The effects of magnetic field and dichromate ion wi th different concentrations on anodic polarization behavior of iron in 0.5 mol/L sulfuric acid were studied by means of potentiodynamic polarization measuremen ts.Results showed that less than or equal to 0.02 mol/L dichromate did not chang e the configuration of the anodic polarization curve; anodic polarization curve s showed drastic change of the slope for E-i curve when dichromate concentra tion was more than or equal to 0.05 mol/L, and such drastic slope changing occurred at more negative potential and low current density when dichromate concentration increased.Current densities would decrease, remain unchanged ,and increase in t he presence of magnetic field in certain potential ranges, and such magnetic fi eld effect was closely related to the contribution of the cathodic and anodic re actions and the type of rate controlling steps for each reaction. Magnetic fie ld could accelerate the mass transfer process at electrode/solution interface, t hus obviously increase the current density at the slope drastic changing section of the anodic polarization, even eliminate such a section.Magnetic field could induce new current oscillation, change the pattern of the pre-existing current oscillation, or even eliminate current oscillation.Activation-passivation transi tion occurred at more noble potential and higher current density in the presence of magnetic field than that in the absence of magnetic field.The model of polar ization curve with magnetic field was derived based on taking into account of th e possible active dissolution,film formation and film dissolution reactions in a nodic process, the effect of cathodic reactions, and the effect of magnetic fiel d on mass transfer processes in cathodic and anodic reactions.The model develope d here matched well with the experimental results that magnetic field resulted i n different effects on current densities in different potential ranges.

Surface coking morphology of pure nickel and its correlative factors w ere investigated systematically.Results reveal that the coke deposited on surf ace of pure nickel includes the filamentary coke,the particlelike coke,and th e filmlike coke.Deposition of the filamentary coke happens at approximate 800 ℃ and is closely dependent on the nickel substrate.Preoxidation markedly aggr avates the deposition of the filamentary coke on surface of pure nickel.Either raising the coking temperature or prolonging the coking time results in change o f the coking mechanism,and the deposited coke tends to show a particlelike mor phology.Since the particlelike coke is derived from a series of gasphase rea ctions,it bears no relation to the nickel substrate naturally.The filmlike cok e is only deposited at the initial coking stage.Both the dissolution/precipitat ion mechanism and the direct nucleation/growth mechanism may make a contribution to development of the filmlike coke.Restraining the formation of the filament ary coke can be beneficial to alleviate the totally coking degree on the nickel surface.

Design and synthesis a series of LCMA compounds.The inhibiting action of LCMA in H2S-containing sulfuric acid solutions has been studied by electrochemical methods.The results showed that LCMA could adsorb in parallel direction and retard anodic and cathodic reactions of iron in H2S med ia through negative-catalysis effect.The high inhibiting efficiency of LCMA was closely correlative with the structure of function groups and the length of carb on chain.LCMA with less hydroxyethyl group and longer carbon chain could exhibit more excellent inhibiting effect.The strong inhibiting action of LCMA in low co ncentration was attributed to the high coverage degree of LCMA molecule,which wa s resulted from multi-adsorption.

Simulated occluded cells were used to study organic anions such as C12H25SO-4、C12H25C6H4SO-3 、 C12H23OO- migration and their effects on occluded corrosion of mil d steel (A3) in 001mol·L-1NaCl solution at 50℃It was found that they migrated into the occluded cell as anodic current passing the cell, the quanti ty of migration increased with the time and the concentration, the order of migr ation quantity was：C12H23OO- ＞C12H25C6H4SO-3 ＞C12H25SO-4 at a concentration of 001mol·L-1,whi le the migration quantity of them were same when the concentration were 0002 a nd 0005 mol·L-1They all can retard the migration of Cl-,and had the same effects on the migration of Cl- at the concentration of 0002 and 000 5mol·L-1,but it was the best when the concentration was 001mol·L-1 ,C12H23OO-,and C12H25C6H4SO-3 was the better They had no effect on the pH fall of the OCC solution.

Oxidation behavior of the particle reinforced Al2 O3/SiC/(W,Ti)C composite ceramic tool materials has been studied in detail,as well as the effect of the oxidation on the flexural strength of the material.It is shown that the weight gains in the static oxidation of the material under ai r atmosphere obey the parabolic law.The energy of activation of the material dec reases with the increase in the content of SiC and (W,Ti)C.Residual stresses in the oxidation film can be released with the form of the viscous flowing at high temperature.Therefore,the speed of the oxidation is lowered,and then the oxidat ion resistance of the material can be enhanced to some extent.It is found that t he appropriate oxidation is effective for the improvement of the flexural streng th of Al2O3/SiC/(W,Ti)C ceramic tool material.

Epoxy powder coating resistance to corrosion medium in high temperature solution is investigated using static immersion method and infrared spectroscopy, analyz ed medium transport behavior between 100℃ to 120℃ and between 100℃.Experience results show:(1)When the medium temperture is higher than Tg,epoxy powder coating resistance to corrosion medium is worse.When the medium temperature is lowe r than Tg, Epoxy powder coating resistance to corrosion medium is better.( 2)Epoxy powder coatings in high temperature solution(100℃≤T≤120℃)have sa me good alkali-resistance as that in low temperature solution(T＜100℃).

Galvanic corrosion results of steel couples with various free corrosio n potential difference and surface area ratio of cathode to anode in seawater ha ve been obtained.Galvanic corrosion behavior of the steel couples was discus se d.Equation of anodic corrosion rate of steel couples in seawater were examined a nd simplified.With the increase of free corrosion potential difference and surf ace area ratio of cathode to anode, the anodic corrosion rates of steel couples increase.The relationship between anodic corrosion rate of steel couples and s urface area ratio of cathode to anode is nonlinear.With the increase of surf ace area ratio of cathode to anode, the anodic corrosion rates have a limit.With th e increase of corrosion potential difference between cathode and anode and the d ecrease of area ratios of cathode to anode, corrosion rate of cathode decreased. The simplified equation of anodic corrosion rate of steel couples in seawat er has a good consistence with the experimental results.

The oxidation of Ptmodified aluminide coatings on nickelbase superalloy IN738 has been studied in static air at 1100℃ up to 14 00 h.The presence of Pt significantly suppressed the formation of γ′Ni3Al, promoted selective oxidation of aluminum by preventing the transport of other el ements in the substrate outwards to Al2O3 scale and forming purer,slowlygr owing and adherent Al2O3 scale.

Internal oxidation treatment were carried out in an internal oxidizing apparatus for a Cu-0.75%Al powder sintering alloy, and microstructure were inve stigated by means of SEM, TEM and X-ray. Results showed that the internal oxides of the spherical α-Al2O3 particles were distributed within grain and the n etw ork oxides existed at grain boundary among internal oxidation layer.Concentratio n of ［Al］,［O］ atoms were regularly distributed within the layer. Through int ernal oxidation treatment, the formed internal oxides produced the volume expand ing, which improved the densification of Cu-Al powder sintering alloy.