A new kind of electrochemical sensor was used for measuring the permeation rate of atomic hydrogen(H permeation current) through the sensor in 5% HCl solution containing Fe(3+) at different concentrations.The susceptibility and mechanism of brittle fracture of A3 mild steel were studied by slow strain rate tensiletechnique (SSRT), scanning electron microscope (SEM) and cathodic/anodic polarization measurements.The embrittlement susceptibility of the steel in the solution was expressed as the index of embrittlement(F%).The results showed that the fracture mechanism of the steel in 5% HCl aqueous solution containingFe(3+)would be changed from hydrogen induced cracking (HIC) to anodic dissolution in nature with theimcrease of the concentration of Fe(3+) in the solution.

Ni3Al-Mo base alloy IC-6 was aluminized by high activity process and the specimen was subsequentlydiffusion treated under argon atmosphere. The microstructure and chemical composition of the coatingwas investigated by optical microscopy, XEM, EPMA and XRD. It was found that molybdenum in thecoating is present as a second phase Mo3Al. The oxidation resistance of IC-6 alloy was improved markedlyby the aluminizing coating. The protective oxide film of A12O3 prohibited the formation of molybdenumoxide. During the cyclic oxidation test, the aluminized IC-6 alloy showed improved oxidation resistancebecause of the absence of the polymorphic change of NiMoO4 phase. The dissociation of β-NiAl phase inthe aluminizing coating has not been observed after 300 hours under isothermal oxidation or 100 hoursunder cyclic oxidation in air at 1000℃. It can be concluded that the coating possesses good enoughprotective properties.

The morphology and microstructure of Ni-La2O3 codeposited films were studied by means of metallograph, electron probe microanalyzer (EPMA) ,transmission electron microscope (TEM) and high resolutionelf3ctroli microscope (HREM). It was found that the amount of La2O3 in the Ni codeposited film lucreasedwith increasing amount of La2O3 particles in the plating bath, and that the presence of La2O3 particlesin the films resulted in the reduction of the nickel grain size. Two kinds of morphologies of codepositedLa2O3 inclusions were observed in the nickel composite film: one consisted of the dispersed nanometer-sizeparticles, most of which were less than 50 nm in diameter; the other was micrometer-size " agglomeratedclusters" which were comprised of nanocrystallites less than 10nm. Since the Ni-La2O3 codeposited filmon Ni-base superalloy was prepared as the matrix layer for diffusion aluminizing to obtain La2O3-modifiedaluminide coating, the effect of the La2O3 inclusions in the Ni-La2O3 films on the microstructure of thealuminide coating and its oxidation behavior was also investigated.

The isothermal oxidation behavior of molybdenum-containing Ni3Al-Fe base alloy was studied at 900-1100℃ in air. The structure and composition of the oxide scale were investigated by X-ray diffraction,scanning electron microscopy and electron microprobe analyzer etc. The reaction energy of oxidation wascalculated as 42.7kJ/mol. The microstructure of the alloy is composed of γ and β phases. The scale onγ phase was composed of several oxide layers, revealing crystallographic voids. Mo and Fe in γ phaseincreased the oxidation rate of Ni3Al and reduced the adhesion and cohesion of the oxide scale. It is shownthat the oxidation of γ phase followed a parabolic rate law, and unlike other Ni3Al alloy, its oxidationwas controlled by the diffusion of Fe in the oxide layer of Al2O3. The scale on β phase was composed of acontinuous, compact Al2O3 oxide layer, and Mo and Fe in the β phase is harmless to oxidation of β-NiAl.

The corrosion behavior of xylene unsaturated polyester resin (XUPR) was studied in 30% HNO3 solution at ambient temperature and 90℃ by using weight-loss testing, corrosion layer thickness measurement,SEM and FT-IR techniques, etc. The results showed that, weight-loss and corrosion farer thickness of thesamples inereased initially with immersion time, then went up to a certain value that was dependent ontemperature. The corrosion mechanism was proposed. Physical absorption and chemical reaction mighttake place on the specimen surf are during immersion. The surface layer produced could act as a barrierto further diffusion of HNO3 into the specimen. It could be concluded that XUPR is a good material ofcorrosion-resistance to 30% HNO3 solution.

The finite element method was adopted to compute the distribution of hydrogen concentration inweld overlay structures. Comparison between the computed results for the hydrogen diffusion behaviour under electrolytic hydrogen charging and those under gaseous hydrogen charging in autoclave was carriedout. The results showed that in both cases the peak hydrogen concentrations near the fusion line aresimilar and can be reached in a shorter time under electrolytic hydrogen charging.The factors affecting hydrogen-induced disbonding were studied through a serieS of theoretical computation, and the influence of different specimen conditions and different test conditions were analyzed.The results showed that the increase of current density, the prolongation of charging time and/or thethinning of the base metal will inerease the peak hydrogen concentration and enhance the tendency ofdisbonding.

The effect of the ratio of permeation area to the specimen area ζ and the shape of the specimenon hydrogen permeation of copper has been studied using the Devanathan's double electrolytic cell. Theresults show that only when the permeation area ratio ζ exceeds a critical value ζc, which depends on thegeometric shape, can the hydrogen permeation curve and the apparent diffusion coefficient be measured.The ζc has the smallest value for a circular specimen and the highest value for a polygonal one. Theapparent diffusion coefficient measured increases with increasing permeation area ratio ζ. A circularspecimen with a large permeation area ratio is the most ideal one for hydrogen permeation test at roomtemperature.

A concept of the so-called comprehensive factor, N, which can quantitatively describe atmospheric corrosivity is suggested in this paper. N consists of wetness factor, corrosiveness facter and rain acidityfaCtor. The mathematic relationship between N and the corrosion rates of carbon or low alloy steels forthe first year has been found as followsR = A + B ×logNwhere R is the corrosion rate of carbon or low alloy steels, and A and B are regressive coefficients.Prediction equations for atmospheric corrosion of carbon and low alloy steels have been proposed.

The oxidation and hot corrosion of NiAl-20Fe alloy at 850~1150℃ and 850~950℃ respectivelywere studied. It was shown that both oxidation and hot corrosion of the alloy obey the parabolic ratelaw. The addition of 20at% Fe to intermetallic compound NiAl caused a little drop in oxidation resistance,but a great decrease in resistance against hot corrosion. Compared with NiAl-30Fe, due to a decrease inFe content, an increase in Al content and the addition of Y and Ce, the NiAl-20Fe alloy showed someimprovements in oxidation resistance but little benefit in hot corrosion performance.

The fractoraphy of fatigue in air, in methanol or during dynamic hydrogen charging for the Ti-24Al-11Nb alloy was studied. The results showed that both hydrogen and methanol could promote fatigueof the alloy. The △K(th) decreases and the da/dn increases in the followins order: in air, in methanol,dynamic hydrogen charging medium. The prisms appeared on the fracture surface of corrosion fatigueduring dynamic charging indicated that hydrogen induced cleavage occurs along the base plane (0001)and prism planes {0110}. Some small dimples and some secondary microcracks of 3~6 μm in length onthe hydrogen induced cleaVage planes suggested that the cleavage cracks nucleated preferentially in α2platelets.

A ceramic coating consisting of ZrO2, Y2O3, SiO2 and B2O3 was prepared using plasma spraying onthe surface of carbon felt/carbon comosites. The coating remarkably improved the oxidation resistanceof the composite below 1000℃ in air. Careful observation of the microstructure of the composite afteroxidation revealed that oxidation started from carbon felt on surface and that the carbon felt was oxidized more rapidly than the carbon matrix. The relationship between in K and 1/T on Arrhenius plot wasexamined. The linear dependence from 600℃ to 900℃ for the uncoated specimens indicated that theoxidation process was governed by single mechanism. For the coated specimens the flection at 760℃InK ~1/T plot suggested a change of oxidation mechanism. Thus two dufferent activation energy valuescould be evaluated.A model that explains the oxidation behaviour of the coated carbon/carbon compositeis proposed.

S-TEN steel surface was investigated by auger electron spectroscopy (AES) and scanning electronmicroscopy (SEM). Elements S and Sb have segregated on the surface of the hot rolled S-TEN steel, andtheir contents are 4.24 at% and 0.50 at% respectively. The surface segregation of the elements S, Sb andCu has also been found after immersion of the sample in sulphuric acid. The segregation layer of sulphur isthicker than that of copper.The enrichment of Cu, S and Sb in surface layer is beneficial for the resistanceof the S-TEN steel to sulphuric acid dewpoint corrosion.

The structure, adherence and corrosion resistance of aluminium coating electro-plated on brass from amolten salt bath consisting of AlCl3-NaCl were studied. after heating in the temperature range of 300-380℃, the grains of the aluminium coating were refined, its compactness increased, Cu and Cu9Al4 phaseswere formed and corrosion resistance was improved.