

Corrosion behavior of Mg-5Y-1.5Nd alloy was investigated after heat treatment. The microstructure and precipitation were studied by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The weight loss rates of different samples were arranged as T6-24 hT6-6 hT6-14 has-castT4. The open circuit potential (OCP) showed that T4 sample had a more positive potential than that of other samples. The potentiodynamic polarization curves showed that the T6-24 h sample had the highest corrosion current density of 245.362 μAcm−2, whereas the T4 sample had the lowest at 52.164 μAcm−2. The EIS results confirmed that the heat treatment reduced the corrosion resistance for Mg-5Y-1.5Nd alloy, because the precipitations acted as the cathode of electrochemical reactions to accelerate the corrosion process. The corrosion rates of different samples were mainly determined by the amount and distribution of the precipitations. The precipitations played dual roles that depended on the amount and distribution. The presence of the phase in the alloys could deteriorate the corrosion performance as it could act as an effective galvanic cathode. Otherwise, a fine and homogeneous phase appeared to be a better anticorrosion barrier.

The Inhibition Effect of Polyaspartic Acid and Its Mixed Inhibitor on Mild Steel Corrosion in Seawater Wet/Dry Cyclic Conditions

The inhibition effects of polyaspartic acid (PASP) and the mixed inhibitor (50mg/L PASP, 100mg/L Na2WO4, 100mg/L ZnSO4 center dot 7H(2)O) on mild steel corrosion in seawater wet/dry cyclic conditions were studied via weight loss and electrochemical methods. The polarization curves show that the inhibition efficiency is 72.4% in the presence of PASP, and rises up to 92.6% after the addition of the mixted inhibitor. Scanning electron microscopy (SEM), X-ray diffraction and Fourier transform infrared reflection were performed to study the corrosion inhibition effect. According to the results of SEM, the metal surface immersed in the mixed inhibitor was better protected than that in PASP due to the formation of a protective film.

Corrosion behaviour of AZ80 Mg/beryllium–bronze–alloy galvanic couples in typical marine environment

A high-strength AZ80 Mg alloy was prepared via multi-direction forge, thermal extrusion and peak-aged heat treatment. The corrosion behaviour of AZ80 Mg/beryllium–bronze–alloy galvanic couples in a typical marine environment was investigated. Beryllium–bronze alloy (QBe1.7 Cu) acted as cathode, accelerating the corrosion of AZ80 Mg alloy. With the increase in contact areas, the corrosion rates and galvanic effect also increased, and the galvanic potentials moved positively. However, with a prolonged exposure time, the galvanic potentials and current densities decreased. The corrosion products mainly consisted of MgCl2, Mg5(CO3)4(OH)2·5H2O and MgSO4·7H2O. According to the standard of galvanic corrosion sensitivity from the Air Force Materials Laboratory (AFML), AZ80 Mg alloy was not allowed to make contact with QBe1.7 Cu alloy without effective protection.