Effect of cathodic protection on the cavitation corrosion behavior of Q235 Steel in 3.5% NaCl solution was studied by mean of mass loss method, EIS and SEM. The result showed that nearby the cathodic protection potential of -800mV, the corrosion rate reduced dramatically. In addition，there was a trend that hydrogen embrittlement phenomenon could occur by the hydrogen evolution potential of about -1200 mV. At the same time, the EIS under cavitation corrosion condition at different cathodic protection potential were fitted by software ZsimpWin and the change characteristics of the R_t value with time was revealed. The R_t value would decrease with time by the open circuit potential but would have an increasing trend at -800 mV while it indicated a decline trend with time by the potential -1000 and -1200 mV. Furthermore, it is also noticed that the R_t value was fairly small when the applied potential was -1200 mV.

The conductive polyaniline(PANI) film was synthesized by cyclic voltammetry（CV） on 304 stainless steel. The effect of electropolymerization parameters (applied potential, scan rate, cycle number and concentration) on corrosion resistance of PANI was systematically studied by polarization curves. The results show that synthetic conditions affect significantly the corrosion resistance of PANI. The best protection performance can be obtained when PANI was synthesized on SS by CV between 0.2 and 0.9 V (SCE) with a scan rate of 10 mV/ s for 3 cycles from 0.3 mol/L sulfuric acid solution containing 0.1 mol/L aniline. PANI has better protective properties in 0.5 mol/L H₂SO₄ than that in 3.5%sodium chloride solutions. The morphology of conductive PANI was observed by scanning electron microscopy, PANI is granular and fibrous structures.

The effect of immersion time on corrosion behavior of microarc-oxidized AZ31 Mg alloy in a simulated body fluid was studied. The microarc oxidation was performed in an electrolyte of 30 g/L sodium phosphate (Na₃PO₄) at a voltage of 250 V and a pulse frequence of 3000 Hz for, , 5 min. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to characterize the corrosion behavior. The corrosion current density increases during the first 14 days and then decreases in the subsequent days. The electrochemical impedance is in accord with the result of the corrosion current density. The characterization of corrosion products revealed that hydroxyapatite (HA) was formed on the surface of the samples. The ratio Ca/P of the corrosion products was determined by the X-ray fluorescence (XRF) technique, and the value is around 1.67. The corrosion resistance of the microarc oxidized samples is enhanced due to the formation of a corrosion product after immersion in simulated body fluid for more than 14 days. The corrosion inhibition mechanism of the corrosion process is discussed and presented with a physical model.

The main environmental factors of soil corrosion for carbon steels in regional soils of 14 test cities in China were determined using fuzzy clustering. By analyzing the physical and chemical properties of soil and annual corrosion data of carbon steel, the soil corrosion prediction model for carbon steel was built. The reasonableness of the corrosion model was verified by using the BP artificial neural network to learn, train, simulate, and compare with the corrosion test results of the carbon steel samples buried in 14 cities regional soil. The results show that water content, pH, Cl^- content, SO₄^2- content, soil conductivity and total dissolved salts are the six main factors on soil corrosion of carbon steel in the 14 cities regional soil, and a stable forecasting model can be built based on the BP artificial neural network, which well predicted the corrosion rates of carbon steel in regional soils of 14 test sities.

Corrosion behavior and failure mechanism of hot-dip galvanized steel (HDG) were investigated in an indoor simulated acid rain environment. The surfacial and cross-sectional morphologies of corroded HDG were observed by SEM; the elemental composition of the corrosion product was analyzed by EDX; the phase constituent of corrosion products was characterized by XRD; the corrosion rates of HDG were tested by mass-loss method. The results showed that the corrosion rate firstly decreases sharply, and declines slowly, and then rises slightly with time; corrosive media locally attack the galvanized layer generating pitts and corrosion products (ZnO ZnCl₂ xH₂O)， then the later accumulated on the HDG surface. It follows that the corrosion products may act as a barrier， soon after it totally covers the surface of the HDG plate， to inhibit the penetration of corrosive media in the simulated acid environment. Initially corrosion rate decreases rapidly because the corrosion reactions proceed and corrosion products occur. The corrosion products become so dense that the corrosion rate further slows. Finally corrosive media penetrates galvanized layer，and corrodes the substrate， the corrosion rate becomes larger slightly. Throughout the process， the HDG layer provides certain protection to itself and the substrate

Several lower carbon spring steels of different composition were designed. The corrosion resistance of the steels was evaluated by means of salt-spray test polarization curve measurement, whilst the morphologies and composition of the corrosion products were characterized by scanning electron microscope (SEM) with energy disperse spectroscopy (EDS), and X-Ray Diffraction (XRD). The results show that trace rare earth can enhance the corrosion resistance of spring steels in NaCl aqueous solution, and the corrosion potential was shifted positively, and the corrosion current density was reduced. Corrosion products of spring steels in 5% (mass fraction) NaCl aqueous solution mainly were β-FeOOH. The scale on the spring steels with rare earth exhibits good adhasive to the substrate and denser than that without rare earth, which could interfere the contact between corrosion medium and matrix and therefore could reduce the corrosion rate.

The corrosion behavior especially pitting resistance of TTS443 stainless steel, in comparison with 304 stainless steel, was studied by means of polarization curves and electrochemical impedance spectroscopy (EIS), in NaCl and HCl solutions respectively. The results showed that, with the increase of mass fraction of Cl^-, the pitting potential (E_b) of TTS443 stainless steel decrease first and then increase ,and corrosion current (I_corr) increase first and then decrease, in 12%NaCl solution, while the corrosion rate was the highest. In solutions with the same concentrati on of Cl^- the corrosion rate of TTS443 stainless steel was slower than 304, but the pitting corrosion resistance is weaker. However in HCl solution, with the increase of concentration of HCl, the corrosion rate was increased, the value of E_b reduced. In solutions with the same acidity, the corrosion rate of TTS443 stainless steel was faster, and the pitting corrosion resistance was weaker rather than 304 stainless steel.

Abstact: An uniform Ni-P-nano-Al₂O₃ coating was eletroless plated on 45 carbon steel, and the coating was then treated by high power CO₂ laser beam with output power varying from 200 to 800 W. The surface morphology and the phase constituents of the coatings were observed and characterized by Scanning electron microscope (SEM) And X-ray diffraction (XRD) respectively. The micro-hardness and abrasion property and electrochemical corrosion behavior in 3.5%NaCl solution of the coatings were also examined.. The results reveal that with the laser power increasing the surface roughness of the coating decreases at first and then increases, and the quantity of nano-Al₂O₃ on the coating surface decreases gradually. The as-plated Ni-P-nano-Al₂O₃ coating is of amorphous structure. The phase transformation occurs from amorphous to crystalline after laser modification, the later consisted of crystallized phases of Ni and Ni₃P. The micro-hardness and wear resistance of the coating increases at first and then decreases with the increasing laser power. The corrosion potential of the laser treated coating shifts to a more negative value as the laser power increases, which implies a decrease of the corrosion resistance. The coating exhibits the best comprehensive property after the modification treatment with laser beam with power 400 W.

The corrosion behavior of Zr-2.5Nb alloy specimens with and without ZrO₂ coating was investigated in supercritical water (SCW) at 500 ℃ by 25 MPa. SEM, EDS and XRD were used to characterize the morphology, element distribution and crystal structure of the oxide scales. The Zr-2.5Nb alloy exhibited large mass gain after exposure to SCW. The surface oxide on specimens without coating is mostly tetragonal phase at the beginning of exposure, and then gradually transformed to monoclinic phase with the increasing time. Cracks can be observed on the oxide scales on non-coated specimens, while exfoliation can be found on ZrO₂ coated specimens. It is considered that the tetragonal phase in oxide scale is beneficial, while the monoclinic phase is detrimental to the corrosion resistance of zirconium alloy.

The effect of LSP on electrochemical corrosion behavior of 2A02 aluminum alloy in 3.5%NaCl solution was studied by using electrochemical techniques and transmission electron microscopy. The experimental results showed that large number of dislocations was produced in the alloy after the LSP and then the dislocations piled-up with the increasing number of LSP, which induced the original grains to be subdivided into different subgrains, so the grains are refined. The residual stress on the Al-ally surface increased with the increasing number LSP. Whilst the free-corrosion potential and pitting potential of 2A02 aluminum alloy shifted positively in 3.5%NaCl solution with the number of LSP.

The influence of cationic surfactant polyquaternium on alkaline degreasing process of the printed circuit board (PCB) was evaluated by means of the examinations of the backlight degree, SEM and EDS after that the degreased PCB was Cu-deposited. The results show that polyquaternium has a significant influence on the alkaline degreasing process. Glass fiber could be observed on the surface of the Cu-deposited PCB hole after alkaline degreasing in polyquaternium-free bath, and the backlight level was only 6th grade due to the serious light leak. The electroless deposition rate and the backlight degree of the Cu-deposited PCB first increased and then decreased with the increase of polyquaternium concentration in alkaline degreasing bath. When the dosage reaches 13.5 mL/L, glass fiber is rare to be seen on the hole wall, and the backlight level reaches the highest of 10th grade. The polyquaternium not only adjusts the electric charge on substrate, which promotes the adsorption of active colloid palladium particles, but also reduces the interfacial tension and enhance the wettability of alkali solution to the surface of PCB hole. Besides, polyquaternium is the main source of OH^-, and as a result the oil is removal from PCB hole-wall.

The corrosion resistant steel of D36-RCW was developed which can be used at upper deck plate and inner bottom plate for cargo oil tanks of crude oil tankers. This steel has been tested according to the “Test procedures for qualification for corrosion resistance steel for cargo tank in iol tankers ” issued by the China classification society (CCS) , the experimental results show that the mechanical properties and welding performance and corrosion resistant properties of the steel all meet the requirements of CCS, the general corrosion rate of this steel plate was 0.3 mm/a in the corrosion environment corresponding to the inner bottom plate, the predicted corrosion rate for 25 a was less than 2 mm in the corrosion environment corresponding to the upper deck plate.

Corrosion failure of water pipelines was analyzed by means of corrosion morphology observation, corrosion product analysis by using SEM, XRD and EDS technologies, as well as analysis of physical and chemical properties of underground water and coal ash and the property of microbe nearby the pipelines. The results showed that the corrosion failure of water pipelines was due to the effect of oxygen concentration difference cell formed as the pipelines suronded by water containing coal ash and silty clay. However, the pipelines were not affected by stray current corrosion and microbiological influenced corrosion. Meanwhile, the entire lose effective of the coating for pipelines resulted form the strong corrosiveness of underground water was the important factor responsible to the rapid corrosion failure of pipelines.