Abstract
For the purpose of the application of laser welding in jointing of dental prostheses, the basic study was systematically performed in case of Ag-Pd-Cu-Au alloy, using a pulsed Nd: YAG laser. This article discribed the effect of the conditions of laser irradiation and specimen surface upon penetration.
Specimens were rolled sheets of 3 mm thickness alloy. Specimens were treated by three surface treatments; polished with emery paper (# 400), with alumina powder and with emery paper then oxidized (CuO, Cu2O). The laser beam were irradiated on these specimens at various output energy levels and defocused distances from a focal point of a lens.
Increase in the laser power density by increasing the irradiated energy or by decreasing the defocused distance brought the increase in penetration depth. Under the same irradiation condition, the deepest penetration was obtained in the specimen with oxidized surface. And the deep penetrated fusion zone had rough surface.
The above-mentioned results exhibited that the penetration can be controlled by laser irradiation or surface conditions of specimen. Therefore, even with low laser output energy a deep penetration can be obtained, providing the absorptance raise by surface treatment.
