The sputtered nanocrystalline coating of K38G alloy was obtained by magnetron sputtering.The effect of nanocrystallization on the h ot corrosion behavior of K38G alloy at 900℃ was studied.The results indicated t hat the internal sulfidation was eliminated for the coating by pre-deposition wi th 0.8 mg/cm2 of 75%Na2SO4+25%K2SO4.Although the internal sulfides wer e still formed for the coating by pre-deposition with 3 mg/cm2 of 75%Na2SO 4+25%K2SO4,the hot corrosion resistance of K38G alloy was clearly enhanced t hrough nanocrystallization.The hot corrosion mechanism was proposed.

Through exposure corrosion test in seawater for 16 years,the “reversion” phenomena of corrosion resistance of containing chromium low alloy steels such as 921 in Yulin and Qingdao seawater were first found in China,but the reason was not understood at home and abroad.In order to study the reason of “reversion”,several methods including metallography,SEM/EDS,bacteri a identification and chemical analysis were used for entirely investigating the r ust layer on test steels and the rust layer on 921 steel exposed in Yulin seawat er was emphasized on.The reason of corrosion resistance “reversion” of some co ntaining chromium low alloy steels in seawater has been initially found out.As t he seawater corroded for a long period,the corrosion pits deeply developed and m any small metal granules fell off substrate,that greatly contributed to corrosio n rate.“Falling off” containing chromium steels was much serious than carbon s teels and non-containing chromium steel.It is considered that the corrosion dyna mic of carbon steels and low alloy steels may change from oxygen diffusion contr ol to bacteria such as SRB corrosion control at about one year.

(Ni,Pd)Al coating prepared by low pressure pack cem entation on the nickel-based superalloy M38 predeposited Pd-20mass%Ni alloy,is c omposed by β-(Ni,Pd)Al phase,and the earlier stage isothermal oxidation beh avior is investigated by TGA、SEM at 800℃-1100℃.It is found that oxidation ki netics accord preferably with parabolic law at 800℃，900℃and 1100℃,but not at 1000℃.θ-Al2O3 and α-Al2O3 are mainly the oxidation product a nd γ-Al2O3 is very little at 800℃～900℃,θ-Al2O3 and α-A l2O3 at 1000℃,and only α-Al2O3 at 1100℃.In addition,a little of T iO2 exists on the coating surface,and the content of TiO2 is increases with rising of the temperature.

A computing method for instantaneous corrosion rate on fresh surface of aluminum alloys was created in terms of corrosion character istic of aluminum alloys,and the effect of mechanical factors on the corrosion p roperties of LC4CS aluminum alloy has been studied with variation of strain rate .Results show that the natural corrosion potential of LC4CS aluminum alloy exhib its the negative drift trend under acting load of the constant strain rate,and t he larger the strain rate,the quicker the negative drift.In the state of galvani c couple with the aluminum alloy anodized,after the strain is above 0.04,the nat ural dissolution current will sharply increases.While strain rate is constant,th e instantaneous corrosion rate of the fresh aluminum alloy also increases with t he augmentation of strain.

In simulating the environment of CO2 corrosion in oilfield,the XRD，EDS and SEM techniques were adopted to study the formation an d development of CO2 pitting corrosion on N80 steel.The results demonstrated t hat Cl- anions could be enriched and nucleated at the interface between corros ion scale and matrix,which subsequently catalyzed the formation of pitting.Where as pits could also be enriched by Cl- forming approximately 3 μm enrichment l ayer at interface,thus leading to the further development of pitting.In present case,the relationship between mechanisms of anodic reaction and morphology of pi tting was discussed.

Artificial neural network (ANN) method for the data processing of carbon dioxide corrosion is proposed on the base of plenty of exp erimental data.A detailed model for predicting corrosion rate is presented,which does not need all kinds of materials and environment parameters.Only some impor tant parameters are necessary,that is,carbon content of mild steel,carbon dioxid e partial pressure,temperature,fluid velocity.The result shows that predicted va lue is generally consistent with actual value.It is proved that the ANN technolo gy is applicable for the corrosion rate evaluation of complicated system,and it also presents a new approach to evaluating remain life of equipment and developi ng the expert system.

A three-electrode electrochemical cell to study the corrosion behavior of metal under thin electrolyte was designed.With the increa sing of Cl-,and the anodic reaction was promoted,the transfer resistance and c orrosion potential decreased,the corrosion rate increased.With the decreasing of electrolyte layer thickness,the transfer resistance of zinc in 0.01 mol/L NaCl solution increased,and the corrosion rate decreased.In the bulk solution with di fferent salt,the order of effect on the corrosion of zinc from the severest to t he lightest is Na2SO4,NaNO3 ,Na2CO3 and NaCl,while under thin electrol yte,the order is NaCl,Na2SO4,NaNO3 and Na2CO3.

Plating rare earth chromium on stainless steel appl ied in hydraulic turbine,by means of the operation converting electrodes periodi cally,was carried out.The plating layer consists of metallic matrix and second p hase particles of rare earth sulphates or carbonates,its thickness is about 0.3m m,its microhardness is from Hv900 to 1000.The results of anodic polarization cur ves indicate that the corrosive resistance of plating layer is 7～8 times to tha t of stainless steel substrates.When an imitating small hydraulic turbine made u p of different materials was rotated in the slurry of 60% water and 40% sands,th e resistance of plating layer to cavitation erosion and abrasion is about 28 tim es to that of stainless steel,and is 10～12 times to that of plasma-nitrided sta inless steel.The results of hydraulic electricity generation indicate the servic e life of plated hydraulic turbine is 3～6 times to that of stainless steel hydr aulic turbine.

In order to understand the effects of hydrogen sulf ide and white deposit in discharged waste water from oil platform on the corrosi on and protection of the steel structure of W11-4 oil platform,a study was made by collecting the water samples,analyzing the concentration and distribution of hydrogen sulfide in the samples and the composition of the white deposit in the sea around the platform,and investigating its impact on the corrosion behavior o f carbon steel.The results indicate that hydrogen sulfide mainly concentrates in the region of the sea near the surface,with a maximum of 19 mg/L,and its concen t ration greatly depends on the sea flow.The white deposit is the secretion from t he attached marine organisms on the platform structure.It is also clarified that hydrogen sulfide and white deposit have no impact on the corrosion and protecti on of the steel structure of the oil platform.

The effects of sulfate reducing bacterial (SRB) on corrosion of 1Cr18Ni9Ti stainless steel in different Cl-content soils with an d without SRB have been studied， Using bacterial analysis,weight loss,electroch emical impedance spectroscopy(EIS),scanning electron microscopy (SEM) and EDAX.T he results showed that corrosion rate in different Cl- content soils with SRB are larger than those in soils without SRB.Corrosion pitting of 1Cr18Ni9Ti stai nless steel occurred in soils with SRB，and corrosion pitting depth of 1Cr18Ni9T i stainless steel increases with the increasing of Cl-content of soils with S RB.The results indicate that corrosion rate of 1Cr18Ni9Ti stainless steel incre ases in soils with SRB.For no pits of 1Cr18Ni9Ti in soils without SRB,the sluyt ers diagram of EIS are composed of single capacitive loops.For the pits propaga tion of 1Cr18Ni9Ti in soils with SRB,the sluyters diagram of EIS are composed of two capacitive loops.

A prediction model of corrosion damage for aircraft structure and 1Cr17 stainless steel under a varied corrosion environment based on artificial neural net was developed and the nonlinear relationship between a verage corrosion rate,average corrosion loss weight,corrosion depth,corrosion te mperature,immersion duration,concentration was established based on BP learning algorithm.The corrosion characteristic quantity (CCQ) such as surface area,depth and so on can be predicted by means of the trained neural net from the data.The results show that,the model has relative good prediction accuracy and flexibili ty than the gray theory GM(1,1) model and the Logistic model.The prediction mode l based on BP learning algorithm of corrosion damage for aircraft structure is f easible and effective.Thus,by virtue of the prediction model,the future corrosio n status and service duration of engineering structure can be evaluated.

Some fundamental methods used in natural environmen tal corrosion data processing are briefly reviewed in this paper,such as statist ics analysis,curve fitting and correlation analysis.The basic principle and calc ulation method of some moderrn mathematics methods,for example,grey theory,fuzzy mathematics and artificial neural network are expounded systematically,too.Furt hermore,this paper focused on the typical application of grey model forecast,art ificial neural network,cluster analysis,pattern recognition,grey relational anal ysis,etc,in national natural environmental corrosion data processing,regularity research and corrosivity evaluation.