Reduction kinetics of Ni_3S_2 was experimen- tally studied by following the time required for completion of the hydrogen reduction reaction in the presence of calcium oxide.A simple empirical integration equation,deri...Reduction kinetics of Ni_3S_2 was experimen- tally studied by following the time required for completion of the hydrogen reduction reaction in the presence of calcium oxide.A simple empirical integration equation,derived for describing the ef- fect of CaO/S molar ratio,temperature,hydrogen concentration and the average diameter of Ni_3S_2 grains,may be shown as following: t|_(X=1)=2.317×10^(-6)d_(Ni_3S_2) C_(H_2)^(-1) β^(-2.29)e^(13710/T),min The reduction reaction is of first order with respect to hydrogen concentration,and the apparent reac- tion activation energy is 114.0 kJ/mol.A great ma- jority of metallic Ni reduced from Ni_3S_2 is distrib- uted in the products evenly.展开更多
The dynamic corrosion process of bio-oxidation of copper-nickel sulfide from Karatungk in northern Xinjiang Province of China was studied. The polished wafer of the copper-nickel sulphide was used to carry on a series...The dynamic corrosion process of bio-oxidation of copper-nickel sulfide from Karatungk in northern Xinjiang Province of China was studied. The polished wafer of the copper-nickel sulphide was used to carry on a series of oxidation corrosion experiment by Acidithiobacillus ferrooxidans. The changes of superficial corrosion appearance and the mineral dynamic corrosion process were discovered by microscope observation. Then,the galvanic cell model was established,and the bio-oxidation activation order of typical copper-nickel sulphide minerals was ascertained as pyrrhotite>pentlandite>chalocopyrite.展开更多
The effect of sulphide(Na2S)concentration(SC)on the corrosion and cavitation erosion behaviours of a cast nickel aluminium bronze(NAB)in 3.5% NaCl solution is investigated in this study.The results show that when the ...The effect of sulphide(Na2S)concentration(SC)on the corrosion and cavitation erosion behaviours of a cast nickel aluminium bronze(NAB)in 3.5% NaCl solution is investigated in this study.The results show that when the SC exceeds 50 ppm,the hydrogen evolution reaction dominates the cathodic process,and a limiting current region appears in the anodic branch of the polarisation curve due to the formation of a copper sulphide film,which is a diffusion-controlled process.After longterm immersion,the increased mass loss rate of NAB with the sulphide additions of 20 and 50 ppm is attributed to the less protective films,which contains a mixture of copper oxides and sulphides.Moreover,NAB undergoes severe localised corrosion(selective phase corrosion,SPC)at the β’phases and eutectoid microstructureα+κⅢ.By comparison,NAB undergoes general corrosion and a copper sulphide film is formed in 100 and 200 ppm sulphide solutions.Cavitation erosion greatly increases the corrosion rate of NAB in all solutions and causes a negative potential shift in 3.5%NaCl solution due to the film destruction.However,a positive potential shift occurs in the solutions with SC higher than 50 ppm due to the accelerated mass transfer of the cathodic process.The cavitation erosion mass loss rate of NAB increases with the increase of SC.The occurrence of severe SPC decreases the phase boundary cohesion and causes brittle fracture under the cavitation impact.The corrosion-enhanced erosion is the most predominant factor for the cavitation erosion damage when the SC exceeds 50 ppm.展开更多
文摘Reduction kinetics of Ni_3S_2 was experimen- tally studied by following the time required for completion of the hydrogen reduction reaction in the presence of calcium oxide.A simple empirical integration equation,derived for describing the ef- fect of CaO/S molar ratio,temperature,hydrogen concentration and the average diameter of Ni_3S_2 grains,may be shown as following: t|_(X=1)=2.317×10^(-6)d_(Ni_3S_2) C_(H_2)^(-1) β^(-2.29)e^(13710/T),min The reduction reaction is of first order with respect to hydrogen concentration,and the apparent reac- tion activation energy is 114.0 kJ/mol.A great ma- jority of metallic Ni reduced from Ni_3S_2 is distrib- uted in the products evenly.
基金Project(2006AA06Z127) supported by the National Hi-tech Research and Development Program of ChinaProjects(50674029, 50274024) supported by the National Natural Science Foundation of China+1 种基金Project(20060145015) supported by Doctoral Program Foundation of Ministry of Education of ChinaProject(20052030) supported by the Natural Science Foundation of Liaoning Province, China
文摘The dynamic corrosion process of bio-oxidation of copper-nickel sulfide from Karatungk in northern Xinjiang Province of China was studied. The polished wafer of the copper-nickel sulphide was used to carry on a series of oxidation corrosion experiment by Acidithiobacillus ferrooxidans. The changes of superficial corrosion appearance and the mineral dynamic corrosion process were discovered by microscope observation. Then,the galvanic cell model was established,and the bio-oxidation activation order of typical copper-nickel sulphide minerals was ascertained as pyrrhotite>pentlandite>chalocopyrite.
基金financially supported by the National Natural Science Foundation of China (Nos.51601058 and 51879089)the Fundamental Research Funds for the Central Universities of P.R.China (No.2018B59614)+1 种基金the Natural Science Foundation of Jiangsu Province (BK20191161),the Changzhou Sci & Tech Program (Grant No.CJ20180045)the first group of 2011 plan of China’s Jiangsu province (Grant No.[2013] 56) (Cooperative Innovational Center for Coastal Development & Protection)
文摘The effect of sulphide(Na2S)concentration(SC)on the corrosion and cavitation erosion behaviours of a cast nickel aluminium bronze(NAB)in 3.5% NaCl solution is investigated in this study.The results show that when the SC exceeds 50 ppm,the hydrogen evolution reaction dominates the cathodic process,and a limiting current region appears in the anodic branch of the polarisation curve due to the formation of a copper sulphide film,which is a diffusion-controlled process.After longterm immersion,the increased mass loss rate of NAB with the sulphide additions of 20 and 50 ppm is attributed to the less protective films,which contains a mixture of copper oxides and sulphides.Moreover,NAB undergoes severe localised corrosion(selective phase corrosion,SPC)at the β’phases and eutectoid microstructureα+κⅢ.By comparison,NAB undergoes general corrosion and a copper sulphide film is formed in 100 and 200 ppm sulphide solutions.Cavitation erosion greatly increases the corrosion rate of NAB in all solutions and causes a negative potential shift in 3.5%NaCl solution due to the film destruction.However,a positive potential shift occurs in the solutions with SC higher than 50 ppm due to the accelerated mass transfer of the cathodic process.The cavitation erosion mass loss rate of NAB increases with the increase of SC.The occurrence of severe SPC decreases the phase boundary cohesion and causes brittle fracture under the cavitation impact.The corrosion-enhanced erosion is the most predominant factor for the cavitation erosion damage when the SC exceeds 50 ppm.
