In order to effectively separate galena and jamesonite and improve the recovery during the mixing flotation, the interaction mechanisms between the minerals and the collector of diethyl dithiocarbamate （DDTC） were i...In order to effectively separate galena and jamesonite and improve the recovery during the mixing flotation, the interaction mechanisms between the minerals and the collector of diethyl dithiocarbamate （DDTC） were investigated. Single mineral flotation test was organized to research the effect of pulp pH value on the flotation behavior of galena and jamesonite. Electrochemistry property of the interaction of these two minerals with DDTC was investigated by cyclic voltammetry and Tafel tests. Flotation test shows that the recovery of jamesonite in high alkaline pulp is strongly depressed by lime （Ca（OH）2）. The cyclic voltammetry and Tafel tests results show that the interaction between galena and DDTC is an electrochemical process. High pH value has little influence on the interaction between galena and DDTC, while it has great effect on jamesonite due to self-oxidation and specific adsorption of OH^- and CaOH^＋ on jamesonite surface. Non-electroactive hydroxyl compound and low-electroconductive calcium compounds cover the surface of jamesonite, which impedes electron transfer and DDTC adsorption, thus leads to very low floatability of jamesonite.展开更多
The galvanic corrosion behavior of metal-matrix composite plain carbon steel/boron carbide （B4C） in 3.5% NaCl solution was studied. The composite was locally produced as a weld band on carbon steel by means of the g...The galvanic corrosion behavior of metal-matrix composite plain carbon steel/boron carbide （B4C） in 3.5% NaCl solution was studied. The composite was locally produced as a weld band on carbon steel by means of the gas tungsten arc welding process and using nickel as the wetting agent. Samples from the weld band, heat-affected zone and parent metal region were extracted precisely and DC/AC electrochemical tests in combination with techniques such as scanning electron microcopy and energy dispersive spectrometry were conducted. The results of the electrochemical tests show that the corrosion resistance of the parent metal sample is higher than that of the welded composite and the HAZ samples. However, as the corrosion potential （Eco^r） of the parent metal is more positive than other two samples, this becomes the cathode in galvanic couples with two other samples. On the other hand, the weld composite sample is also cathodic due to its more positive Ecorr compared to HAZ sample. This means that the HAZ can be particularly at risk of preferential dissolution. The approach can be used in specific areas on plain carbon steel to locally increase hardness and resistance to abrasion and reduce manufacturing costs.展开更多
The effects of trace element Fe on the corrosion behavior of AZ80 magnesium alloy were investigated by salt spray test and electrochemical measurements.The results show that the corrosion rate decreases with decreasin...The effects of trace element Fe on the corrosion behavior of AZ80 magnesium alloy were investigated by salt spray test and electrochemical measurements.The results show that the corrosion rate decreases with decreasing the trace element Fe content in an approximately linear relation even though the amount of trace element Fe reduces to 0.000 2%(mass fraction).The electrochemical measurements show that the corrosion potential(φcorr)of the alloy with lower trace element Fe content shifts to less negative value.It is suggested that the control trace element by purification is an effective way to enhance the corrosion resistance of AZ80 magnesium alloy.展开更多
基金Projects(5110417951374247)supported by the National Natural Science Foundation of China
文摘In order to effectively separate galena and jamesonite and improve the recovery during the mixing flotation, the interaction mechanisms between the minerals and the collector of diethyl dithiocarbamate （DDTC） were investigated. Single mineral flotation test was organized to research the effect of pulp pH value on the flotation behavior of galena and jamesonite. Electrochemistry property of the interaction of these two minerals with DDTC was investigated by cyclic voltammetry and Tafel tests. Flotation test shows that the recovery of jamesonite in high alkaline pulp is strongly depressed by lime （Ca（OH）2）. The cyclic voltammetry and Tafel tests results show that the interaction between galena and DDTC is an electrochemical process. High pH value has little influence on the interaction between galena and DDTC, while it has great effect on jamesonite due to self-oxidation and specific adsorption of OH^- and CaOH^＋ on jamesonite surface. Non-electroactive hydroxyl compound and low-electroconductive calcium compounds cover the surface of jamesonite, which impedes electron transfer and DDTC adsorption, thus leads to very low floatability of jamesonite.
文摘The galvanic corrosion behavior of metal-matrix composite plain carbon steel/boron carbide （B4C） in 3.5% NaCl solution was studied. The composite was locally produced as a weld band on carbon steel by means of the gas tungsten arc welding process and using nickel as the wetting agent. Samples from the weld band, heat-affected zone and parent metal region were extracted precisely and DC/AC electrochemical tests in combination with techniques such as scanning electron microcopy and energy dispersive spectrometry were conducted. The results of the electrochemical tests show that the corrosion resistance of the parent metal sample is higher than that of the welded composite and the HAZ samples. However, as the corrosion potential （Eco^r） of the parent metal is more positive than other two samples, this becomes the cathode in galvanic couples with two other samples. On the other hand, the weld composite sample is also cathodic due to its more positive Ecorr compared to HAZ sample. This means that the HAZ can be particularly at risk of preferential dissolution. The approach can be used in specific areas on plain carbon steel to locally increase hardness and resistance to abrasion and reduce manufacturing costs.
基金Project(2007CB613705)supported by the National Basic Research Program of China
文摘The effects of trace element Fe on the corrosion behavior of AZ80 magnesium alloy were investigated by salt spray test and electrochemical measurements.The results show that the corrosion rate decreases with decreasing the trace element Fe content in an approximately linear relation even though the amount of trace element Fe reduces to 0.000 2%(mass fraction).The electrochemical measurements show that the corrosion potential(φcorr)of the alloy with lower trace element Fe content shifts to less negative value.It is suggested that the control trace element by purification is an effective way to enhance the corrosion resistance of AZ80 magnesium alloy.
