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.

In the paper are reviewed the preparation,features,crystallization,microstructure and properties of Zr₅₅Al₁₀Ni_5Cu₃₀.

In this paper were summarized some new sintering techniques and their properties for nano-grained cemented carbide such as pressure sintering,field assisted sintering,microwave sintering and two-stage sintering.The test results have well demonstrated the feasibility of conventional vacuum sintering in nano- structured cemented carbide preparation.

In the paper is reviewed the study of strength and structure of WC-Co hard alloy. It indicated that WC-Co hard alloy is characteristic of particle compound reinforcing material,based on which investigation is made into the microstructure and preparation technology of the said alloy.

In the paper are summarized the market development of tantalum and niobium electrolytic capacitors and progress on the development and manufacturing of Ta/Nb capacitors both at home and abroad.