Method of varying a physical property of a material through its depth

摘要

A method is disclosed for varying a mechanical property of a material at two depths. The method involves the application of at least two laser pulses of different durations. The method involves a determination of the density of the material from the surface to each depth, a determination of the heat capacity of the material from the surface to each depth, and a determination of the thermal conductivity of the material from the surface to each depth. Each laser pulse may affect the density, heat capacity, and thermal conductivity of the material, so it may be necessary to re-evaluate those parameters after each laser pulse and prior to the next pulse. The method may be applied to implantation materials to improve osteoblast and osteoclast activity.

主权项

1. A method of varying a mechanical property of a material at different depths “di” and “dj” from a surface of the material, the method comprising:
determining a duration τpi given by of a first laser pulse according to:τpi=di2⁢ρi⁢cpi4⁢kti, where ρi is a density of the material between the surface of the material and the depth di prior to exposure of the material to the first laser pulse, cpi is a heat capacity of the material between the surface of the material and the depth di prior to exposure of the material to the first laser pulse, and kti is a thermal conductivity of the material between the surface of the material and the depth di prior to exposure of the material to the first laser pulse; exposing a region of the material to the first laser pulse for the duration τpi; determining a duration τpj second laser pulse that is a different duration than the duration τpi of the first laser pulse according to:τpj=dj2⁢ρj⁢cpj4⁢ktj, where ρi is a density of the material between the surface of the material and the depth di after exposure of the region of the material to the first laser pulse, cpj is a heat capacity of the material between the surface of the material and the depth dj after exposure of the region of the material to the first laser pulse, and kti is a thermal conductivity of the material between the surface of the material and the depth di after exposure of the region of the material to the first laser pulse; and exposing the region of the material to the second laser pulse for the duration τpj.