The effect of low-speed wire cut electrical discharge machining （WEDM-LS） on the bending strength of Ti（C,N）-based cermet of Ti（C,N）-7%WC -20%Ni-7%Mo was studied by hydraulic universal testing machine. The morphology and chemical composition of the machining surface, and the microstruc- ture of the deterioration layer were observed and analyzed by SEM and EDS. The results show that WEDM -LS causes obvious electrical erosion deterioration layer, significantly reducing the bending strength and increasing the intensity dispersion of the sample. There are a large number of microscopic defects such as micro-cracks,holes and grain shedding in microstructure of the deterioration layer.

The study was carried out on the effect of extrusion temperature on microstructure and properties of beryllium material and its texture evolution during extrusion. The results show that the crystal grains of beryllium ingot are refined after extrusion, and its tensile strength, yield strength and fracture elongation are improved in different degrees. With extrusion temperature increasing, beryllium grain size increases and （1010） fiber texture is enhanced, both affecting the mechanical properties of beryllium rods. In order to ana- lyze the relationship between mechanical properties, crystal structure and texture of extruded beryllium rods, mechanical testing was carried out with the samples obtained according to a certain slope angle along the extrusion direction. It is found that the tensile strength and yield strength significantly decrease, while the fracture elongation greatly increases. Therefore, the plasticity of beryllium material can be improved by controlling texture direction via equal channel extrusion.

The strain rate tensile tests of isostatie beryllium were carried out with the universal testing ma- chine at room temperature. The fracture and plastic deformation behavior of beryllium were investigated by using SEM and EBSD techniques. The results show that with the increase of strain rate, the strength of beryllium is increased, but the ductility is decreased and the stress intensity factor of beryllium material is also decreased. In addition, during the stretching process, the slip is the main mechanism of plastic deform- ation. The twin crystals have no obvious effect on plastic deformation for the isotropic effect of mechanical properties of isostatic beryllium,and have little contribution to the plasticity of beryllium.

Ni-Co/ZrO2 composite coatings were prepared by ultrasound-assisted electroplating in the system of sulfamate bath. The effects of current density, concentration of ZrO2 particles and ultrasonic power on hardness of Ni-Co/ZrO2 composite coatings were investigated with single variable method. The process pa- rameters of Ni-Co/ZrO2 composite electrodeposition were optimized. The coatings were tested by nanoin- dentation,and the morphology and composition of the optimized composite coatings were characterized by field emission scanning electron microscopy. The research results show that the optimized technological conditions are as follows：cathode current density of 5 A/dm2 , ZrO2 particle concentration of 10 g/L, ultrasonic power of 240 W. Under these conditions, the nanohardness, elastic modulus and the ratio of nanohardness to elastic modulus are up to 6.13 Gpa,291 Gpa and 0. 021 ,respectively. Furthermore,the coating is flat and compact,and ZrO2 nanoparticles are well eomposited in metal matrix.

High-purity platinum was prepared by the combination process of dissolution of crude platinum with aqua regia-oxidation and carrier hydrolysis-ion exchange-NH4 Cl precipitation,and the effects of impu- rity elements removal in each process step were studied. The experimental results show that platinum can be effectively separated from other precious metals and base metals by dissolution of crude platinum with aqua regia, and then oxidation and carrier hydrolysis,ion exchange and precipitation of Pt-containing solution. The obtained purified （NH4）2 PtCl6 precursor was calcined and washed,and Pt powder was prepared. Based on GDMS analysis,the impurity content in Pt powder is less than 3 ×10^-6 ,and the purity of platinum is more than 99. 999%.

The research progress of refractory high-entropy alloy is reviewed. The phase composition and crystal structure of refractory high-entropy alloy are analyzed. The performance advantages of refractory high-entropy alloy are introduced,including high temperature stability, strength and hardness and so on. The problems of high-entropy alloy are discussed in the three aspects of mass density, room temperature brittleness and high temperature oxidation resistance. Finally, the future development direction of the refractory high-entropy alloy is pointed out.

To study the influence of TiAlN coating on zinc melting recovery of waste coated cemented carbides,waste TiAlN-coated WC-Co cemented carbide was recycled by zinc melting at 880 ℃. The failure of the TiAIN coating during zinc melting recovery was analyzed , and the interaction among Zn,TiAlN coating and the substrate was also discussed as well as the existence form of TiAlN coating in the recycled WC powders. The results demonstrate that because of the barrier effect of the coating, uncoated cemented carbide scrap only needs 6 h insulation to be basically melted and loosened during zinc melting recovery,while TiAlN-coated WC-Co cemented carbide scrap needs 9 h. Dissolution and diffusion are not the main reasons for the failure of coatings. Molten zinc goes into the cemented carbide mainly through cracks to react with Co. The stress caused by the different thermal expansion coefficients of the coating and the substrate is the main reason for the formation and extension of the alloy surface cracks. The coating elements and flaky TiAlN coating are found still in the recycled WC powders based on EDS analysis.

The influences were researched of Cr content on the mechanical properties and corrosion resistance of WC-9（Coq-Ni） cemented carbide containing Mo. The results show that with the increase of Cr content,the density slowly decreases, while both the flexural strength and hardness increase firstly and then decrease. When Cr content is 0.6% ,alloy flexural strength reaches 2 845 MPa, HRA hardness achieves 91.2,and the density is 14.39 g/cm^3. Dipped in 2 mol/L H2SO4 ,HNO3 or HCI acid for 11 days,the alloy of 0.6 G Cr has the minimum corrosion rate and the best corrosion resistance. The alloy of 0.6 % Cr has no corrosion layer after soaking in low concentration HC1 solution （pH=3） for 90 days.

The chromium nitrate precipitation method was used to deeply remove phosphorus from ammonium tungstate solution.The effects on phosphorus removal were systematically investigated of chromium nitrate addition,reaction temperature,reaction time,ammonium tungstate solution pH and initial phosphorus concentration.The results show that under the optimal conditions of the chrome addition of 3 times the theoretical quantity,temperature of 55 ℃,time of 120 min,ammonium tungstate solution pH of 9.81 and initial phosphorus concentration of 37.4 mg/L,the residual phosphorus concentration in ammonium tungstate solution after phosphorus removal is 14.95 g/L,which meets the requirement for preparation of APT-0 grade products.

In view of low efficiency of rare earth recovery from rare earth molten salt electrolysis slag in fluoride salt system,a novel technology of roasting with sodium hydroxide-selective leaching with hydrochloric acid was proposed.The effects were systematically investigated of roasting temperature,roasting time,sodium hydroxide dosage,hydrochloric acid concentration,liquid-solid ratio,leaching temperature and leaching time on rare earth recovery from the slag.The leaching rate of rare earth is as high as 99.22% under the following conditions：roasting temperature of 600 ℃,roasting time of 1.5 h,the mass ratio of sodium hydroxide to the slag of 0.8∶1,hydrochloric acid concentration of 2 mol/L,liquid to solid ratio of 8∶1,leaching temperature of 40 ℃ and leaching time of 15 min.