10.3 固相烧结.ppt

1、第十章 烧结过程10.3固相烧结,3. Solid state sintering,Sintering process is completed in a condition without any liquid phase. This is a way to make some materials with very high melting points.,第十章 烧结过程10.3固相烧结,Simplified model,第十章 烧结过程10.3固相烧结,1. Preliminary stage,1) Model,Ball-surface,Two ball with fixed dist

2、ance,Two balls with changed distance,第十章 烧结过程10.3固相烧结,L/L0 is the shinkage：,Cos1,第十章 烧结过程10.3固相烧结,2) Characters,x/r0.3， L/L00.06 Growth of necks = mass transfer,第十章 烧结过程10.3固相烧结,3) Dynamics at preliminary stage,x: neck radius, r: ball radius, t: sintering,（10-14）,第十章 烧结过程10.3固相烧结,c: concentration of

3、 vacancy,第十章 烧结过程10.3固相烧结,For a conclusion:,For ball-surface model:,Due to y,第十章 烧结过程10.3固相烧结,Al203NaF,第十章 烧结过程10.3固相烧结,Al203,x/r vs. r3/5,第十章 烧结过程10.3固相烧结,Sintering mechanism can be obtained by slope of the line, K can be obtained by the intercept,第十章 烧结过程10.3固相烧结,2. Middle stage of sintering,The p

4、articles are no longer balls.,第十章 烧结过程10.3固相烧结,Pile up method vs. sintering model,第十章 烧结过程10.3固相烧结,2. Characters Neck growth Connect pores； Grain growth Porosity: 5%,第十章 烧结过程10.3固相烧结,3、Dynamics,Pore vol.,Porosity,Vol. of a tetrakaidecahedron,第十章 烧结过程10.3固相烧结,Assume l=2r, J is,Vacancy diffuse flow,第十章 烧结过程10.3固相烧结,积分,气孔体积,第十章 烧结过程10.3固相烧结,第十章 烧结过程10.3固相烧结,3. Late stage of sintering,1) Model Truncated tetrakaidecahedron 2) Characters Closed pores Obvious grain growth Relative density: 95%,第十章 烧结过程10.3固相烧结,3. Dynamics,rarb,第十章 烧结过程10.3固相烧结,tf: the time that all pores disappear,第