The microstructure and tensile property of 2297-T87 Al-Li alloy in the 1/2 thickness layer were investigated by optical microscopy,scanning electron microscopy,transmission electron microscopy and tensile tests.The results show that the tensile property of 2297-T87 Al-Li alloy in different directions in the same thickness layer have obviously anisotropic.The tensile strength law is LT direction >L direction >45° direction >ST direction,the elongation law is L direction >45°direction >LT direction >ST direction.L direction,LT direction and 45° direction are mixed fracture dominated by plastic fracture,while brittle fracture is dominant in ST direction.The main precipitated phases in the crystal are lath T1 phase and acicular θ'phase.The number of T1 phase is significantly higher than θ'phase,which is the main strengthening phase of 2297 alloy.

Using the mixed powder of cast tungsten carbide with different eutectic microstructure content and nickel-based alloy as raw material,the welding layers were prepared by plasma transfer arc (PTA)surfacing.Microstructure and wear resistance of each welding layer were studied by optical microscope,scanning electron microscope and G65 abrasive wear test.The results show that the cast tungsten carbide with high eutectic structure can improve the microstructure of the welding layer,which has the characteristics of uniform distribution of hard phases,no holes and high hardness.At the same time,the wear resistance of the obtained welding layer is improved remarkably.

Ultra-fine WC powder contains a high surface energy in the developed suriace area,which exhibits a strong adsorption capacity for gases,liquids or particles,and is easily aggregated into secondary particles spontaneously,which leads to the sample using conventional laser particle size analysis method can not be effectively dispersed.The laser particle size distribution curve is always with a "trailing".In this paper,we ground the sample for 1 hour,then added the sample after grinding into the anhydrous ethanol,and into the external ultrasound machine for 10 minutes.Finally,the sample was tested.The particle size distribution curve of this test method is normal distribution,with good precision,and the relative standard deviation of laser particle size distribution characteristic value (d (10),d (50)and d (90))is less than 5%.

In order to improve the status quo that the commonly used cutter pick in coal mining engineering is easy to failure due to the damage of the carbide bit,the effects of TiC and TaC additives on the performance of WC-Co cemented carbide bit were studied.The results show that the structural hardness (HRA)of the treated bit can reach 87 ,which is much higher than the national standard of cutter pick of 65.Compared with the interior,the surface fracture toughness of the cutter pick is lower due to the formation of a large number of carbides on the surface,the average fracture toughness is about 15.50 MPa ·m^1/2.The internal fracture toughness is improved due to the presence of a large number of non-carbides,and its average value is 16.31 MPa ·m^1/2.

The friction and wear properties of binderless WC-based cemented carbide with different VC and TiC concentration were investigated.The experimental results show that the average friction coefficient and wear rate of cemented carbide decrease with the increase of VC and TiC content.The minimum wear rate of 4.6× 10^-5 mm^3/Nm is obtained when the mola concentration of VC and TiC are 5%,which is reduced by about 98% compares with that of cemented carbide without VC or TIC'.The wear resistance of cemented carbide is positively correlated with its hardness.The hardness of cemented carbide without or with low content of VC and TiC is lower,and its wear mechanism is mainly adhesive wear and abrasive wear,and the wear rate is higher.The hardness of cemented carbide with high VC and TiC content is higher,and its wear mechanism is mainly grain pullout and surface cracking,and the wear rate is lower.

Currently,spectrophotometry method and ICP-AES method are generally used to determine low content tungsten in ores .With the continuous development and innovation of analytical techniques,ICP- MS method has obvious advantages in the field of trace analysis.In this paper,ICP-MS as a new instrument analysis and detection method with the advantages of high-resolution,high sensitivity,low detection limit and rapid analysis is established to meet the requirements of rapid analysis of low content tungsten in tantalum-niobium ores in industrial production,which is superior to current analytical methods developed by industry standards.After testing,the analytical results of ICP-AES are accurate and reliable,and can be applied in practice.

The extraction of scandium from the leaching solution of tungsten residue was carried out by P204-TBP,sulfuric acid eluted the iron in the loaded organic phase and scandium was stripped in the eluted organic phase by sodium hydroxide.The results show that in the system of 5% P204+3% TBP+ kerosene, the extraction rate of scandium is 97.37% through five-stage counter current extraction with O/A ratio of 1∶10,temperature of 25 ℃,and time of 15min.Through five-stage counter current elution by 4 mol/L H2SO4,the elution rate of iron is 98.63%,while the scandium loss rate is less than 1%.The eluted organic phase was stripped with 3mol/L sodium hydroxide.The single-stage stripping rate of scandium reaches 98.31%.By using the method,the purity of crude scandium can reach more than 82%,and the total recovery rate of scandium is more than 95%.

Advanced aliphatic amine extractant are widely used in the metallurgical industry.This paper focuses on several commonly used advanced aliphatic amine extractant and its application in the rare metals solvent extraction process.

TiH2powder with a particle size of less than 74μm and a density of 1.27g/cm^3 was obtained by hydrogenation of pure Ti waste,and then TiH2powder was treated by pretreatment,cold isostatic pressing and high temperature sintering process to produce pure Ti.The strength and density of the compact were tested by three-point bending tester and drainage method.The change trend of the strength and density of the compact,the density of the sintered sample,and the chemical composition and microstructure of the compact were studied by the means of SEM,EDS and the hydrogen/oxygen element analysis.The results show that the TiH2 powder pretreated at 500℃ can obtain higher compact strength and density under the molding pressure of 200MPa.Pure Ti sintered samples with equiaxed structure,density of 4.48g/cm^3 and hydrogen content of 0.001% were prepared from TiH2compacts with vacuum degree higher than 10-3 Pa, calcination temperature of 1400℃,calcination time of 2h.The other chemical compositions of pure Ti sintered samples met the national standard of pure Ti.

The mechanism of synergistic solvent extraction of nickel by P204 and 4PC from acidic sulfate solution was studied with slope method,constant molecale method and saturation extraction method,respectively. The thermodynamic equilibrium constant of the synergistic reaction was determined,and its enthalpy and entropy changes were also obtained.The results show that the combination of P204 with 4PC has a positive synergistic effect for nickel extraction,and the extracted complex is identified as NiA2L2.The synergistic solvent extraction is an endothermic reaction with enthalpy change of 29.52J/mol and entropy change of-6.53kJ/(mol·K).The synergistic solvent extraction system of P204and 4PC can obviously promote the selective extraction of nickel from acidic sulfate solution.