Variation of vapor pressure with particle size S.J.T.U. Phase Transformation and Applications The pressure on a small droplet is the sum of the imposed gas pressure and the internal pressure generated by the surface tension of the material 2mY=m2△p △p= π ViPT RTIn Figure 4.7 The force holding two hemispheres together is 2mry:the force pushing them apart is AP, RTI- where△P=2ylr. The vapor pressure above the small particles is greater than the vapor pressure I=Y (2x above the large particles.Material would RT then move through the gas phase from Coarsening SJTU Thermodynamics of Materials small particles to largerones..Coar Spring 2018Phase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2018 © X. J. Jin Lecture 8 Chemical equilibrium Variation of vapor pressure with particle size The pressure on a small droplet is the sum of the imposed gas pressure and the internal pressure generated by the surface tension of the material r = r p 2 2   r p 2  = e Vl pT RT   = ln e l RT r V    ln 2  =            = RT r V l e    2 ln The vapor pressure above the small particles is greater than the vapor pressure above the large particles. Material would then move through the gas phase from small particles to larger ones. Coarsening