Further progress in laser welding of ceramics

Laser welding of ceramic parts of alumina with two laser beams has been almost done successfully at the Laser Centre of Mittweida since 1986. The progress in solving the problems of welding this material by means of laser radiation is shown in the following paper.An introduction concerning some welding-related properties of ceramic materials will be given: thermal properties - such as heat conductivity and resistance to thermal shocks will be discussed. Measurements of absorptivity at 1060 nm show that the low absorption coefficient increases above temperatures of about 1000 K.Investigations of thermal stresses, which must be minimised for crackfree welding, show the necessity of preheating. One can preheat the whole workpiece or part of it using different preheating methods.The welding method for alumina with two laser beams (one is used for preheating) shows how to use different laser wavelengths for getting various shapes of the welding heat source due to the different value of absorptivity.An investigation of the laser welded parts of alumina reveals the different micro structure in the heat affected zone and grain sizes within the melted zone which vary with the cooling rate.It should be possible to use this new welding technique for the realisation of more complicated shapes of ceramic parts in comparison with conventional machining of sintered parts.Laser welding of ceramic parts of alumina with two laser beams has been almost done successfully at the Laser Centre of Mittweida since 1986. The progress in solving the problems of welding this material by means of laser radiation is shown in the following paper.An introduction concerning some welding-related properties of ceramic materials will be given: thermal properties - such as heat conductivity and resistance to thermal shocks will be discussed. Measurements of absorptivity at 1060 nm show that the low absorption coefficient increases above temperatures of about 1000 K.Investigations of thermal stresses, which must be minimised for crackfree welding, show the necessity of preheating. One can preheat the whole workpiece or part of it using different preheating methods.The welding method for alumina with two laser beams (one is used for preheating) shows how to use different laser wavelengths for getting various shapes of the welding heat source due to the different value of absorptivity.An investig...