Deep cryogenic treating (DCT) was applied on Cu-14Fe and Cu-8Cr in-situ composites and its effects on mechanical property and electrical conductivity of the composites were investigated. For comparison, the effects of DCT on properties of the corresponding composites with 0.1%Ag alloying (i.e. Cu-14Fe-0.1Ag and Cu-8Cr-0.1Ag) were also investigated. The results showed that the ultimate tensile strengths of Cu-14Fe and Cu-8Cr were greatly raised by 106MPa and 56MPa after DCT, respectively, whereas those of the Cu-14Fe-0.1Ag and Cu-8Cr-0.1Ag remained unchanged. The increments of electrical conductivity in Cu-14Fe and Cu-8Cr were much higher than those in corresponding Cu-14Fe-0.1Ag and Cu-8Cr-0.1Ag. Before DCT, the electrical conductivities of Cu-14Fe and Cu-8Cr were lower than those of the Cu-14Fe-0.1Ag and Cu-8Cr-0.1Ag, respectively; whereas after DCT, the electrical conductivities of Cu-14Fe and Cu-8Cr were higher than those of the corresponding composites with 0.1%Ag micro-alloying. The possible mechanisms involved in the effects of DCT on the properties of composites were discussed in this paper
Passivator components of phytic acid, hydrogen peroxide, boric acid and polyethylene glycol was optimized by orthogonal experiment. Corrosion resistance of passivation film of brass-strip was invertigated by salt spraying, weight loss and electrochemical test. The results show that the optimization passivator consists of phytic acid (50% mass fraction) 8ml/L, hydrogen peroxide (mass fraction 30%) 30ml/L, boric acid 5g/L, polyethylene glycol 15ml/L and additive 4g/L. Corrosion current density and corrosion rate of the brass-strip specimens coated by rich-phytic acid passivator are similar to that treated by traditional sodium dichromate passivator, the characteristic of anti-tarnish slightly better than that coated by sodium dichromate passivator. The feature of rich-phytic acid passivator is environmental protection.
The dezincification corrosion resistance of complex aluminum-brass HAl72-2.5-1 was studied by weight-loss, metallographic analysis method and energy dispersive spectroscopy. The effect of processing states and Al content(2.0%、2.5%、3.0%)in brass on zinc corrosion resistant was investigated. The research result shows that corrosion resistant is affected greatly by processing state, as-cast organization is loose and with much beta phrase, the dezincification of beta phrase is easy in corrosion solution, corroded at 75°C in 1% CuCl2 solution for 30 days. The dezincification layer of as-cast brass is over 137.3μm. Compare with the as-cast alloy, the corrosion depth of brass plate hot-rolled is only about 70.6μm, because the recrystallization process and the β phase dissolved into α phase during hot rolling process, the construction is more condense than that in as-cast state. The corrosion goes easily along the grains orientation which occurs in cold rolling, and existence of residual stress accelerates stress corrosion, which turns higher corrosion rate than that hot-rolled brass. The corrosion velocity enhances with the increase of Al content in brass.
Aging treatment of Cu-17Fe alloy was investigated by a vacuum heat treating furnace in high magnetic furnace. The microstructures were documented using scanning electron microscopy (SEM). The solid solubility of Fe in Cu matrix was analysed by energy spectrometer (EDS). The mechanical properties were measured with a Vickers hardness tester. The electrical conductivity was measured with a micro-ohmmeter. The results showed that high magnetic field can promote spheroidization of the Fe dendrites, the spheroidization intensifies and the solid solubility decreases with the increasing magnetic induction intensity of the high magnetic field exerted to the alloy, the solid solubility of Fe is minimum when the magnetic induction intensity is 10T at 500°C during precipitation. And Cu-17Fe alloy has a good strength/conductivity combination of 110Hv/63%IACS after aging treatment of 10T at 500°C for 1h.
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