The influences of cystine on the electroless nickel deposition rate, hydrogen evolution, reactive activation energy, anodic oxidation of H2PO and cathodic reduction of Ni2+ were studied. The elemental composition of the deposit and the valence state of sulfur were also determined. The acceleration mechanism of cystine could be attributed to the adsorption and interaction of cystine and H2P on the active metal surface. In result, the cleavage of P-H bond of H2PO was accelerated and the electrons were much easily transported to metal surfaCe though atom S in cystine and atom H. Thus the reductions of Ni2+,H+ and H2PO on the metal surface were accelerated simultaneously.

The role of boron in inhibiting dezincification of aluminium brass was investigated by ICP, XRD,EMPA and PAT methods. By adding trace boron into aluminium brass with or without arsenic, the resistance of the brass against this type of selective corrosion could be remarkably improved. Due to the synergetic effect of boron and arsenic, dezincification was hindered. The optimum content of boron in the alloy was about 0.01% in the absence of arsenic, and 0.005~0.008% in the presence of arsenic.For aluminium brass without boron and arsenic, dezincification was attributed to the diction of grain boundary because of its large grain size. For aluminium brass with boron but without arsenic, boron could move into the grain boundary and divacancy, wich were considered to be the route of dezincification, and then reduced the dezincification rate. In the presence of boron and arsenic in brass, boron and arsenic atoms moved into the divacancy, blocked the way of dezincification, so that dezincification could not take place.

The inhibition effect of piperidine (PD) for pitting initiation and propagation of AISI 304 stainless steel in NaCl solution of various concentrations was investigated by potentiodynamic anodic polarization and P-G transient inhibition measurements. In order to evaluate the long-term inhibition performance of PD, the pitting breakdown potentials of the system, 304 SS/0.5 mol/L NaCl + 5 mmol/L PD, were measured continuously for 1100 hours. The results showed that the pitting propagation was inhibited to a certain extent. The possible inhibition mechanism of PD for pitting initiation and propagation was discussed according to the competitive adsorption theory. In addition, a new idea of "Critical Ratio" of PD concentration to Cl- concentration was suggested for the judgement of inhibition effect. For the system in which the ratio of PD concentration to Cl- concentration was greater than the "Critical Ration", the inhibition role was more satisfactory than that in which the ratio is less than the criterion. The anodic desorption of the inhibitor was discussed preliminarily.

A kinetic model describing the interaction between inhibitor adsorption/ desorption and anodic processes of metals was proposed on the basis of the previous serial studies. The changes in inhibitor coverage with potential and inhibitor concentration, the meaning of desorption potential and half coverage potential,the current transient response to the disturbance of potential and concentration, as well as steady-state anodic polarization curves were examined according to the proposed model.

The oxidation of two Fe-Nb alloys containing 15 and 30 wt% Nb respectively was studied at 600~800℃finder low oxygen pressures, similar to the environments prevailing in coal gasification. The main reaction was internal oxidation of niobium with the formation of niobium oxides (NbO2 and Nb2O5) and in some cases of a double Fe-Nb oxide. The kinetics of this reaction was very slow at 600℃ but rather fast at 700and 800℃. A peculiar feature of the internal oxidation of these alloys was that the distribution of the internal oxides was the same as that of the Nb-rich phase in the original two-phase alloys. This behavior and the lack of formation of external scales of niobium oxides were mainly the result of the limited solubility of niobium in iron and of the consequent. presence of two phases in the alloys under examination.

Anodic polarhation curves of iron in (0.01~1 mol/L) NaHCO3 solution were measured using potentiodynamic method in the presence or absence of 0.4T magnetic field. It was shown that iron in these solution exhibited act ive-passive-transpassive characteristics. Three types of polarization curves obtaniedcould be explained thermodynamically on the assumption that the variation of NaHCO3 concentration caused different electrochemical reactions occurring on iron. Imposed magnetic field did not change the electrochemical reaction mechanism but would increase current density at the given potential. Interaction between the effect of magnetic field and the effect of passive film resulted in different efficiency of magnetic field in different concentrations of NaHCO3 solutions.

A decorative passive film containing Cr was obtained by passiVating Fe-W amorphous deposits in a chromate solution. Anodic polarization curves showed that the pitting potential of the passivated Fe-W deposit was high up to 1.78V in 3wt% NaCl solution at 25℃ and that the passiVation treatment improved its corrosion resistance against Cl- attack. The results of AES and XPS analyses revealed that the passive film consisted of two layers. The outer layer was a mixturof Fe(CrO4 ) 3· Cr2 (CrO4 ) 3· Cr2 (Cr2 O7) 3·Fe (OH) 3 /FeOOH· WO3·nH2O and t he inner layer was a mixture of Cr2O3,CrO3 , CrOOH, FeO, Fe2O3and WO3. The thickness of the passive film was about 60nm.

Electrochemlcal impedance spectroscopy(EIS) technique、 applied to Investigate the electrochemical behaviour and corroslon characteristics ofaluminium ofindustrially pure grade In 3. 5% NaCI solution. The results showed that the appearance ofa capacltlve loop at lower anodic potentials was the feature of the system under study When the polarization potential E was more noble than-0．8V(vs. SCE),the passl、 films on the aluminium surface would be locally destroyed, and an Inductl、 loopcould beobtained at lower frequencies on the impedance spectra. The anti-corrosion performance and mechanism were discussed on the basis of the analysis on the EIS data measured at anodlc polarization.

Alternating current etching is an important technique for increasing the specific surface area of aluminium capacitor foil for low voltage use. The present research was carried out on the influence of etchant bath composition and operating parameters to obtain a desirable surface morphology and high capacitance of the etched foil while keeping its tensile strength within the required range. Experimental results showed that the etched foil with the largest capacitance up to 33 μF/cm2 could be obtained at a temperature of 47±2℃ and current density of 0.5A/cm2 in a hydrochloric acid etching solution containing a proper surface protectant and another auxiliary additive with the Al3+ concentration from 5.36 to 6.55g/L. Cyclic voltammetric curves were measured to explain the mechanism and effects of above-mentioned factors on AC etching.

An apparatus which could provide a low oxygen pressure was developed. The unit worked on the basis of an oxygen concentration cell (-)Pt, O2(P)

Cr-P alloys were deposited from the bath for chormium (Ⅲ) electrodeposition containing NaH2PO2.The effects of some electroplating parameters on P content in the obtained deposits were evaluated. The P content increased with decreasing cathodic current density and with increasing H2PO concentration in the bath. Tile anodic polarization behavior of the deposits in 0.5 mol/L H2SO4 and 1 mol/L HCl was examined. When tile P content exceeded 5 wt%, the deposited alloy exhibited excellent corrosion resistance and the passive current density was only 10-50μA/cm2.

The effect of electroless plated NiCoB alloy in the presence of electromagnetic field on the oxidation resistance of sythetic diamond was investigated by DTA, TGA, XRD and SEM. The results showed that a uniform and compact NiCoB coating could be formed on diamond surface by the technique.The coating raised the oxidation starting temperature of the diamond, therefore its resistance to oxidation was notably improved and the strength loss after oxidation at 900~10000170 was reduced.

To diminish the influence of concentration polarization and obtain correct kinetic parameters, a rotating disk electrode was used to study anodic dissolution of mild steel in acidic chloride media. Experimental r6Sults showed that anodic dissolution of mild steel was affected by pH with the Tafel slope ba varying from 91mV to 40mV as pH challged from 0.70 to 2.72. Chloride concentrations ranging from 0.1mol/L to 1.5 mol/L in this system did not influence the reaction. Anodic dissolution mechanism with two-electron transfer was suggested and a kinetic expression ia = 2FKa[OH-]e was deduced.

A series of dots on galvanostatic charge curve with equal time interval were chosen to form a time array t(i) and a corresponding overpotential array E(i). By assigning a possible static overpotential E and letting y(i) = E- E(i), another array Y(i) could be obtained. By letting W(i) = ln[Y(i +1)·y(i-1)-Y2(i)], an additonal array W(i) could generated. It could be proved that W(i) was linear with t(i). Moreover, with its slope Kand intercept B, the real static overpotential E∞ could be calculated. Furthemore, owing to the linear relationship between In[E∞-E(i)] and t(i), the parameters R1,Rp and Cd could be calculated through its slope K' and B'.