A numerical method has been developed to extract the composition-dependent interdiffusivity of Ni and Al from the concentration profiles in the aluminide coatings prepared by pack cementation. The procedure is based on the classic finite difference method(FDM). In order to simplify the model, the effect of some alloying elements and carbides on interdiffusivity was negligible. Calculated results indicated that interdiffusivities of Ni and Al in aluminide coating on K465 superalloy strongly depended on the composition and were evidently less than those on pure nickel substrate. The reasons for decreasing of interdiffusivities in aluminide coatings on K465 superalloy were briefly discussed.

An investigation on the changes in open-circuit-potentials of passive metals in seawater was made with electrochemical technology and epifluoresence microscopy. It was found that in natural seawater, the open-circuit-potentials of passive metals shifted in noble direction gradually. The in-situ microscope observation showed that biofilm gradually formed on the metal surfaces with the increase of open-circuit-potentials and the change in bacteria number on metal surface was in the same manner with the ennoblement of the open-circuit=potentials. However, compared that in natural sea water, both open-circuit-potentials and bacteria number are not changed in sterile seawater. In addition, open-circuit-potentials and bacteria number for coppper clectrode were almost not changed no matter in natural or in sterile seawater. Moreover, the double capacitance of passive metals decreased woth time when immersed in natural seawater, while it remained almost unchanged in sterile seawater due to the decrease in dielectric constant with the formation of bilfilm in natural seawater. Above results strongly supported that bacteria attachment and growth of bilfilms were the cause for the ennoblement of open-circuit-potentials of the passive metal.

The effect of environment corrosion and salt fog on fatigue properties of 3 types of bolted joint structures and 12 kinds of protective measures of LY12CZ Al- alloy plate typical bolted lap joints was studied by an accelerated corrosion test. Several protective measures for detail structure improving properties of LY12CZ Al-alloy bolted structure against environment corrosion damage were presented. the results showed that environmental corrosion worsened the fatigue properties of the bolted joint structures. The anti-corrosion damage and fatigue properties of bolted joints can be generally increased to different degree if appropriate protective measures were applied to the detail structure of bolted joints. installed bolt with marine grease and wet installed bolt with primer studied in the paper were more effective to improve anti-environment damage properties of the bolted joints. Their fatigue properties were increased obviously compared with those not treated in the testing environment. Their fatigue life were increased by 78.36% and 83.45% respectively, and their DFR value were increased by 15.09% and 15.88% respectively.

Duplex stainless steel is composed of ferritic and austenitic phases, which have different crystal structure and element component, thus in different solutions, ferrite and austenite demonstrate different dissolutio rate, that is , selective dissolution. In this investigation, the potentiodnamic polarization experiment was carried in nitric acid and hydrochloric acid mixture, and mixture of nitric acid and sodium chloride, nitric acid and ferrite chloride as well. After the experiments, SEM and EDS were used to distinguish and analyze the morphology differencs of the two phases. The results show that in the solutions containing nitric acid, adding hydrochloric acid and sodium chloride will enhance the selective dissolution of two phases, while adding low concentration of ferrite chloride will decrease the corrosion difference between ferrite and austenite, but the phenomena vanish with the increasing of the concentration of ferrite chloride.

In this work, effect of hand sweat composition on the corrosion behavior of AZ91D magnesium alloy was investigated. the pH value of the test solution was increased and the corrosion rate of AZ91D aloy decreased by adding urea, while the corrosion rates were accelerated by adding lactic acid or NaCl. The synergistic effect of lactic acid and NaCl played a key role in the corrosion process of AZ91D alloy in hand sweat In water or urea containing solutio, the kinetic curves of hydrogen evolution were the functins of "logistic model". In the NaCl or lactic acid containing solution, the kinetic curves of hydrogen evolution were the functions of "polynomial model".

RuTiSnMn/Ti anode prepared by thermal decomposion was tested at a current density of 4mA/cm2, characterized by cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS) in 35g/L NaCl solution, 20g/L NaOH solution and simulated porous water, in combinatin with surface morphology observation by scanning electron microscopy(SEM0.Results showed that anode exhibited enough ability to tolerate the chlorine evolution and the oxygen evolution. The formatin of an insulating layer of TiO2 at the interface between the metallic base and the active coating resulting in the increase of oxide film resistance, the catalyst consumption induced the increase of charge transfer resistance of faradaic process evidently, which lead to the deactivity of the anode.

Simulated autoclave is employed to study the corrosion process of three kinds of oil well steels in CO2 environment with varying CO2 partial pressure. The effect of the CO2 partial pressure on the average scale thickness and crystal grain size of the scales is studied by using scanning electron microscope(SEM).The results show that, the cross-section of the corrosive product scales of the three kinds of steels are doublelayers in the structures, the variation of average scale thickness for the three kinds of steels with CO2 partial pressure is in the similar manner, of which the maximum average scale thickness appears at the CO2 partial pressure about 6.89MPa and then decreased rapidly. The variations of the average crystal grain size with CO2 partial pressure for the three steels exhibit two peaks and a valley in between; however the CO2 partial pressures corresponding to the peaks and valley and crystal grain sizes for different materials vary, and crystal grain sizes of the three steels with CO2 partial pressure decreased quickly beyond the peaks.

By means of constant load tests and slow strain rate tests(SSRT), the SCC behavior of aluminized 304 stainless steel in boiling 42% MgCl2 solution was studied. The SCC mechanism of aluminized 304 steel has been analyzed This paper mainly discusses the influence of different test means on the evaluation SCC susceptibility of aluminized 304 steel. Two test methods both show that aluminizing treatment improved the resistance to SCC of SUS 304, the mechanisms were the environment covering action and the electrochemical protective action of the aluminized layer. The two methods were the same in appraisal of SCC properties of aluminized 304 steel, the more the SCC target of constant load test(σth ),the more the SCC target of SSRT( δi),but the two means was different in the formation of fracture surface. The fracture of constant load tests was transgranular SCC mode, whereas the SSRT fracture surface was tough and without SCC fracture characteristics.

Tensile tests and slow srain rate tests(SSRT) are used to investigate the mechanical behaviors of X70 pipeline steel after electrochemical hydroge charging.The experimental results show that hydrogen charging has little influence on the tensile strength of X70steel and decreases the plasticity of X70steel, thereby the fracture ductility and the fracture strength reduce considerably. After static electrochemical charging with hydrogen, the plastic properties successively decrease with the increase of pre-charging time. At the slow strain rate tension(SSRT) condition, dynamic electrochemical charging with hydrogen decreases the plasticity of X70 pipeline steel considerably. Analysis on the fracture morphology by SEM indicates that the fractograph exhibits typical ductile dimple fracture pattern after static electroxhemical charging, and the diameter of dimple becomes smaller compared to the uncharging specimen. The fractograph of dynamic electrochemical charging during the SSRT displays with a quasi-cleavage mode.

Electroless Ni-Zn-P alloy deposits from an alkaline bath cntaining NH4Cl as a buffer agent and sodium citrate as a complexing agent was investigated. The effects of deposition parameters9pH,concentration of ZnSO4.7H2O and temperature)on the plating rate and the deposit composition was examined respectively. It was found that the presence of zinc in the bath has an inhibitory effect n the alloy deposition. As a consequence, the percentage of zinc in the electroless Ni-Zn-P alloys never reaches high values. The structure and the crystallization behavior of the deposit has been characterized by XRD and DSC. The results show that the as-plated deposits consist of mainly an amorphous structure together with some cubic phase Ni. The deposits crystallized into Ni3P at 384.8℃ and transformed into Ni5Zn21 at 580.7℃. The weight loss test and the anodic polarization measurements of the as-plated and the heat-treated deposits in 3.5mass% NaCl solution(pH7.0) indicate that the two deposits show good corrosion resistance, especially the as-plated deposit.

Corrosion protection of cold-rolled steel(CRS) was investigated with dispersed emeraldine base(EB) form of polyaniline. EB was dispersed in deionized water or aqueous NaCl and then deposited on the surface of CRS. A compact oxide film was formed on the surface of treated CRS and proved by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy(SEM0, which shifted the corroson potential by 200mV in noble direction and significantly decreased the corrosion current density . It was attested that EB film alone could not offer effective corrosion protection for its bad stability, while EB dispersed in epoxy coating holds good its redox characteristic and provide excellent anti-corrosion property by passivating the CRS. The barrier effect of the epoxy coating was reduced with the incorporatin of EB particles, therefore a topcoat with good barrier performance was needed on the EB/epoxy coating (EBd/EP). It was exhibited that a good barrier topcoat remarkably enhanced EBd/EP's corrosion protection performance.

Two kinds of new triazole compounds were synthesized. Their inhibiting behavior on carbon steel in 1.0mol/L hydrochloric acid solutio was investigated by means of weight loss, potentiodynamic polarization and AC impedance methods. The results show that the triazole derivatives suppress both the anosic and cathodic process and the inhibition effect is caused by geometrical blocking of the metal surface by adsorbed inhibiting species. The investigated triazole compounds inhibit corrosion by adsorption mechanis and the adsorption leads to the formation of a protective chemisorbed film on the metal surface which suppresses the corresponding corrosion reaction. The synthesized triazole compounds are found to be excellent corrosion inhibitor for carbon steel in hydrochloric acid.

Lignite and peat show acid when mixing with water. The corrosion acton of carboxyl and phenol hydroxy of lignite and peat on low-alloy steel was studied. Prepared solutions and saturated coal samples of lignitd and peat respectively served as the media of corroson experiments, and the pH levels were measured. The corrosion mechanism of 27SiMn low-alloy steel in these media was analyzed through measuring polarization curves and infrared spectrums. The results show that thecarboxyl and phenol hydroxy of lignite accelerate the corrosion of 27SiMn low-alloy steel, while the carboxyl and phenol hydroxy of peat have inhibitory action on anodic dissolution of 27SiMn low-alloy steel because of the existence of oxy functional groups compound with bitumen.

The progress on the study and application of zinc-rich paints(ZRP) in the recent 70years has been reviewed. The design principle of ZRP and the problems of ZRP as topcoat systems and primer of multi-coatpaint systems were introduced The performance of different kinds of ZRP was compared. A brief introduction of zinc powder in ZRP was presented. The electrochemical study on ZRP was also summarized.