By means of electrochemical and trace amount analysis techniques the dezincification behavior of α+β biphase brass in a deaerated acidified solution of sodium chloride under condition of continuous introduction of Cu~+ into solution was studied. The changes of the indicator electrode potential with time could provide information of the copper deposition on the brass surface. Similar results were obtained by trace amount analysis method. Experimental results show that corrosion of biphase brass under experimental conditions follows the dissolution-redeposition mechanism. It was shown that the reduction of Cu~+ was compensated by the dissolution of Zinc from brass. Thus, serious dezincification took place on the surface of biphase brass. Experimental results indicated that the limiting concentration of Cu~+ which caused copper redeposition was below 10~(-4) M. Apparent rate constant of copper redeposition was 3.7×10~(-4) sec~(-1). A model was suggested and compared with experimental results.

The infiltration of NiCrBSi and CoCrW coating alloys on various base steels has been investigated systematically in this paper by means of vacuum fusion,scanning electron microscope,electron probe and X-ray diffraction techniques. A quintic equation between the condensation contact angles and the boundary face concentration difference in Fe element has been proposed by measuring the condensation contact angles of melted coating alloys on base steels and analyzing the elements diffused between them. The mechanism of infiltration process and the influence of temperature, medium and chemical compositions have been discussed. Finally, it has been shown that the infiltration is a macro manifestation of diffusion at the boundary face and a prerequisite to form firm metallurgical bond.

The SCC behavior of a high strength prestressing steel wire in saturated Ca(OH)_2+NaCl solutions and the effects of various factors including concentration of NaCl, potentials, pH values of solution and other additives were studied by cantilever beam test or slow strain rate test.The results showed that the presence of NaCl or Na_2SO_4 in saturate Ca(OH)_2 solution promoted SCC of the steel wire. The susceptibility to SCC increased with the increase of NaCl concentration and with the decrease of pH values of solution. The addition of NaNO_2 in solution effectively prevented the deleterious action of chloride ions,Based on the effect of potentials on SCC behavior of steel wire and the pH value of solution in an occluded cell which simulated the conditions of crack tip, it is thought that the SCC of prestressing steel wire in saturated Ca(OH)_2+NaCl solutions at free potential is mainly controlled by anodic dissolution mechanism. The effects of the spectrum of loading on threshold stress intensity factor are discussed in the light of the action of strain rate at the crack tip.

The corrosion behavior of YB45 steel (0.485%C; 0.59%Mn;0.28% Si;0.012% S and 0.02%P)in HC1 up to 12 N and the inhibiting effect of different concentrations of hexamethy-lenetetramine (U) and 2, 4, 6-trimethyl-pyridine (TMP) added singly and in combination to 8.7N HCl were studied by the classica potentiostatic polarization method at 25℃. For acid concentrations above 8.7N without inhibitors, the cathodic polarization curves nearly coincide so that corrosion rates increase less significantly with increasing acid concentrations. In 8.7N HCl,U is a strong cathodic inhibitor while TMP is far less efficient. When the two inhibitors are used in conjunction, only additive effect can be observed,but some impurities inTMP in appreciable amount will cause strong synergism.These phenomena are explained by saturated adsorption of H~+Cl~- "molecules" in concentrated HC1 and the further adsorption of U on H~+Cl~- layer at the Fe/solution interface.

The post-plating embri ttlement of Cd-Ti coated high strength steel 30CrMnSiNi2A in 3.5% NaCl solution has been studied. Notched specimens are used for tests. The stress vs time to fracture curves under potentiostatic polarization, the potentiodynamic cathodic polarization curve and the electrochemical hydrogen permeability have been measured under different aerated conditions. The phenomenon of the auto-acidification in artificial occluded cell and the characteristic fractography of the notched specimens have been observed and analyzed. The reason for post-plating embrittlement of Cd-Ti coated high strength steel and the way to avoid such embrittlement have been suggested.

Cyclic oxidation resistance of four home-made superalloys (211, 208, GH-37 and M-38) has been investigated at 900, 950, 1000, 1050 and 1100℃.Specimens were subjected to 200 thermal cycles, each of which consists of 1 hr heating followed by 10 min air cooling. Thermogravimetric measurements at lower temperatures showed linear weight gain with time. However, at temperatures above 1000℃ , weight loss following a short period of initial weight gain was observed due to severe spallation of the oxide scales. The logarithm of the amount of spallation increases linearly with oxidation temperature. Metallographic examination reveals the formation of the zone of depletion in certain alloying elements (Cr, Al, etc,). In the case of M-38 and GH-37 linear relationship between the logarithm of depth of the depletion zone and temperature was found.

Passive films on SUS36 stainless steel formed in vinylon formalin condensation with. Na_2MoO_4 and polarized under various potentials have been studied with the aid of X-ray photoelcctron spectra. It has been found that the corrosion resistance of passive film formed in anodic transpassive potential region (1020mV) is, much better than those formed in other anodic passive potentials (<950mV).

The properties of KCl-Ag/AgCl reference microelectrode, chloride ion selective microelectrode and tungesten microelectrode have been investigated. Preliminary results show that reference microelectrode has a stable potential with a small coefficient of temperature. In the absence of other halide (?)ons, the potential of ehloride ion selective microelectrode bears a linear relationship with logac(?) The change in the solution acidity and the presence of other ions have less effect on the linear relationship. Under acid conditions, the tungesten mjcroelectrode in NaCl or MgCl_2 solution have a stable potential which is quite linear with the pH value of the solution and is independent of the solution concentration. Other (?)ons existing in the solution in low concentration, do not affect the linear relationship. Some results have been obtained when the microeiectrodes in crevice corrosion and stress corrosion cracking studies and agreed well with the results obtained by other methods.