The effect of mechanical activation on leaching kinetics of molybdenite is studied.Mechanical treatment causes slight depression of apparent activation energy for leaching molybdenite in HNO_3-H_2SO_4 solution.After 40-minute intensive mechanical activation in planetary centrifugal ballmill,the activation energy becomes 6kJ/mol less than that for leaching of non-activated one.We ascribe this to the layered structure of molybdenite.When violent mechanical force is acted on molybdenite crystal,it is easy to obviate such force through inter-layer slip since the Van der Vals force between S-S layers is very weak.

The reaction expression of precipitation and crystallization is put forward based on the pH value change during neodymium chloride precipitation by ammonium hydrocarbonate.Study is made of the influence of feed rate,dosage,aging time on the process of neodymium carbonate crystallization.The technological condition for rapid precipitation of crystalline neodymium carbonate is verified.

With the depletion of wolframite,scheelite concentrate substitute has become the developing trend of the future extractive metallurgy of tungsten.For the hydrometallurgical processing of scheelite concentrate by fluoride solution,the equlibrium concentration logarithm diagrams of every component is drawn according to thermodynamics calculation,under conditions of 0.10 mol/L and 0.12 mol/L fluoride concentration.Based on the logarithm diagram,the thermodynamic analysis is made of scheelite leaching by fluoride solution.

Study is made of the impact of plating solution composition and technological conditions on the sedimentation velocity of Ni-B alloy. Proper technological conditions of chemically-plated Ni-B alloy is selected, based on which amorphous Ni-B alloy layer is obtained containing 4.508% boron with good corrosion resistance.

The influence of sintering temperature on microstructure and mechanical properties of high-W tungsten heavy alloys has been studied.The results show that microstructure and mechanical properties of W-based heavy alloys are closely related with sintering temperature.Good microstructure and mechanical properties can be obtained at proper sintering temperature.Low sintering temperature,uneven distribution of binder,high sintering temperature,coarse tungsten grain will result in lower mechanical property.

Study is made of the microstructure of blue tungsten by patented powder sampling technology and TEM.The results showed that the blue tungsten particles are polymerized from single crystal into multi-crystalline particles,resulting in blue tungsten agglomerate with composite phase composition in the powder.

The WC-Co-RE powder was prepared by high-performance ball milling.The structure,morphology and phase change of nano-crystalline powders were analyzed by means of XRD (x-ray diffraction),SEM (scanning electron microscope) and DTA (differential thermal analysis).The results showed that the nano-crystalline powder with grain size of 8.45 nm was obtained by 45-h ball milling and addition of trace rare earth was effective to diminish the grain size of the powder.The grain size of rare earth doped powder became two times smaller than that of the undoped powder,and the decrease trend of the grain size of the powder accord with linear regression equation after 25～45 h-ball milling.The XRD peak of Co phase disappeared after 25-h ball milling.A sharp peak of heat release at 597 ℃ was emerged in DTA curve.Upon the solidification,the powder exhibits fine grain size and good mechanical property.

Yttrium oxide nano-powder is prepared by liquid-phase precipitation using oxalic acid as the precipitant.Study is made of the solution in respect of pH value,concentration,reaction method, dispersing agent and calcinations temperature through SEM and DTA analysis of the powder.20～50 nm.Yttrium oxide powder is produced under the resultant ideal technological conditions.

Detailed study is made of the color reaction of Ti (Ⅵ) with Chlorophosphonazo Ⅲ and the resultant complex compound at λ_max=690 nm and apparent apsorption coefficient 1.47×10~5 L·mol^-1·cm^-1.Beer's law is followed when Ti is at 0～1.0 ug/mL.The proposed method is satisfactory for determination of trace Ti in reduction iron powder and PM Ti powder.

New development of gradient cemented carbides is summarized in this paper.The technology,principle of carbon-adding sintering are introduced.The application and prospects of gradient cemented carbides are also discussed.