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For a long time, molybdenum powder reduction, molding, sintering process more dependent on the production of accumulated experience. Preparation of molybdenum in recent years with fine tuning of the processing technology, numerical simulation gradually for these three segments of molybdenum powder metallurgy process for the study of micro-evolution, revealing the exact mechanism of molybdenum preparation process, thereby forming process for the realization of molybdenum controllability provide theoretical support. On the substance of these three segments in terms of technology, molybdenum powder reduction stage is a typical phenomenon of diffusion field, you can draw fluids simulation technology; molding, sintering process is a typical non-continuous medium body, and the raw material powder composition is very complex, unable to establish a unified geometric patterns, physical and mathematical models, there is no perfect simulation techniques and simulation software. 

 

(1)Numerical Simulation of molybdenum powder molding process 

 

When molybdenum powder compression molding, powder stress and deformation than solid metal complex can be summarized as two main phases: pre-pressing loose powder particles for polymerization, pressing late for the entity containing pores. Due to the interaction between the powder and the die walls and mechanical action and a lot of friction between the powder particles of different sizes, plus product density during powder compaction, elastic properties, the interaction between the plastic properties of the powder is very complex mechanical behavior , there is not a uniform material model. 

 

At present, because the basic theory of non-continuous media mechanics is not perfect, study abroad mostly as a powder body continuum hypothesis carried out. Powder compaction model can be simplified as elastic stress - strain equation. 

 

(2)Numerical simulation of molybdenum powder sintering process 

 

Sintering is essentially a thermal process. Powder sintering process of consolidation and migration are performed simultaneously heat, consolidation of physical mechanisms include plastic yielding, creep and diffusion. And the powder of the solidification process determines the partial pressure and temperature of the powder consolidation of these physical mechanisms role. Meanwhile, heat the powder solidification migration (mainly heat transfer) and by the local relative density. Therefore, the analysis must be combined sintering thermodynamics. 

 

Due to lack of basic theoretical development molybdenum powder sintering process, can not build enough of partial differential equations, so the numerical simulation of the sintering process, only a single element of the system, a simple case of simple analog molybdenum powder size and morphology under. The simulation results help to analyze the mechanism, but still unable to effectively guide the production process.

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