Nanolayer Surface Phase Change in Self-Healing Materials

The phase change problem in a semi-infinite medium where temperature and concentration are coupled is solved for variable diffusivity. An integral technique is used to solve for concentration and temperature penetration lengths and velocity of change. Surface conditions are held constant whereas diffusivity is allowed to vary slowly corresponding to phase change in the matrix. An analytic solution for variable properties under these conditions is obtained using the Kirchhoff transformation. Penetration lengths are analytically evaluated. Aperturbation analysis allows the boundary layer lengths to be estimated, whence the two parameters can be compared. Dimensions obtained by the simulation show that nanomaterial thicknesses are attainable in the boundary layers. Application to phase change concepts relating to self-healing materials is illustrated for porous surface layers.