In this present paper,the operation technology for preparation of aluminium-chromium alloy coating by electron beam evaporation pla ting was studied.Corrosion resistance of the coatings was investigated,meanwhile the phase,morphology and the effect of heat treatment on the diffusion between the Al-Cr coating and the matrix were discussed.The analysis of ingredients of t he coating and the target shows that the chromium contents of the coating are ve ry different from that of the target.It is proved that Al-Cr alloy coating of th e chromium contents of 1.5%～5% can be regarded as the anodic coatings for norma l steel matrix,which accordingly has good electrochemical protection function i n 283K,30 g/L NaCl solution.The major phases of the coating are Al and a small q uality of Cr9Al17.Cr9Al17 in the coating increases with the Cr c ontent of the target.The deposited coating takes on the orientation.After 600℃, 1 h heat treatment,ingredients of the coating and matrix diffuse each other.

The corrosion behavior of pure nickel with solid Na Cl deposit in dry air or in wet oxygen at 600℃-700℃ was studied.The results in di cated that corrosion was more severe at 700℃than that at 600℃.Furthermore,the mass gain of the specimen with solid NaCl deposit in dry air at 700℃ was very o bvious.But the mass loss of the specimen with solid NaCl deposit in wet oxygen a t 700℃ was obvious.The corroded samples were examined by scanning electron micr oscopy (SEM) with energy dispersive X-ray (EDX) and X-ray diffraction (XRD).The relevant corrosion mechanism was also discussed.

The surface films formed on modified alloy 800(all oy 800M)polarized potentiostatically at different potentials in boiling 50%NaOH +0.3%SiO2+0.3%Na2S2O3 solution for two hours were analyzed by means of A uger electron spectroscopy(AES).At the potentials between -500 mV and 80 mV ,the enrichment factor of Ni was an order of magnitude higher than that of Fe and Cr in the surface films.General intergranular attack(IGA)at -500 mV occurred due to S enrichment and Cr depletion in the surface films.The curves of enrichment factor vs.potential had a critical potential(Ecr=-40 mV)where the al loy suffered from IGA due to the dissolution of active grain boundaries when str ess ruptured the surface film whose protective ability decreased by the transfor mation of Ni(OH)2 into a new unstable oxide of xNi2+yNi3+O y(OH)2x+y.At E=-30 mV～40 mV,intergranular stress corrosion cracking (IGSCC)was attributed to the formation of xNi2+yNi3+Oy·(O H) 2x+y and the percentage of active grain boundaries over a critical percentag e.

The behavior of N80# steel in acid solution at va rious pH values and with various CH2SO3 was studied by means of stable polarization,anodic linear potential sweep and a.c.impedance.The result showed that the addition of H2SO3 could increase the corrosion rate of N80# steel for two reasons;one is the decrease of solution's pH value,the other is the pro duction of an new mid adsorptive matter.The adsorption intermediate product was F e(OH)ad in process of the corrosion reaction of N80# steel in HAc-NaAc wit hout H2SO3.When H2SO3 was added to the acid solution,the adsorptive inte rmediate product was Fe(HSO3)ad.

The cavitation erosion (CE) behavior of CrMnN ferri te-austenite duplex stainless steel in distilled water and 3%NaCl solution has b een investigated by using a magnetostrictive-induced cavitation facility.The fre e-corrosion potential and polarization curve under quiescent and cavitating cond ition have been measured by electrochemical technique.The micrographs of damaged surfaces were observed by scanning electron microscope (SEM).It was found that the cavitation resistance of CrMnN steel was higher than that of CrNiMo steel.T he failure mode of ferrite phase was brittle fracture，which had adverse effect on the resistance to CE，while the austenite phase failure was a ductile failure in CrMnN steel.The excellent resistance to CE was related to the good mechanica l properties of austenite phase and the consumption of cavitation energy by plas tic deformation involving slip and twinning.The cavitation shifted the free-corr osion potential in the active direction about 300 mV and increased the current d ensity which maintained the passivity of stainless steel in order of 3，the comp onent of total weight loss directly and indirectly caused by chloride sodium was 5.7%.

The potentiodynamic polarization method has been us ed to investigate the electrochemical behavior of 1Cr17 stainless steels in NaCl -UO2(NO3)2 solution.The hydrogen gas was evolved in the cathodic reaction region,and led to the evolution of uranyl ion hydrolysis.The film formed on t he stainless steel electrode under the potentiodynamic polarization with increas ing sweep potential.SEM observation revealed image from the surface of the speci men.The deposit film was measured by Ar ion gun sputter,and the thickness was ab out 40 nm.The XPS analysis indicated that the surface region of film formed on the stainless steel electrode is composed of U(Ⅵ).The forming mechanism of depo sit film was initially discussed.

A suitable mixture without chromium is developed for protection of mag nesium alloys by treatment with the anodic oxidation.The aqueous solution is co mposed of NaOH、Na2SiF6 and an organic additive.The potentiodynamic polariza tio n measurement showed that the film had outstanding protective ability in 3.5% Na Cl solution.The morphology and component of the anodic oxidation film have been analysed by SEM,XRD,XPS and EPMA respectively.XRD and EPMA analysis revealed that the film was made of MgO、MgAl2O4 and 2Al2O3·2SiO2·H2O.Si and Al oxides make up the volume shrinkage of magnesium oxides,so that the film has no crack which provides a good condition against pitting.And the even dispersio ns of Si and Al in the film is another factor that the film has better protectio n.

Based on the test results by using rotating simulat ion apparatus,erosion-corrosion of duplex stainless steel in flowing 3.5%NaCl so lution is studied numerically.A comprehensive mathematics model for flow induced corrosion includes three components:the flow model,mass transfer model and corr osion model,which was established by combination of numerical method with experi mental measurement.It was studied that hydrodynamic parameters can affect the co rrosion process.The results show that corrosion is controlled by self-passivatio n process of anode and the mass transfer process in the film of duplex stainless steel is the slowest one in the processes of corrosion.The corrosion rate obtai ned from numerical method is almost equal to the measured one,and the corrosion mechanism of duplex stainless steel was further verified by numerical simulation 

The inhibition behavior of polyhydric alcohol phosp hate ester (PAPE) corrosion inhibitor to steel surface have been studied by pot e ntiodynamic in natural seawater.The results indicated that the inhibition film l ayer was formed stably on the steel surface.The inhibitor is a negative catalyti c and cathodic inhibitor and it owns good inhibition efficiency at the content o f 300ppm.The surface morphology and composition profile of the inhibitor film we re also investigated by Auger electron spectrometry (AES)、atomic force microsco pe (AFM).The results show that the thickness of the inhibitor film increased wit h the time extent,and the chemical composition of the film includes P,Fe,O,C,Ca, Mg.So the major structures of the film are the complex compounds which constitut ed by poly-phosphate and Ca2+,Mg2+,Fe2+ et al ion.

Effect of three kinds of ion bombardments,including deposited with d.c.bias voltages,circulated-argon ion bombardment,and at in tervals on microstructures and corrosion resistance of aluminum coatings on uranium substrate was investigated.The results show that coating microstructu res are influenced strongly by ion bombardment methods,of which coating microstr uctures correspond to their different corrosion resistance to uranium. The microstructures are much more closely packed and the corrosion resistance ar e much better at -100 V,-200 V and -500 V than those of at -300 V,0 V .The microstructures and corrosion resistance of aluminum coatings ca n also be improved remarkably by both circulated-argon ion bombardment and at in tervals deposition.All of aluminum coatings can provide protection for uranium t o different extent.

The adsorption and the inhibiting effect of polyami nes in naphthenic acid/A3 steel system are studied through weight-loss and elect rochemical method.The results show that polyamine has the capability to inhibit the corrosion of naphthenic acid.The coverage lowers down as temperature rise.Th e adsorption heat ΔH=-51 kJ/mol<0.According to that,the contribution of polyami nes turning naphthenic acid into non-corrosion substances is proposed.

Microstructure,phase constitution,hardness and corr osion wear test of the different corrosion media of Fe-base self-fluxing alloy layers (HFe55 and DFe55) and Ni-base layers(HNi60 and DNi60) by oxy-acetylene f lame and plasma arc had been studied on the 16Mn steel substrate.Results show th at the microstructure of the layers all have characteristic of dendrites,and the layers are consisted of γ dendritic solid solution and fine eutectic structure between the dendrites.The dendrite of Fe-base layers is flourishing,but Ni-bas e layer is finer.The higher the hardness of the layers,the better the corrosion wear resistance of the layers.The order of the hardness and wear resistance from high to low is HNi60,DFe55,DNi60 and HFe55.The corrosion wear resistance of the layers in 4%HCl (pH6) and 4%NaOH (pH8) liquid media is lower than that in water,especially in 4%HCl acid media.

The microstructure,crack shape,appearance of the fr acture and the composition of the corrosion product were studied with the help o f optical microscope,scanning electron microscope (SEM)and electron spectromete r.Investigations confirmed that the boiler tube failed from both the superfluous free hydroxyl in boiler water to determine which a new method has been devised and the local overheat caused by deposition in boiler tubes.The relationship bet ween conductivity and free sodium hydroxide at simple makeup demineralizer efflu ent was proposed.It was found that the poor quality of makeup water was the root cause of superfluous free hydroxyl in boiler water.The long-term prevention of crater corrosion will include:keeping a clean boiler,controlling boiler free hyd roxyl levels,avoid flame impingement or burner misalignment,and eliminating weld protrusions and other features that can disrupt the local boiler water flow.It is also extremely important that the makeup water treatment is optimized,and con ductivity controlled to a specified limit.

Current research status of pitting corrosion,interg ranular corrosion,stress-corrosion cracking(SCC) and exfoliation corrosion of Al -Li alloys are reviewed in this paper.The effect of processing,heat treatment,mi crostructure and corrosion medium on the pitting and intergranular corrosion beh avior and SCC susceptibility of some Al-Li alloys are given,the correlated effec t mechanisms are described and some new test methods for Al-Li alloy exfoliation are reported.Meanwhile,the next research objective is outlined.