Application specific intensity distributions for laser functionalization of (nano-)ceramic coatings as wear protection

The laser based functionalization of thin sol-gel based (nano-)ceramic coatings requires a two-step thermal process. Fi rs t, the solvent material, in which the ceramic i s applied, needs to be removed in a drying process. Afterwards, during a second step that removes the last organic constituents, the ceramic’s full potential as wear protection coating is achieved via cross-linking. As both steps require s ignificantly different processing temperatures, the material usually is treated in two consecutive laser based processes. Thus, the process efficiency can be increased to a great extent by us ing application specific beam profiles. These beam profiles can be designed in such a way that they combine both s teps into a single one by ra ising the induced material temperature stepwise. To this end, we present a method to obtain an application specific intensity distribution that induces a prescribed temperature profile in a layered system consisting of a metal substrate and a thin (nano-)ceramic coating. This is done by solving an inverse heat conduction problem using the conjugate gradient approach with adjoint problem. Afterwards, we give the design of a free-form optic that produces the obtained intensity distribution in an experimental setup. We conclude our work by veri fying our approach us ing the commercial FEM software ANSYS.