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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.
Comparative studies of the corrosion and long-term stability of vitrified e-filter dust from waste incinerators, granules from hightemperature waste incineration plants and a model glass
The objective of this study was to describe the corrosion behaviour of vitrified residues of municipal waste incinerators by using standardized short-term and long-term leaching and corrosion test methods. The results for the vitrified product were compared to the results for granules from high-temperature waste incineration plants and a model glass. The test methods used in this work are, on the one hand, a German and a Swiss test [1 and 2] to describe the possibility for the disposal of waste and, on the other hand, test methods [3 and 4] to characterize the corrosion behaviour of glass products. The results according to the different methods and their changing test parameters like temperature, corrosion time and leaching Solution are presented.
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.
Machining of silica glasses using excimer laser radiation
Various silica glasses were engraved deliberately by excimer laser radiation using wavelengths of 308 and 248 nm. The ablation of different samples was investigated by systematic Variation of the processing parameters. The ablation rates were determined using profilometry and gravimetric measurements by evaluating the processing quaUty and the morphology of the processed surfaces was considered. The phenomenon of ablation is explained as a non-linear interaction of the laser beam and the glass. The experimental results show that the ablation behaviour of silica glass depends on the wavelength and the intensity of the laser radiation, on the surface quahty and the degree of purity of the glass. Although high ablation rates were obtained, the suitability of excimer lasers for micromachining is restricted due to the rough surface morphology and poorly defmed edges.