Corrosion results of 12 types of copper alloys exposed to marine splash zone at Qingdao Sea area of China were reported. Corrosion behavior and law of copper alloys in splash zone was summarized. Corrosion rate of copper alloys in splash zone was low. Corrosion type of copper alloys was uniform corrosion in splash zone for short period exposure.Exposing to splash zone for long period,copper alloys occurred not serious pitting and crevice corrosion.Their maximum pitting depths in splash zone at Qingdao Sea area for 16 years were less than 0.3mm.Brass had tendency of dezincification corrosion; and Cu-Ni alloys took place denickel corrosion.Corrosion rate of pure copper and bronzes fell with exposure time.Corrosion rate of HMn58-2 and HSn62-1exposed to splash zone during 1~4years fell with exposure time,after which the corrosion rate raised with exposure time.Corrosion rate of HAl77-2 and BFe10-1-1rose slowly with exposure time.Exposing to splash zone for long time, xorrosion resistance of copper alloys in splash zone was better than that in full immersion zone and tide zone, and was poorer than that in marine atmosphere.

This srticle, through measurement of diffusive reflectivity,X-ray photoelectron energy spectra and mass spectra,studies the contamination of magnesium fluoride(MgF2)coating diffusive reflection flakes by solid and gaseous nitrogen tetraoxide(N2O4).Our experiments show tha solid N2O4 may erode seriously the MgF2xoatings.The diffusive reflectivity of the coating surfaces,after contaminated by solid particles of N2O4,will decrease about 20%~30%.Within a certain period of time, the effects of gaseous N2O4 on MgF2coatings obviously depend upon its pressure.Exposure in N2O4 vapor for ten minutes,at the pressures of 6.9×104Pa and 200Pa,the 40μm coatings are almost disappeared for the former case,amd accompanied by about 20%decrese of the surface diffusive reflectivity,for the latter case there are a little changes in the atomic cinstitution and diffusive reflectivity of the coating surface.This article also provides the mole densit for absorption of N2O4 molecules on Mgf2 coating surfaces, and the probability for N2O4 molecules in collision with the surfaces to extract Ngf2 through a chemical absorption process.

Taking epoxy coal tar as material of coating,the influene of hunk of coating defect on corrosive characteristic of carbon steels and effectiveness of cathodic protection has been investigated.EIS of Q235 steel in 3.5% NaCl water solution with hunk of coating defect was determined.Experiments have shown that,on free corrosion potential,the corrosion of carbon steels with disbonding defect of coating os heavier than that of breaking defect of coating with times.On cathodic polarization poteneial,the effectiveness of cathodic protection of carbon steels with disbonding defect of coating gradually weaens with times and loses eventually.The effection of cathodic protection of carbon steels with breaking defect of coating is better than that of carbon steels with disbonding defect of coating.Penetration of electrolyte solution into coating and the creice corrosion between coating defect and surface of steel matrix is main reason of corrosion on carbon steels with hunk of coating defects.

The corrosion behavior and the effect of the corrosion inhibitor on those behavor of carbon steel in MEA solution abounded with H2S was investigated by static weight loss test, electrochemical method and surface analytical techniques.The inhibitive mechanisms of IMC-C5 inhibitor under the circumstance were discussed.The results show that mild steel was severely damaged in MEA solution abounded with H2S and IMC-C5 inhibitor has an excellent inhibitive performance mainl from the strong retardation to the anodic process.The corrosion inhibitor is an anodic adsorption type inhibitor.

The inspection of the biofilm attachment on metal surface in seawater was studied by electrochemical technique. in natrral seawater,the open - circuit potential of stainless steel was ennobled due to the biofilm formation on the metal surface,and has a linear relationship with the number of bacteria attached on metal surface.Taking into account the corrosion potential of copper was kept constant in seawater,a compound electrode was made with stainless steel and copper,and after demarcation it can be used to assess the attaching ability of microbes in different seawater media according to the change of the potential difference between the two metals.

The corrosion of rebar in concrete was studied by 8×8 liner wire - beam electrode.The corrosion potential,polarization resistance and corrosion rates distributions of wire - beam electrode in the same or different depth were obtained by estimated corrosion potential and polarization resistance in 10% NaCl solution.The effect of chlorine ion concentration and the structure of concrete on them were studied.The results showed that the xorrosion of iron wires in concrete were nin-uniform.The corrosion potential and polarization resistance were scattered.With the increase of immersion time.the corrosion potential shifted negatively,the polarization resistance reduced and the difference of corosion potential became larger.With increasing the embedded depth of iron wire,the negative shift value of corrosion potential,chlorine ion concentration and corrosion rates reduced,but polrization resistance increased.

Influences of temperature on CO2 corrosion behaviors of P110 steel were studied in stimulated oilfield environments. Morphologies of scales and their effects on corrosion rate and corrosion shape were analyzed by SEM and XRD. The results showed, at 40℃, corrosion products were similar to loosen soil, few and hanging on the surface of the material composed by deposited KCl. In 90℃, corrosion products were grains, compact and much holes in it, constituted by calcium/magnesium/iron carbonate and few KCl and Fe2O3. In 140℃, corrosion products were in the similar morphology as compact clay in the outer layer and grains in the inner layer, made up of FeCO3 and KCl. The phenomena of different morphology in different temperature resulted in that the maximal corrosion rate presented in 90℃.

SEM and salt spray test were employed to characterize the surface morphology and corrosion resistance of ceramic coatings formed by micro-arc oxidation on magnesium alloy. The results show that the coating grows in the following steps, i.e., the stage of anodic deposition, micro-arc oxidation and local arc light. In the first stage of anodic deposition, the flocculent oxidation film deposits and extends on the surface of MB8 magnesium alloy. The next stage of micro-arc involves the decreasing and vanishing of flaw in the coatings, and the ceramic film formed is relatively uniform and dense, with very small micro-pores. However, in the last stage of local arc light, the relative large holes appear on the surface of the coatings, therefore, the ceramic film becomes looser. With increasing treated time, the corrosion resistance of the coatings increases, and is best at the treated time of 8～12 minute before it deteriorates.By controling the energy allocation of the different time and extending the time of uniform growth, the uniform and compaction ceramic coatings can be obtained.

The oxidation behavior of pure copper and Cu-Ti alloy layer made by double glow discharge process were investigated in air at 400℃~700℃.The formed oxide scales were examined by XRD,and the oxidation mechanism was discussed.The results indicated that the oxidation resistance of Cu is significantly improved by titanizing treatment.After oxidation at 700℃ for 100h,the formed oxide scale on pure copper consists of Cu2O,CuO and that on titanized Cu is mainly composed of TiO2.The oxidation kinetic curves follow parabolic rate law.

The Electrochemical impedance spectroscopy (EIS) of the simulated specimens with different coatings was studied. The slope of log impedance modulus |Z| versus log f was put forward as characteristic parameter k（f）. The deterioration process was divided into five sub processes by using Kohonen neural networks. The input of the networks is k（f）of different samples at different immersed time. The coating state can be defined by the output of the networks. Therefore the output can be considered as the quality index of the coating to some extent. The result indicates that the degradation process varies with different coatings and preparation techniques. The network proves to be useful to evaluate the coating performance.

The effect of rare earth elements Ce and Nd on the oxidation resistance of NiAl-28Cr-5.5Mo-0.5Hf alloy has been studied in the paper.The microstructure and composition of oxide layer have been studied by means of X-ray diffractometer and scanning electron microscope with an EDAX unit. The results show that the addition of rare earth elements changes the content of the constituent scales in the surface scale, eliminates internal oxidation and reduces mass gain of the oxide.

Current coating detection technology and evaluation index are summarized. A method of fast monitoring coating is studied according to the existing coating detection technology, and the relevant mathematical model and evaluation method is discussed. In practice, one can evaluate coating using data of cathode protection system directly or using data from test by himself. The application to one pipeline in Sichuan indicated that the method is fast and valid, which can make the sequential tracking and dynamic monitoring of coating status come true, and the method can locate the coating defects quickly and decrease the maintenance cost of pipeline.

Several prediction models for CO2 corrosion of oil and gas fields have been reviewed. These models are mainly divided into three categories: empirical models, semi-empirical models and mechanistic models. Empirical models are based on laboratory or field data. They are simple and coincide with much of field data quite well. Semi-empirical models are developed according to chemical, electrochemical reactions kinetics and diffusion of species to and from the bulk phase. Then deviation from prediction models will be corrected by multiplying with factors. Mechanistic models are based on CO2 corrosion mechanism combining corrosion thermodynamics and kinetics with diffusion kinetics. Because there are many factors affecting CO2 corrosion and the CO2 corrosion mechanism is extremely complicated, it is quite difficult to develop an accurate universal prediction models. The present prediction models, including empirical models, semi-empirical models and mechanical models, are imperfect and need further improvement.

This paper summarizes systematically the recent progresses in corrosion influences and rate prediction of sweet corrosion affected by crude oils, introducing the methods of studying corrosion process of sweet corrosion, and bringing forward the issues that may be paid special attention to while studying the influence of crude oils. However, crude oils usually demonstrate some inhibition in specific conditions. Corrosion product film and oil wetting are two great differences in existent rate prediction model in sweet corrosion. However, the approaches and manners to dispose crude oils will affect the prediction results no doubt. It is remarkably beneficial to study and develop an appropriate prediction model if the properties and laws toward sweet corrosion of crude oils are been studied thoroughly. And there is a realistic meaning in saving investment and operational costs while utilizing the possible inhibition of crude oils.