Patent EP-2669041-A1 (EP)
Title: Method for the nanostructuring and chemical modification of ceramic, glass, carbon, boron, silicon and composite materials
Inventor: BRANDL ERHARD
IPC: B23K26/00
Filed: 2013-05-28
Abstract: Producing a surface that has surface structures with dimensions in the sub-micrometer range, comprises completely or repeatedly scanning a material of an outer surface, which does not yet have surface structures with dimensions in the sub-micrometer range and which is accessible to a laser beam irradiation, and in which the surface structures is to be formed, with a pulsed laser beam, such that adjacent light spots of the laser beam completely abut each other. The material of the surface is e.g. at least a ceramic and/or a metal alloy containing heat-conductive carbon-containing particles. Producing a surface that has surface structures with dimensions in the sub-micrometer range, comprises completely or repeatedly scanning a material of an outer surface, which does not yet have surface structures with dimensions in the sub-micrometer range and which is accessible to a laser beam irradiation, and in which the surface structures is to be formed, with a pulsed laser beam, such that adjacent light spots of the laser beam completely abut each other or overlap, satisfying the condition: epsilon is equal to ((P p) 2>x square root of P mx fx alpha x square root of tx square root of K/d 2>x square root of vx square root of T Lx square root of C px square root of lambda )x 10 3>, where: epsilon is 3000-0.07; P p is peak pulse power of the exiting laser radiation (kW); P m is average power of the exiting laser radiation (W); t is pulse length of the laser pulses, preferably 0.1-4000 ns; f is repetition rate of the laser pulses (kHz); v is scanning on the workpiece surface (mm/second); d is diameter of the laser beam on the workpiece; alpha = absorption of the laser radiation of the irradiated material at normal conditions; lambda is wavelength of the laser radiation, preferably 100-11000 nm; T L is melting temperature of the material at atmospheric pressure; C p is specific heat capacity (J/kgx K) under normal conditions; and K is thermal conductivity (W/mx K) under normal conditions. The material of the surface is at least a ceramic, at least one inorganic ceramic green-body, at least one inorganic glass, carbon, boron, silicon, at least one fiber and/or non-fibrous carbon and/or boron-containing composite material with carbon and/or ceramic matrix, at least one inorganic green-body of the above mentioned composite material, at least one metal-ceramic composite material, at least one composite material of a metal and/or a metal alloy containing heat-conductive carbon-containing and/or boron-containing particles and/or fibers optionally and at least partially coated with an oxide layer. The atmosphere in which the process takes place, is a reactive gas or gas mixture with respect to the surface under the process conditions, through which the material which is covered by the surface is chemically modified during or after the scanning with the pulsed laser beam with respect to its composition prior to scanning with the laser beam with the proviso that either before or after the scanning with the laser beam, an adhesion promoter is applied. An independent claim is also included for a workpiece comprising the surface, which comprises the material.