The relationship between corrosion image grayscale and pit depth was studied based on experimental data. A good linear relationship was observed and their relatioship coefficient was high up to 0.95 for corrected image of isolated and regulation holes by double-direction scanning. For actual corrosion images, the relationship was still linear under confidence leel 0.95. however, the complex deep pits might cause error and corresponding image grayscale became higher in values(brighter). Moreover the correlation curve of statistical distribution between gray and pit depth showed two lines with different slopes, which turning point was 0.045cm. Therefore it could be decided that corrosion morphology diagnoses based on image grayscale were more suitable for early corrosion stages. Inaddition, the relationship between image grayscale and corrosion parameters was also investigated and the results showed that image grayscale range was good characterization for average corrosion rate and max. pit depth, that they had good linear relationship under confidence level 0.95.

The photoelectrochemical measurement of stainless steel in simulated cooling water shows that, the passive film on the stainless steel exhibits n-type photoresponse, and the peak of absorption happens at 310nm. The passive film on stainless steel starts to generate photocurrent at potential about -0.35V. As the potential rises, the photocurrent increases, and the bandgap energy Eg of the passive film fall. The addition of sulfide in the simulated cooling water can increase the photocurrent, and reduce the Eg values of the passive film on stainless steel. The greater the concentration of the sulfide is, the larger the measured photocurrent and the lower will be the Eg. That is attributable to the fall of the film resistance of the passive film and the decrease of content of chromium oxides in the passive film.

In this paper, an electrochemical sensor to detect corrosion in aquatic environment was designed and set up.But contact and angular contact welding seam corrosio detection sensors were designed respectively. Based on local enclosure theory an enclosed electrolytic cell was built up by contacting the front section of insulated cavity with the surface of the component to be tested. Magnets were employed as contacting fix up on the structre surface. Current enclosing capability of the sensor was erified by the experiments. Employing the sensor developed, measurement were carried out at welding seam and different locations of the base metal on simulating welded specimens in NaCl solution of 3.5%. The results show that Rpof welding seam and base metal exhibit different trends against time, and both EIS spectrums diferentiate with each other evidently. It shows that the corrosion situations at different sections can be well distinguished by the sensor.

In this paper, corrosion inhibition of 1,4-butynediol in epoxy coatings was studied by means of electrochemical method and IR spectrum. Experimental results showed that the inhibitor obviously increases the corrosion- resistance of epoxy coatings. When the amount of 1,4-butynediol corrosion inhibitor is less than 0.5mass% in the coating, the impedance of coating increases with addition of the corrosion inhibitor. Through the impedance data which is fitted by ZSimpwin software and analysis of the IR spectrum, we suggest that the incomplete corrosion inhibitor film with double bonds is formed between coating and substrate. The inhibitor mechanism of the corrosion inhibitor film was also discussed by means of electrochemical method.

BIA, BIOHA, BIMHA and BIMMA were synthesized in the laboratory and their influence on the inhibition of corrosion of A3 steel in 1 mol/L HCl solution was studied by weight loss and electrochemical measurements. The obtained result showed that four compounds were good inhibitors and performed pretty inhibiting efficiency for A3 steel in 1 mol/L HCl solution. The inhibition efficiency of the tested compounds was found to decrease as follows: BIA>BIMMA>BIOHA>BIMHA. It was found that the inhibition efficiency increases with an increase in the tested compounds concentration but decreases with an increase in temperature. Compounds were imxed - type corrosion inhibitors, but its inhibition of the anodic reaction is a little better. Thermodynamic paarameters such as adsorption heat, adsorption entropy and adsorption free energy were obtained from experimental data of the inhibition process at four temperatures ranging from 40℃ to 70℃. The adsorption processes are exothermic reaction and belong to physical adsorption. The langmuir isotherm is followed.

Inhibition for copper alloy in high concentration chloride solution has been explored with in-situ graze ellipsometry and linear sweep voltammetry(LSV) technology. The results show that the change of parameter behind of current change and the shift of corrosion productions into solution were blocked by the BTA layer. With the corrosion production accumulated, the increase of overpotential on anode was necessity, and potential difference of corrosion reaction was decreased.Thus the rate of corrosion reaction was delayed and the corrosion resistance of copper alloy was increased.

The mathematical nodel of cathodic protection potential distribution on the exterior of tank bottom is established and calculated by using FLUENT software. the effects of soil resistivity, polarization characteristic of tank bottom, depth of anode, distance between anode and tank on cathodic protection potential distribution of tank bottom are studied. Calculated results are compared with measured data and there is good agreement between them.

Baesd on the database of a corrosion project，which was a sub-project of the international cooperation programme RAPIDC（Regional Air Pollution in Developing Country）， Dose-Response Functions（DRFs） of carbon steel，zinc and copper were set up by the combined methods of grey relation analysis and non-liner regression. The DRFs could reflect the mechanism of atmospheic corrosion by some extent. The results showed that the obtained DRFs well fitted the experimental data and had relative simple expression，therefore they could be used to calculate the economincal loss of material corrosion at regional scale.

Antisepsis of cathodic protection with Zn as sacrifice anode to X70 steel in weak acidic solution with H2S was studied by means of static weight loss method and scanning electron microscope. And inhibitive effect of 4-hydroxy-2-mercapto-6-methyl-primidine(HMMP) to the corrosion of X70 steel under the same condition was investigated by means of electrochemical impedance spectroscopy and potentiodynamic polarization curves. The results show that the antiseptic result with Zn as sacriice anode to X70 steel in weak acidic solution with H2S is excellent. HMMP belongs to mixed inhibitors that mainly restrain the anodic process, the inhibition increases gradually with the increasing of its concentration within the range of concentration studied.

Stress corrosion cracking (SCC) behaviors of 16Mn and 16Mn(HIC) steels and their melted samples in acid H2S solution are investigated, with slow-strain-rate test(SSRT) and U-bent-specimen test.The results shows that both 16Mn(HIC) steel and 16Mn steel as well as their welded joint materials are all easy to subject to SCC damage in NACE solution, and the cracks of all specimens are HIC-induced transgranular cracks. The resistance to SCC of 16Mn(HIC) steel is better than that of 16Mn steel, as well as the behavior of weld joint of 16Mn(HIC) steel also performs better than that of 16Mn steel;the susceptivities of welded specimens of these two kinds of steel are much higher than those of their base materials, and heat treatment can improve the abilities of welded joint materials to resist SCC.

A nanocrystalline Ni-30Cr-8Al-0.5Y coating was deposited on a Ni-base superalloy by magnetron sputtering. Post-aluminizing was performed on the sputtered coating to improve the corresponding high-temperature oxidation resistance. The isothermal oxidation behaviors of the sputtered coating with and without aluminizing at 1000℃-1100℃ have been investigated using TGA, SEM/EDS, XRD and EPMA, respectively. The results indicated that the sputtered NiCrAlY coating possessed excellent oxidation resistance at 1000℃. Because of the excessive consumption of Al in the coating, it lost protective ability at 1100℃. The mass gain of the aluminized NiCrAlY coating was a little higher than that of the sputtered coating due to the formation of the rapid growthθ－Al2O3 phase at 1000℃. At 1100℃ the oxidation resistance of the latter was better than that of the former as a result of the formation of a continuous and protective Al2O3 scale.

The Al－Si coating on the surface of K4104 superalloy were prepared by using slurry process. Two different coating were formed by changing the CrO3 content of agglomerant. According to HB5258－2000, the high temperature performance of these coating have been investigated by high temperature oxidation test.The oxidation kinetics curve was drawn. The surface morphology of the Al－Si coating were studied by using SEM. The results indicate that the Al－Si coating on the surface of K4104 superalloy have transformed to compact oxidized film α－Al2O3 and β－NiAl compound scale in the process of high temperature oxidation and all of them have good adhesivity. The Al－Si coatings have excellent high temperature oxidation resistance.

Stress corrosion cracking and pit corrosion of steam generators In Tianwan Nuclear Power Plant is described,The cause of corosion is preservation method which is not correct during transportation and installation, measurement and suggestions for safe operation of steam generator is proposed. Steam generators should be protected dryly during outage, it is necessary to adjust scour project by using KOH-N2H4 alkali liquor instead of NH3-N2H4 alkali liquor,to reduce the content of deliquescent -oxygen and Cl- in water, to increase the pH value of the liquor, to purge of equipment regularly and to install reverse infiltration equipment in chemistry water treatment system.