Nickel-based tungsten carbide（Ni60-WC）was coated on 40 Cr substrate by oxygen-acetylene flame spraying,and then the coating was subjected to electrical contact strengthening.Microstructure of coating section was observed by metallographic microscope before and after electrical contact strengthening,microhardness distribution of coating section was analyzed by microhardness tester,and tungsten element distribution of coating and substrate was analyzed by SEM surface scan.The results indicate that electrical contact strengthening can significantly improve the coating quality and hardness,and result in metallurgical bonding between coating and substrate.

TiO2and CdS-TiO2 photocatalysts were prepared with sol-gel method,and they were characterized by X-ray diffraction（XRD）,scanning electron microscope（SEM）and UV-Vis absorption spectroscopy.The results indicate that TiO2 is anatase and CdS is hexagonal after 500℃ vacuum treatment.CdS-TiO2 has the smallest particles with CdS doping amount of 5% molar fraction.Cd and S atomic ratio approaches1∶1.And CdS doping results in red shift of the absorption edge of TiO2.With the increase of doping amount of CdS,photocurrent of CdS-TiO2 is enhanced firstly and then weakened,and 5% CdS-TiO2 has the highest photocurrent of 1.2mA/cm^2.The results of degradation experiments of methylene blue in visible light show that with the increase of CdS doping amount,the degradation rate of methylene blue increases gradually by CdS-TiO2.The highest degradation rate of methylene blue is 57%,which is attributed to5% CdS-TiO2.

La0.94Mg0.06Ni3.49Co0.73Mn0.12Al0.20 hydrogen storage alloy was modified by polyaniline addition and chemical deposition of polyaniline.The results of XRD and SEM show that phase composition of the modified alloy is unchanged by either polyaniline addition or chemical deposition of polyaniline.Coral-like polyaniline was coated on the surface of the modified alloy by polyaniline addition,and the surface is coarser of the modified alloy by chemical deposition of polyaniline.After modification by polyaniline addition,the maximum discharge specific capacity of the alloy electrode is improved from 346.4mA·h/g to 354.8mA·h/g,and its capacity retention rate after 50 cycles increases from 69.5%to 73.0%.After modification by chemical deposition of polyaniline,the maximum discharge specific capacity of the alloy electrode decreases to 307.8mA·h/g,but its capacity retention rate increases to 82.6%.The results of kinetic tests show that the kinetic properties of the alloy are improved after modification by polyaniline addition and decreased with stronger corrosion resistance after modification by chemical deposition of polyaniline.Thus,it is very important to select a suitable polyaniline modification method.

Al-Sc master alloys with 0.85%～4.20% scandium content were prepared by aluminothermic reduction of Sc2O3 in NaF-NaCl-KCl-ScF3 molten salt system.Intermetallic Al3 Sc was introduced as a product of Sc2O3 aluminothermic reduction reaction for thermodynamic calculation,and the results reveal that the reaction can spontaneously proceed at 1 013 K～1 173 Kand it is exothermic.Isothermal saturation methods were employed to study the solubility of Sc2O3 in NaF-NaCl-KCl molten salt system.The results show that the solubility of Sc2O3 can be improved by increasing the temperature and NaF content or adding ScF3.Adding ScF3 has the most significant effect.The effects were investigated of temperature and ScF3 addition on Sc recovery during aluminothermic reduction.The results show that Sc recovery increases firstly and then decreases with increased temperature or addition of ScF3,and reaches the maximum at 1 133 Kor with 3% ScF3 addition.The climax of Sc recovery rate is up to 86.06% obtained under the conditions of 3%ScF3addition,1 133 Kand 1.5hisothermal period.The prepared Al-Sc master alloys were analyzed by SEM and EDS.The results demonstrate that there are Al3Sc particles in Al-Sc master alloys,showing square or polygonal shape with small size and dispersed in the matrix.

Compared with chromium doping in solid phase,WC powder prepared with Cr-doped ammonium paratungstate（APT）crystal has better macroscopic and microscopic uniformity.And ultrafine WC-Co cemented carbide prepared with the above WC powder has fine grains,narrow particle size distribution and uniform microstructure,there are no abnormal grain and porosity defects in the alloy,and its hardness and strength are improved to a certain extent with similar density,cobalt magnetism and magnetic force.

The compacts of YG6X、YG6and YG20 C mixture materials were presintered in vacuum at 900℃.The effect of placement time in the air of the presintered compacts on the properties of cemented carbides was studied by using physical property tests and metallographic microscope.The results show that placement time has little effect on the physical and mechanical properties of YG20 C.With placement time increasing,the coercive force of both YG6 Xand YG6increases at first and then decreases,their hardness and density slowly increase,and relative magnetic saturation and bending strength gradually decrease.

Steel-bonded cemented carbides were prepared by ball milling,die forming and vacuum sintering with atomized iron powders as the bonding phase and TiC particles as the hard phase.The results show that steel-bonded cemented carbides of high densification degree and desired microstructure and properties can be obtained by vacuum sintering at 1 350℃.With increasing TiC content,the cemented carbides have more regular and uniform grains,deceased density and bending strength and increased hardness.When TiC content is 50%,the alloy has the highest density and bending strength of 6.11g/cm^3 and 1 579.48 MPa,respectively.When TiC content is 60%,its hardness reaches a maximum value of HRC86.3.

Characteristics were comparatively analyzed of common hot-filament arrangement in hot-filament chemical vapor deposition of diamond films on cemented carbide tools with complicated shape.Then diamond films were deposited on YG6 cemented carbide drill surface by ultrasound-assisted acid-alkali pretreatment and parallel arrangement of single-row two filaments with the optimized deposition process.Surface quality of diamond films was tested by microscopic examination and drilling experiments were performed on carbon fiber reinforced epoxy resin matrix composites to analyze wear morphology of the coated tools and access quality of the drilled holes.The results show that diamond films can be deposited uniformly on cutting edge with improved filament arrangement method.Diamond films exhibit good adhesion during drilling,and reduce tool wear and burr and edge failure in the access of the drilled holes to a certain extent.

The process is applied of the calcium salt precipitation-Cr removal by washing in dilute hydrochloric acid and W and Mo separation with concentrated hydrochloric acid to recover the tungsten and molybdenum from high-Mo tungsten solution resulted from the waste superalloy treatment.The effects were investigated of pH value of calcium salt precipitation,hydrochloric acid concentration,reaction temperature,reaction time and liquid to solid ratio on separation of tungsten and molybdenum.The experimental results show that during calcium precipitation,tungsten and molybdenum precipitation rate is more than 99% with pH value of 9.5,CaCl_2 excess coefficient of 1.2,and temperature of 80~90 ℃.Chromium can be removed from solid precipitation by washing with dilute hydrochloric acid,and chromium removal rate get close to 100% with 3% hydrochloric acid concentration.In addition,tungsten in the insoluble solid was separated from molybdenum with concentrated hydrochloric acid.Under the conditions of hydrochloric acid concentration of 250g/L,reaction temperature of 65℃,reaction time of 30 min,and liquid to solid ratio of 3∶1,more than 98% molybdenum dissolves in solution,while tungsten exists in solid form of tungsten acid.Thus,the separation of tungsten,molybdenum and chromium is realized.

The solubility of ammonium paratungstate in（NH4）2HPO4-NH3·H2O-H2O system was studied with dissolution equilibrium method.As the ammonia concentration increases,the solubility of APT drops slightly at first and then rapidly rises,and tungstophosphoric acid concentration is significantly reduced in the solution,while the concentration of isopolytungstate and normal tungstate ions significantly increases.With the same concentration of diammonium phosphate,the solubility of APT in（NH4）2HPO4-NH3·H2O-H2O system is much higher than that in（NH4）2HPO4-H2O system.