Research On Mechanism Of Nanosecond Pulse Laser Marking On Al99.7 Aluminum Ingots Surface

Aluminum ingots with the grade of Al99.7 are regarded as an important raw material in the production of Aluminum and its alloy products.Each Aluminum ingot needs to be affixed with a label sheet containing a production information barcode in the Aluminum ingot production process.Although,it is of great high cost and wasteful for this way.The use of pulsed laser which can directly mark the inf ormation contained in the label on the surface of the Aluminum ingot clearly.The low-cost,non-waste information identification technology becomes an alternative to traditional production methods.At present,it is generally believed that nanosecond pulse d laser material damage is mainly achieved through thermal affection,which can result in complex physical and chemical changes on the surface of the Aluminum material under the action of thermal energy.It can obtain the pattern of different color depths from white,gray and black on the Al99.7 Aluminum surface through adjusting the control parameters of the pulsed laser,but the key factors of coloration about pulsed laser marking Al99.7 aluminum surface are unknown.In view of this,the key issues in na nosecond pulsed laser marking of Al99.7 aluminum have been studied through experiments combined with theoretical analysis,it mainly involves the following aspects:(1)The main laser control parameters were integrated according to the pulse laser working principle.The integrated laser parameters mainly include single pulse energy;scan line spacing and pulse overlap times.The influence of laser parameters on the marking effect of the Al99.7 aluminum surface was obtained by single factor experiments.(2)In order to reveal the key factors of coloration after laser marking Al99.7 Aluminum,the microscopic topography of the marking surface was observed under a scanning electron microscope;the marking surface composition was analyzed by using an energy spectrum analyzer,and spectrophotometer was used to measure the spectral reflectance of the sample surface.It was found that the micro and Nano-structures produced by the pulsed laser energy have different degrees of lowering the spectral reflectance in the v isible light range,so that the marking patterns exhibit different color depths.There is a main reason,micro and Nano-structures formed on the Al99.7 aluminum surface,for obtain the pattern of different color depths through pulse laser.(3)Through establishing a three-dimensional transient heat conduction model of pulsed laser marking materials,numerical simulation methods are used to obtain the surface temperature field distribution of the material under different control parameters.It is found that when the nanosecond pulsed laser acts on the surface of the material,the cumulative effect of heat between adjacent pulses is small,and the damage of the nanosecond pulsed laser to the material mainly occurs during the single pulse process.Based on the temperature field model,the micro-structure of the material surface was analyzed and discussed.