The dissolution behavior of FeNiSiB amorphous alloy has been studied by STM in situ.The dissolution process of the amorphous alloy can be divided into two periods:surface dissolution and matrix dissolution.The surface dissolution behavior is dependent on the manufacture process while the sturcture characteristics play an important role in the dissolution process of matrix.General corrosion occurs on the amorphous alloy even in nanoscale.The general corrosion process of amorphous alloy has been detected again in microscale by STM in situ.The smallest unit that takes part in the corrosion is Bernal polyhedron.General corrosion can be described as that any part of the surface will be anodic region or cathodic region in defferent corrosion period.The harmonious development of this process led to the general corrosion mode in macroscale.

The average growth stresses in Al2O3 scales formed on Fe-23Cr-5Al alloy during oxidation at 1000℃,in air have been measured by using a new deflection technique.The relaxation of oxide stress has also been studied.The average growth stresses in Al2O3 scales decreased with thickening of the scales,their values were over the range of -1000～-100MPa.The stresses in the substrate alloy were much lower,in the order of 1MPa.Both the substrate alloy and alumina scales might creep at 1000℃.During the annealing of the oxidized specimen,the rate of the stress decrease with time was 6.9～18.4times higher for the scale of 0.039μm than that for the scale of 0.30μm.

High temperature oxidation behavior of aluminide coatings obtained by low pressure gas phase deposition under 0～0.014MPa at 1080℃ for 4 hours on Co-base superalloy DZ40M has been primarily investigated.The results indicated that isothermal oxidation process of the coatings in air at 900～1100℃ showed three stages,including the initial,the stable and the accelerative.During the initial stage the coating oxidation controlled by interface reaction developed rapidly.The stable stage was controlled by diffusion within oxide film and proceeded very slowly.Because the degeneration of the coatings obsturcted the formation of the protective oxide scale,the samples were oxidized stronhly during the accelerative stage.The addition of Ti during deposition and increase in temperature accelerated the oxidation and degeneration of the coating, and transfered the stable oxidation stage into the accelerative.Due to the formation of θ-Al2O3 the oxidation weight gains of the coatings at lower temperature were more than that at higher temperature,thus decreased in the order:at 900℃,1000℃ and 1050℃.At 1050℃,only α-Al2O3 appeared.

Solvent extraction method has been set up to evaluate the degree of cure(DOC)of a new type of fusion-bonded epoxy(FBE)coating obtained under different curing conditons.The specimens were extracted in hot 2-butanone.The results showed that the DOC increased with the increase in curd temperature and curd time from 160 to 230℃.Heat decompositon was observed for the coating cured at 230℃.horizontal shifts of the DOC vs In(time)curves at defferent cure temperatures resulted in a master curve.The kinetically controlled reaction yielded a single Arrhenius activation energy (91.4kJ/mol).It implied that there was only one overall reaction mechanism in the temperature range under stuey.The surface morphology observation of the extracted samples was carried out under SEM,which verified the feasibility of solvent extraction method.

Charge curve analysis technique(CCAT)has obvious merits for study of the systems with long time constant,such as passivated metals.But conventional CCAT is limited to apply in mini-polarization range and gets linear polarization resistance only.A charge curve equation without linear simplificaton for passivation/corrosion systems is derived and it is proved that the reciprocal of defferential of charge curve is linear with expontial function of time. Based on the galvanostatically measured charge curve data at equal time intervals,numerical defferentials aat sampling times are calculated and two linear regression operations are made.Then electrochemical parameters of the system (corrosion current density and Tafel slope) may be obtained. This method is not restricted by "liner polarizaton zone"and the corrosion current density could be directly calculated.

A series of new type Fe-Mn-Al-Cr stainless steels,which were cheaper than the steel containing 26% Mn, were designed.Their anodic polarization curves in 0.5mol/L H2SO4, 1mol/L HNO3,1mol/L Na2SO4 and 2mol/L NaOH showed that these new materials had better corrosion resistance than the former 26% Mn steel.The increase in chromium content did not monotonously improve their corrosion resistance.When the chromium content reached to a certain value ferrite appeared and the passivity of alloy decreased.XPS was applied to study the study the structure of passive film formed in 0.5mol/L H2SO4 .From the tests we wold conclude that the outer layer of the film was mainly composed of metal oxides and hydrates and its inner layer was metal oxides.Cr18Ni9Ti

The growth of color passive film formed on stainless steel 304 by A.V. passivation has been studied.The chemical composition and its distribution profile in the film have been investigated by using XPS,cyclic voltammogram.Results of the investigation show that the passive film is a bipolar duplex membrane,and the film grows in different ways as a result of the properties of the film during different periods of the alternative square wave process.Moreover,a new dynamic model is proposed for the growth of the color passive film.

The laser remelting treatment of plasma sprayed ZrO2-NiCoCrAlY graded coating on TC4(Ti-6Al-aV) alloy substrate was investigated.In order to maintain the gradual composition distribution,the laser remelted zone was controlled in ZrO2 top layer.Laser remelting treatment diminished the pores in the ZrO2 top layer and resulted in a dense microstrructure.Compared with the unmelted coating ,the ZrO2 melted zong had a higher micro-hardness and a more excellent oxidation resistance.However,owing to the graded coating being heated and cooled unevenly by the laser beam,a serious residual thermal stress was produced in the coating. Laser remelting distorted the ZrO2 grains,some coarse cracks were formed in the coating,and the adherence strength between ZrO2 top layer and graded layers was weakened.As a result,the thermal shock property of the graded coating was worsen.

The resistance distribution of oil film was measured using wire beam electrode and its effect on protective or the oil film was examined.Metal corrosion under oil film was also investigated on the basis of the surface composition analysis and its depth distribution obtained by AES.The results showed that the protective behavior of oil film was inhomogeneous,and the corrosion under oil film occured locally.The inhomogeneity and propective behavior of rust-preventing oil could be improved by introducing inhibitors.The thickness of oil film and immersion duration affected the protective behavior of rust-preventing oil.The resistance was consistent with the results of AES.

The measurements of residual stresses in Al2O3 formed on Fecralloy(Fe-22Cr-5Al-0.3Y)and in Cr2O3 formed on Co-40Cr and 3×10 17Y+/cm2 implanted Co-40Cr alloy were carried out by surface Enhanced raman Spectroscopy.The residual stresses in these two kind of oxide scales were about 2GPa.If the oxide scale cracked,oy the oxidized alloy was implanted with rare earth elements,the residual stress would decrease remarkabl.This technique also could be further developed to measure local stress distribution in the oxide scale and to apply for in-situ measurements at high temperature.

As a natural extension of our previous work,the novel wire beam electrode was used to study crevice corrosion of copper.As special electrochemical sensor.it remarkably improved the reproducibility of electrochemical measurement.The electrochemical parameters related to crevice corrosion process could be measured directly using wire beam electrode.As non-destructive and simple method,potential measurement had some advantages over other electrochemical testing methods.The crevice corrosion of copper in 5%NaCl solution was studied using a wire beam electrode.It was pointed out that the distribution of corrosion potential in crevice was inhomogeneous.At the early stage of immersion,the corrosion potentials in the crevice shifted towards positive.With propagation of crevice corrosion,the corrosion potentials in crevice began to shift negatively,and became homogeneous gradually.This process was coincident with classic theory of crevice corrosion of metal.