ZnS nanocrystals were synthesized by direct reduction, with zinc sulfate as the sulfur ＆ zinc source and hexamethylene tetramine as the reducer. The structure and morphology of the as-prepared samples were characterized by XRD and SEM,and the result shows that they are pure face-centered cubic ZnS nanocrystals. Meanwhile,the influences of reaction time and temperature on the products were studied,and the reduction mechanism was also investigated.

Cu-Ni-Fe coating was prepared on the surface of pure tungsten by vacuum deposition,and the dif fusion bonding of pure tungsten and copper was carried out with the coating as the middle layer. The mi crostructure and composition distribution at the interface of the W/Cu-Ni-Fe coating/Cu joint were investigated by OM, SEM, EDS, microhardness tester and shear test. The results show that at the interface of vacuum deposited W/Cu-Ni-Fe coating,a large number of W atoms go into the Cu-Ni-Fe coating by reaction diffusion to form a 6μm wide FeW-rich interracial layer. At the Cu-Ni-Fe coating/Cu interface formed during diffusion bonding, the microstructure is homogeneous and compact but copper base metal has a small amount of micropores. The shear strength of the W/Cu-Ni-Fe coating/Cu joint reaches 185 MPa,and fracture failure occurs mainly in tungsten base metal and FeW-rich interracial layer.

The current development and preparation methods of rapidly solidified high-silicon aluminum loys are introduced,and their development trend is prospected.

湖南稀土金属材料研究院始建于1958年，为国有独资科技型企业，是我国最早从事稀土材料应用研究与开发的单位，是军工稀土新材料研制开发的配套单位。该院已通过军品科研生产许可认证和ISO9001中国质量认证。

Tungsten oxides in different valence states were prepared by hydrogen reduction of yellow tung- sten at 660 ℃for different time,and their morphology and structure characteristics were observed and ana- lyzed. Nanometer W or WC powders were prepared by reducing WO3. The growth mechanism of nanome- ter powders during phase transformation was discussed. Effects of morphology and structure genetic char- acteristics of raw material powders on particle size uniformity of the products were analyzed. The selection of porous tungsten oxide powders of single-phase composition, high purity, fine and uniform particle size as the raw material is good for preparing fine and uniform nanometer W or WC powders.

Technical conditions were studied for cobalt leaching from iron ore tailings in citric acid-ammoni- um bifluoride system. The results of orthogonal experiments show that reaction temperature is the primary influencing factor of cobalt leaching rate, reaction time and ammonium bifluoride concentration are second- ary,and citric acid concentration is the last one. The more reaction time and ammonium bifluoride concen- tration, the higher cobalt leaching rate. The results of the further experiment to determine the optimal con- ditions show that cobalt leaching rate can reach 90.61% with 100 ℃ reaction temperature, 20 g/L citric acid concentration,40 g/L ammonium bifluoride concentration and 4.0 h reaction time.

Vanadium was recovered from vanadium-containing ceaching solution with high iron concentra- tion by reducing precipitating-redissolving process. The process steps of pre-neutralizing of leaching solu- tion,preparation and redissolving of vanadium acid concentrate and the influence factors of each link were investigated. The results show that this process can recover vanadium and prepare qualified Vz 05 , but the overall recovery rate of vanadium is relatively low.

Germanium was recovered from fly ash by ammonium fluoride-sulfuric acid leaching. In the process ,ammonium fluoride reacts with sulfuric acid to generate hydrogen fluoride as the destruction rea- gent of silica and calcium oxide in fly ash,sulfuric acid serves as the destruction reagent of magnesia,and sodium chlorate serves as the oxidant to oxidize Ge（ Ⅱ ） into Ge（Ig）,which can he dissolved into the leac- hing solution by sulfuric acid. Finally, germanium is precipitated with tannic acid. The above process has the advantages of high germanium recovery,low cost, low pollution and so on. Under the optimal technical conditions,the germanium recovery reaches 80.12% and the grade of resultant germanium concentrate is up to 4. 69%.

The characteristics of current mineral resources in China are described. The latest development of complex ore processing techniques is reviewed, focusing on molybdenum-containing mixed mineral and high iron nickel laterite ore. Professional teaching reform measures are put forward of promoting class by scien tific research experiments.

Al2O3 coating was prepared on the surface of γ-TiAl alloy by sol-gel method, and the high tem- perature oxidation kinetics of the alloy substrate and the coated sample was researched by isothermal oxi- dation experiment. The algorithm of the kinetic equation was derived, and the thermal stress between oxide film and substrate was estimated. The results show that the kinetics of the blank sample follows the cubic law in the preceding period of high temperature oxidation, but then follows the linear law. However,high temperature oxidation kinetics of the coated sample follows the linear law first and then the parabolic law. The oxidation rate constant of Al2O3 coated sample decreases by nearly 90% compared with the blank con- trol sample. Al2O3 coating can improve cyclic oxidation resistance of the alloy by reducing the thermal stress between oxide film and substrate.