Solid State Sintering

The growth of the sinter bond from an initial loose powder contact is characterized as the initial stage of sintering. In this stage, the neck size is sufficiently small that neighboring necks grow independent of one another. The initial stage ends when the necks begin to impinge. Various laws link the neck size ratio to other useful sintering parameters, including shrinkage, surface area, and density.

Computer analysis of initial stage sintering has been a popular theoretical topic. Early codes assumed sintering occurs between two equal spheres with conservation of volume by a single mass transport mechanism. Thus, any change in the neck size must have a corresponding functional relation to the volume of material deposited at the neck. There is a gradient in the curvature over the sintering geometry. The curvature gradient drives the mass flow, by any of the mechanisms presented, to smooth the surface and possibly densify the structure. At any point on the neck, there is a surface contour defined by the function S(v), where v is a parameter describing the spacial relation between the x-y coordinate system and surface position. Consider surface transport controlled sintering where at any point on the surface curve the following exists:

0 0

Post a comment