In order to expand the application of the electrodeposited Ni-Fe alloy foil,their mechanical and magnetic properties were studied after heat treatment.The development of grain growth during annealing was in-situ online investigated using a heating stage microscope,and the texture was analyzed via X-ray diffraction(XRD)and electron back-scattered diffraction(EBSD).The results indicated that abnormal grain growth usually occurred during annealing at 1000-1050°C.The{111}oriented grains preferentially grew as the annealing temperature and holding time increased.The plasticities of the electrodeposited Ni-Fe alloy foils after heat treatment were better than those of the original samples.The excellent ductility was obtained without a loss in magnetic properties after annealing at 1100°C for 6h.
The vanadium titano-magnetite(VTM)iron ore fines of 110-150μm in diameter were reduced in a transparent quartz fluidized bed by 70%CO-30%H2(volume fraction)mixtures.MgO powders served as coating agent to solve sticking problem.Two coating methods were introduced in this experiment:high temperature injection method and briquetting→oxidizing roast→crushing method.According to the experimental results,the minimum effective coating amount of MgO was 0.1mass%.The metallization ratio(MR)of the product rose from around 58% to above90% with the above treatments.To investigate the sticking mechanism of fine ore,the morphology evolution was investigated.Instead of iron whiskers,an interlaced fibrous porous surface formed.The ulvospinel(2FeO·TiO2)in VTM is more difficult to be reduced than FeO according to thermodynamic calculation.XRD results showed that MgO diffused into Fe2O3 lattice before forming pleonaste(MgO·Fe2O3)during oxidizing roast at 1 273 K.The melting point of the pleonaste is 1 986 Kand that made contribution to prevent the sticking problem.
Lei GUOJin-tao YUJing-kun TANGYin-he LINZhan-cheng GUOHui-qing TANG
