NiAl phase is a typical Hume-Rothery compound with excellent oxidation-resistant property so this phase is often used as master phase of aluminide coatings. Because diffusion phenomena is extremely important for formation and degradation of aluminide coatings, it is possible to understand the natural characteristics of the diffusion phenomena controlling the degradation of aluminide coatings through chemical diffusion coefficients of NiAl phase obtained. This work reviews chemical diffusion coefficients of NiAl phase in the Ni-Al binary system, the Ni-Cr-Al ternary system, and the Ni-Co-Cr-Al quaternary system. Based on the obtained chemical diffusion coefficients of NiAl phase, the mobility database of NiAl phase is set up using the PARRAT module in the commercial DICTRA software for determining chemical diffusion coefficients of NiAl phase in the multiphase systems.

Boron-doping is a useful method to improve the antioxidation ability of carbon materials. Three boron-doping methods including gas boron-doping, liquid boron-doping, and solid boron-doping have been reported in this paper. The application of microwave in boron-doping is also described. The application scope and the mechanism of different boron-doping methods are summarized. Finally, the prospect of boron-doping to increase the antioxidation ability of carbon materials is previewed.

Stainless steel materials are widely used in coastal infrastructure. These infrastructure is apt to corrode under severe marine environment. Several common mechanisms for stress corrosion cracking are introduced in this paper, as well as some main methods usually used to investigate the phenomenon of stress corrosion cracking and hydrogen embrittlement. Meanwhile, feasible method to control the stress corrosion cracking of stainless steel was proposed.

Evolution mechanism of pitting of Al clad 7075 and 2024 aluminium alloy in coastal environment was investigated by long-term field testing and laboratory-accelerated test. Corrosion morphologies, elemental distribution and corrosion potential were observed and analyzed by SEM, EDS and electrochemical analysis system. The result of EDS spectrum showed that the outer cladding layer only revealed the presence of Al and Zn, while the inner cladding layer still showed certain Mg content besides Al and Zn. A small quantity of Mg enhanced corrosion resistance of the inner cladding layer, which results that the cladding has not been penetrated by pitting after 20 years exposure in coastal environment. Moreover, the shape of those pits in coastal environment was wide and shallow in field testing and laboratory-accelerated test.

The diffusing behavior of water through epoxy coating under ordinary pressure (1 atm) and high hydrostatic pressures in deep ocean (35 atm) was investigated by traditional gravimetric method and electrochemical impedance spectroscopy (EIS). The corresponding diffusion coefficients were calculated and the effect of hydrostatic pressures on kinetics of water adsorption was also analyzed. The results showed that high hydrostatic pressure accelerated the diffusion process of water through organic coating, and the diffusion mechanism had been changed from ideal Fick diffusion under 1atm to S type adsorption non-ideal Fick diffusion under 35 atm. The parameters for diffusion kinetics, including diffusion velocity, saturation time and saturated percent of water adsorption were significantly different under two environments. The changes of parameters relevant to the barrier property of epoxy coating with immersion time were also severer under high pressure, including the coating capacitance C_c, coating resistance R_c, and break-point frequency f_b, resulting in coating failure before its lifetime.

The effects of laser parameters at a constant laser power (1600W) on the corrosion behavior of 17-4PH stainless steel were investigated in 3.5% NaCl solution by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) technique, combined with optical microscopy and scanning electron microscopy (SEM) observation. The results showed that sample A, which was treated by laser surface melting process with light-absorption X and scanning speed of 6 mm/s, possessed the highest corrosion resistance. The results also demonstrated that the homogeneous microstructure was obtained only when the light-absorption and the scanning speed matched well (such as the light-absorption X and scanning speed 6 mm/s), leading the enhancement of the corrosion resistance; otherwise the heterogeneous would be obtained (such as the light-alsorlant Y and scanning speed 6 mm/s), leading to the degradation of the corrosion resistance and the material would suffer serious pitting corrosion when it was used in the corrosive environment.

Scanning electron microscope（SEM），X-ray diffraction（XRD），X-ray photoelectron spectroscopy(XPS) and transmission electron microscopy(TEM) were used to analyze the morphology, structure and chemical composition of the oxide films formed on stainless steel(SS) 316L in the simulated pressurized water reactor (PWR) primary water at 325℃. The results showed that the oxide film formed on 316L SS in high-temperature and high-pressure solution without dissolved hydrogen had a double layer structure composed of iron-rich outer layer and chromium-rich inner layer. With increasing dissolved hydrogen, the outer big oxide particles became small and more compact, but all the oxide films were consisted of spinel oxide. XPS results indicated that, with increasing dissolved hydrogen, the thickness of the oxide film increased. In addition, the nickel content in the oxide film increased, whereas the chromium content decreased.

Based on metal polarization theory, the influence of external electric field voltage on the passive film of reinforcement was studied through experimental analysis. By defining the reasonable value of the voltage applied by electric field, discrimination method of steel depassivition under continuous de-energized condition was proposed. An rapid test to determine chloride threshold under field conditions was designed, for comparison, a normal test to determine chloride threshold by the natural chloride penetration was also carried out correspondingly. The results showed that chloride threshold determined by rapid test was slightly smaller than the value determined by the natural penetration test, the ratio was about 1.261, which verified the feasibility of this test method.

Ultra high toughness cementitious composites (UHTCC), featured with its strain hardening characteristic and outstanding crack controlling under tensile conditions, could greatly enhance the durability of reinforced concrete structures and prolong the service life of infrastructures. By means of accelerated corrosion test and direct pulling test, bond properties between corroded rebar with different corrosion ratio(0, 1%, 2%, 3% and 5%) and UHTCC were investigated, did the same for corroded rebar and ordinary concrete while other things being equal. The relationships between average bond stress and end slip with different corrosion ratio were presented. A constitutive model for bond slip relation between rebar and UHTCC was applied for simulating the test results, and fit well. The relationship between maximum average bond stress and corrosion ratio indicated that UHTCC could restrict the corrosion expansion. The maximum average bond stress of rebar and UHTCC increased linearly before corrosion ratio up to 3%, then remained constant till to 5%, while the maximum average bond stress between rebar and concrete decreased rapidly when the corrosion ratio exceeded 2%.

The localized corrosion behavior of 304 stainless steel immersed in 0.5 mol/L FeCl₃ solution was investigated for a long-term monitoring as long as 350 h by electrochemical noise (EN) technique. The EN data was analyzed mainly by spectrum analysis, time-domain statistical analysis and wavelet transform. The whole process can be divided into four parts, which can be differentiated clearly according to the characteristic EN transient peaks. The variations of current standard deviation, R_n and PI during the whole monitoring period all give the coincident result. The 3D energy distribution plots(EDP) give the energy contribution of each detail crystals during the whole monitoring time. The figure which only concerns contribution of detail crystals shows that, the energy accumulation in band d4~d6 increases with the metastable pits occurrence. And as this process stepped into stable pitting stage, a max of the energy contribution occurs during the band d5~d8.

The protective performance of cathodic protection (CP) system consisted of Zn-Bi sacrificial anode and Ni-Cr-Mo-V steel was investigated by electrochemical measurements and morphology observation. The shallow-deep water alternating cycle was simulated by immersed the CP system to cyclic conditions of 16 h immersion at atmospheric pressure and 8 h pressurized at 3.5 MPa. The experiment results indicated that the cyclic hydrostatic pressure had significant influence on the CP system. Comparing with the counterpart at atmospheric pressure, the anode potential instantaneously responded to the cyclic hydrostatic pressure and the discharge performance of anode decreased due to the deposition of corrosion product. At the cyclic hydrostatic pressure, the CP system exhibited the higher slope parameter, which indicated that the CP system can not provide the adequate protection for Ni-Cr-Mo-V steel.

An analog device of the marine environment corrosion in laboratory conditions was established. This device can simulate a variety of marine corrosion environments, such as wave splash zone, tidal zone and sea water immersion zone, etc. A new type of electrochemical sensor for the waves splash zone corrosion was developed. Electrochemical noise characteristics of simulated corrosion test rack in different parts of the surface were obtained by using this sensor and noise resistance R_n of different parts were compared and analyzed. The results showed that the anticorrosion performance of part B was better than part A.

The nanocrystalline zinc coating which the grain size was within 60 nm was obtained when a combinatorial additive was added to alkaline non-cyanide bath. Besides, the role of two components of combinatorial additive was analyzed through comparing the differences with deposition potential、morphology and grain size of zinc coatings which were obtained in the bath contained additives or not. The results showed that the additive A played a role of grain refinement, the additive B played a role of leveling, and a strong synergistic effect was existed when both A and B was used.

The degradation process of polyamide epoxy varnish for aluminum alloy was studied in ultraviolet/ salt spray combined environmental test, the morphology of the coating was observed by environmental scanning electron microscopy(ESEM), other physical parameters such as volume resistance, surface resistance were also measured in the exposure test. Meanwhile, EIS(electrochemical impedance spectroscopy) was utilized to monitor degradation process of the coating. The results showed that the porosity of the coating increased and the volume resistance and surface resistance decreased in the degradation process. EIS illustrated different stages of the degradation process. First order type degradation kinetics or simplified KWW model are suggested and discussed based on the quantitative measurements; coating failure criterion determined from EIS was also suggested. It is considered that the electrical resistance and electrochemical impedance modulus at low frequency is suitable to construct degradation kinetics.

To obtain high strength and good corrosion resistance of Mg-9Gd-4Y-1Nd-0.6Zr alloy, effects of Ce on microstructure and corrosion resistance of Mg-9Gd-4Y-1Nd-0.6Zr magnesium alloy was investigated by means of scanning electron microscopy, X-ray diffraction, corrosion mass loss test, electrochemical impedance spectroscopy and potentio-dynamic polarization test. The Mg alloy with 5% Ce shows better corrosion resistance. Its corrosion current density decreased about 55.6%. Its corrosion potential moved positive about 141 mV than that of Mg-9Gd-4Y-1Nd-0.6Zr alloy. Rare earth elements in the Mg alloy enriched along grain boundary as network distribution were caused by proper content of Ce. Corrosion resistance of the Mg alloy was enhanced by change of second phase particles. Their volume fraction in the Mg alloy surface increased higher and their sizes decreased than those of Mg-9Gd-4Y-1Nd-0.6Zr alloy.

The effect of 6-nitrobenzimidazole on the zinc corrosion in 0.1 mol/L KOH solution has been studied by electrochemical, weight loss measurements and quantum chemical calculations. It has been shown that 6-nitrobenzimidazole act as an anodic inhibitor, can effectively restrain the process of the anodic oxidation of zinc. The highest value of inhibition efficiency is 96.8% at 5 mmol/L concentration. Thermodynamic calculation suggests that the adsorption of 6-nitrobenzimidazole follows Langmuir adsorption isotherm.