Model for patterned erosion

Abstract

Sandblasting is a well-known process for patterning window glass and mirrors. The technique is now being developed for the production of technical structures with high precision. This paper presents a model for the evolution of powder-blasted structures in masked glass substrates. The model assumes that the shapes originate primarily as a result of the dependence of erosion on impact angle. At second strike the rebounding particles give an extra contribution to the erosion process. An analytical solution is presented for the model without the second strike. Although the solution was sought for erosion of grooves, it can also be used to construct the shapes of other mask patterns. The model containing the second strike has been solved numerically. The results have been compared with experimentally obtained shapes. The model gives a good qualitative description of the observed phenomena. In quantitative terms, it compares reasonably well with experimental results, considering the simplifications in the model. Effects of particle size, mask hindering and mask wear were not included and the rebound characteristics of particles were included in a simplified form only. For improvement of the model more experimental data is needed in these fields.