WC-8 Co cemented carbide with different TiC contents was prepared by spark plasma sintering technology.The effects of TiC content on the relative density,mechanical properties and microstructure of WC-8 Co cemented carbide were analyzed.The experimental results show that with the increase of TiC content,the comprehensive properties of WC-8 Co cemented carbide increase firstly and then decrease at room temperature.WC-8 Co cemented carbide with 5%(mass fraction) TiC has better comprehensive mechanical properties.When the sintering temperature and pressure are 1 250 ℃ and 50 MPa,density,Vickers hardness,fracture toughness and flexural strength at room temperature of WC-5 TiC-8 Co cemented carbide are 98.85%,19.49 GPa,9.46 MPa·m1/2 and 1 893 MPa,respectively.The analysis results of cemented carbide densification sintering curve and microstructure morphology show that with the increase of TiC content,the starting temperature for sintering densification of the cemented carbide shifts to a lower temperature,resulting in the fluidity of Co phase deteriorating and the densification sintering condition worsening.The pores in the samples increase,leading to the decrease of Vickers hardness and mechanical properties of cemented carbide.

YG10 X submicro-grained cemented carbide anvils with large-scale size above ?160 mm were prepared by compacting,dewaxing,vacuum sintering and hot isostatic pressing(HIP) treatment,using ultrafine-grained WC-Co spray-dried mixed powders as starting materials.The effects of the matched process of vacuum sintering with HIP treatment and different dewaxing atmosphere on properties and microstructure of the anvils were investigated.The ?188 mm anvil prepared by 200~300 ℃×40 h slow hydrogen continuous dewaxing and matched sintering process supplemented by 1 380 ℃ hot isostatic pressing has uniform microstructure,fine grains and stable performance,its transverse fracture strength of each part is higher than 4 100 MPa,and average service life is longer than 9 000~11 500 times.

Medium-free dry grinding of medium-grain tungsten carbide powders was carried out using cemented carbide grinding bodies with different specifications and shapes.The ground tungsten carbide powders were analyzed by X-ray diffractometer(XRD),scanning electron microscope(SEM) and laser particle size analyzer.The powder size,subcrystal size,strain and laser particle size distribution of each group of ground tungsten carbide samples were compared,and SEM morphology of some samples was analyzed.The effects of shape and specification of grinding body and grinding time on the properties and grinding efficiency of tungsten carbide powders were discussed.The results show that cemented carbide rods have better grinding efficiency than cemented carbide balls.For the grinding body with the same type,the smaller the size,the better the grinding efficiency.With the extension of grinding time and the enhancement of grinding efficiency,both the average particle size and subgrain size of tungsten carbide powders decrease,the strain increases,and the particle size distribution is more concentrated.

2019年末,一场“不明原因”肺炎袭击湖北武汉,其由一种新型冠状病毒导致,来势汹汹。随后,国内多地发生新型冠状病毒感染的肺炎疫情。为抗击新型肺炎,各级政府及其部门、医疗工作者、企业以及普通民众皆全力以赴,用行动诠释了爱与责任。目前,国内已经实质性地控制住了新冠肺炎疫情。

Nd2O3 was recovered from the sintered Nd-Fe-B waste with the sulphate double salt precipitation method,the secondary oxalate precipitation method and the phosphate precipitation method.The industrially produced Nd-Fe-B waste was pretreated with sulfuric acid or oxalic acid.After alkalization and acid dissolution,neodymium ions were separated from iron by precipitation with oxalic acid or ammonium carbonate,and finally the crude Nd2O3 product was obtained by calcination.The morphology of Nd2O3 powder was observed by scanning electron microscope,and the purity of Nd2O3 product was determined by EDTA titration and the recovery rate was calculated.The purity and recovery rate of crude Nd2O3 products prepared with different methods are quite different.The purity of Nd2O3 is 74%~92%,the total recovery rate is 24%~29%,and the particle size is 3~200μm.These Nd2O3 products are of irregular shape and relatively high dispersity,and they are multihole and mostly fluffy.Considering the complexity of the process and the purity and recovery rate of Nd2O3,the sulfate double salt precipitation method has advantages in the practical application of Nd2O3 recovery from sintered Nd-Fe-B waste.

Vanadium was separated and recovered from titanium dioxide wastewater by solvent extraction using P507 as the extractor.The effects of extractor type and concentration,O/A phase ratio,solution pH,extraction temperature and time on the extraction rate of vanadium in titanium dioxide wastewater were investigated.The results show that the extraction rate of vanadium is more than 98% under the following conditions:organic phase of 15%P507+5%2-octyl alcohol+80% sulfonated kerosene,solution pH value of 2.0,O/A phase ratio of 1.25∶1,extraction temperature and time of 50℃ and 6min.The V2O5 product with a purity greater than 99% is obtained by sulfuric acid reverse extraction of the saturated organic phase,NaClO3 oxidation,ammonium salt precipitation and roasting at 540℃.

Using the leaching residue from acid treatment of spent automobile exhaust gas purifier catalysts as the adsorbent,the heavy metals Cu^2+and Cd^2+in the wastewater simulation solution were separated,and the effects of temperature,pH,adsorbent amount and adsorption time on the adsorption rates of Cu^2+and Cd^2+were investigated.The optimal adsorption conditions were obtained:temperature of 50℃,pH of 5.5,adsorbent amount of 0.5g and adsorption time of 1h.Under the optimal conditions,the adsorption rates of Cu^2+and Cd^2+in 20mg/L solution are 99.95%and 99.22%,and the saturated adsorption capacities of Cu^2+and Cd^2+in 1g/L solution are 99.61mg/g and 42.17mg/g,respectively.The adsorption of Cu^2+and Cd^2+by the leaching residue conforms to the second-order kinetic model,and chemical adsorption is the dominant adsorption mode.

In order to explore the effect of the combined action of Ce and La in natural bastnaesite on denitration performance,the CexLa1-x active component was prepared by microwave heating and loaded onγ-Al2O3 for activity test.Ce0.8La0.2 catalyst has the best denitration effect and 78%NO conversion at 350℃.The results of BET,NH3-TPD,XRD,Raman and XPS show that the active component of Ce0.8La0.2 catalyst is a solid solution containing Ce and La,which has better adsorption capacity of NH3 and higher specific surface area,and the surface adsorption of oxygen on Ce0.8La0.2 catalyst is one of the reasons for improving the catalytic performance of NH3-SCR.

La-Fe-B alloys prepared by arc melting were analyzed by X-ray powder diffractometer,scanning electron microscope,energy spectrometer and differential thermal analyzer,to obtain their phase composition,microstructure and phase transition process.The experimental results show that the solidification microstructure of the alloys is composed ofα-Fe andα-La phases.With the increase of rare earth La content,the content ofα-Fe phase obviously decreases,and the formation temperature of La2Fe14B phase decreases.The solidification phase transition process of the alloys was simulated by using phase diagram calculation technique and Scheil model.The simulated results are in good agreement with experimental results.