Influence of preheating and hematite content of clay brick pavers on the characteristics of lines marked with a Nd:YAG laser

This paper reports the clay brick pavers marking by vitrification with a continuous wave Nd:YAG laser (1064 nm). The influence of a preheating and the chemical composition of the bricks on the morphological, visual and dimensional characteristics was studied. The lines marked at room temperature resulted in a discontinuous green glassy phase due to the presence of defects. A remarkable reduction of the defect amount, resulting in smooth, gleaming and darker lines, was obtained when preheating the bricks at 350 °C. The green tone, width, depth and cross-section area of the lines depend on the bricks' chemical composition and thermal condition, as well as, on the laser energy density. Thus, decorative patterns of good visual quality can be marked by laser vitrification on clay brick pavers preheated at 350 °C.