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Firimg PbO - free glass enamels using the CW - CO₂ laser
The firing of glass enamels, which are applied to decorate glass products, is usually done in a furnace. Α new and suitable technique for firing glass enamels is to make use of the high-power CW-CO₂ laser. Its be am (wavelength 10.6 μm) induces a very fast heating of the enamelled glass within a small surface layer. This makes it possible to fire glass enamels at temperatures above 1000°C, without any deformation of the Substrate glass body In this temperature ränge an amount of the harmful component PbO in t he glass enamel is n o longer necessary The PbO-free glass flux of the enamel is made easily by milhng the Substrate glass (float glass). The gloss and smoothness of the laser-fired enamel are comparable to the conventionally fired enamel. The absence of PbO and the high firing temperatures are very advantageous to the chemical resistance of the enamels, meaning excellent dishwasher durability.
Enamelling of glass by CO₂ laser treatment
Decoration of glass using enamel is interesting for hollow glassware as well as for flat glass sheets. Laser radiation can be used advantageously to increase the temperature of the product locally. The reactions which take place during CO₂ laser heat treatment of a conventional PbO-containing frit are discussed intensely. Pyrometrical temperature measurements accompany the experiments to investigate the temperature development during CO₂ laser irradiation. At temperatures above Tg optimal results concerning low surface roughness, high brightness and intensive colouration are obrained without deformation of the shape of the product. Very promising results show that higher temperatures can be achieved by laser application and therefore PbO-free frits can be used.