YAG：Ho^3＋,1%Yb^3＋nanocrystal was synthesized by a sol-gel process from the mixed solution containing aluminum nitrate and rare earth oxide. The technological conditions to synthesize its xerogel were determined by orthogonal tests. DTA-TG,XRD and TEM techniques were used to study the synthe- sis process of the xerogel and characterize the crystal structure and morphology of the prepared YAG.1 Ho3＋ , 1%Yb3＋. The results show that monophase YAG crystallite can be formed without any intermediate phase after calciningthe xerogel at 1 200℃ Absorption spectrum and upconversion emission spectrum of YAG. 1 % Ho3＋, 1% Yh3＋ nanocrystal were investigated. Yb3＋ ions have the function of transferring energy in the luminescence process. Contributed to the Ho^3＋ transition, strong red and green upconversion fluorescence can be observed centered at 650 nm and 540 nm,respectively.

Si-Y2O3 infiltration coating was prepared from the Nb-Si-based ultrahigh-temperature alloy surface by the pack infiltration of heating for 10 h at 1 050 ℃ ,1 150℃ and 1 250℃ ,respectively. The effects of Y element on coating morphology and crack formation were investigated by SEM, EDS and XRD. Both prepared by the pack infiltration at the same temperature and duration,Si-Y2O3 infiltration coating was compared with single Si infiltration coating. The results show that the upper part of the outer coating layer is composed of （Nb, M）Si2 columnar grains, and the lower part composed of （Nb, M）Si2 equiaxed grains. The coating microstructure can be refined obviously by adding 0.75% （mass fraction） Y2O3 to the pack mixture. The total length of either vertical cracks or horizontal cracks is relatively small when the Y2O3 amount in pack mixture is in the range from 0.5% to 0.75%.

The laser sint alloy and TiH2. The mi formation mechanisms cussed. In the sintered ering experiment was carried out on the powder mixture of self-melting nickel-based crostructure of sintered samples was characterized by XRD,SEM and EDX. And the of porous structure and precipitated phase in sintered samples were simply dis samples, the reinforcing phases TiC and TiBz are in-situ synthesized and structure is also formed. A large number of micron-sized pores are uniformly dispersed in the matrix as the high-temperature strengthening phase CrB with a radial or acicular-lobate shape. porous as well

High-purity Er2O3 ceramic target material of about 90% relative density was prepared by lowtemperature nonpressurized sintering at 1 450℃ and with Er2O3 nanopowders as its raw material. The target materials prepared with Er2O3 nanopowders of various shape were analyzed from their fracture appearance and density. The results show that the target material prepared by low-temperature nonpressurized sintering and with three-dimensionally subsphaeroidal Er2O3 nanopowders as its raw material has the optimal performance.

The compound carbide （W-Ti-Ta-Nb）C was prepared by direct reduction. The influences of different calcination temperature and duration and mixing time on the contents of solid solution phase,combined carbon and free carbon in the prepared （W-Ti-Ta-Nb）C were investigated. By orthogonal experiments, the optimal carbonization parameters are obtained as follows：calcination temperature 2 100℃ ,calcination duration 50min and mixing duration 3 h. The final product is completely in the state of solid solution phase,where the content of combined carbon is 10.67% and free carbon is 0.15%.

A （Ti,V）C steel bonded carbide was prepared by in-situ sintering with the powders of titanium, ferrovanadium, carbon, ferrochromium, ferromolybdenum and iron as its raw materials. The phase composition,microstructure and micro-area composition of the carbide were studied by XRD, SEM and EDS. And the bending strength of the carbide sample was also measured. The results show that the morphology of （Ti,V）C reinforcing phase in the carbide is more regular and rounding than TiC particles. The bending strength is high. Furthermore, cleavage of reinforcing phase, quasi-cleavage of matrix and dimple are presented in the fractographic appearance of the carbide sample.

The mathematical model for the cold rolling force of titanium plate is studied to control the technological parameters. Based on Maple software, titanium plate cold rolling experiments and multivariate nonlinear regression,average titanium plate rolling pressure model is obtained and then rolling force model is established. Compared with the measured value of titanium plate rolling force, the average relative error of the calculated value from the model is 8.0 %.

Quality control is discussed in respect of material selection, carbonization process and pulverization classification during the production of high-quality ultrafine WC powders by conventional process. Some methods to measure the particle size of ultrafine WC powders are compared. The results show that the BET measured value is the closest to the actual particle size.

The silver in the supernatant,produced from copper anode slime pretreatment is recovered by silver precipitation with NaI-transformation with Na2 S and then HNO3. And the optimal process conditions are determined. The results show that the silver recovery canreach 96.56% ,the silver content in the precipitated Ag solution is reduced down to 4 mg/L and the purity of crude silver is above 95%.

The mass fraction of the hydrogen in high-purity titanium metal was determined by high frequency induction-thermal conductivity method. The influences of induction current, crucible material, fluxing agent,blank value,minimum analysis time and sample weight on the determined result were emphatically discussed. And a method to determine the hydrogen in high-purity titanium metal was established. The results show that the relative standard deviation of the hydrogen mass fraction determined by the above method is 6. 3%, and the recovery of standard addition is 98%-106%. The determination conditions of partial hydrogen content in titanium metal were studied by a combined analysis program. Based on peak separation experiments, each partial hydrogen content was calculated.