Study On The Selective Etching Technology Of Sapphire

Sapphire has the advantages of high hardness,good chemical stability,high melting point and good light transmission.It is an important material for optical elements,masks and aircraft windows.Sapphire is difficult to be processed by traditional methods because of its great brittleness and chemical stability.Selective laser lithography is a composite processing method including femtosecond laser scanning and chemical corrosion,by optimizing the femtosecond laser processing parameters to obtain good surface topography,improve processing efficiency and surface quality by using two-dimensional ultrasonic vibration assisted chemical etching.The improvement of surface quality of sapphire processing area was studied by combining jet technology with chemical etching.The main work of this paper is as follows:Optimize the laser processing parameters: accurately calculate the laser ablation threshold of sapphire,which is 2.0296J/cm2.According to the projection area of focus,derived in the general formula between surface laser scanning speed and pulse number of sapphire.Cross line scanning path is proposed,and Simulation of surface topography,when the scanning line spacing,the focus of long axis parallel to the machined surface,the greater the focus aspect ratio,residual height of the larger,is perpendicular to the long axis conclusion the machined surface is opposite.Focus size smaller,residual height increasing.When the focus size is determined,the larger the line spacing is,the greater the residual height is,and the shape of the two relation curves is consistent with the focus arc contour.The laser processing experiments show that the smaller the laser power is,the smaller the laser heat affected zone(the smaller the diameter of the ablated hole),and the number of pulses has little influence on the diameter of the ablated hole.Two dimensional ultrasonic vibration device and chemical etching were developed.HF and concentrated H2SO4 were used to carry out ultrasonic etchingexperiments on sapphire specimens after laser processing.The orthogonal experiment showed that the 40% HF sapphire etching concentration,etching of 1H under the condition of surface quality of sapphire is better,can reduce 0.5382 m,compared to the non-ultrasonic vibration etching removal rate is increased by about81%,and can reduce the corrosion layer about 69% generation.In addition,etching experiments with concentrated H2SO4 solution confirmed that the higher the temperature,the better the etching effect,but much less than the etching effect of HF solution.With the combination of technology and chemical etching technology jet,were acid etching and abrasive jet etching experiment,analyzes the effect of flow rate on the effect of etching,and verify the feasibility of abrasive polishing and etching liquid mixture.The results show that the removal rate of surface material increases with the increase of acid jet velocity,and the trend increases gradually.Abrasive jet acid experiment,found that the polishing and etching liquid processing immediately after mixing the material removal effect than acid jet,and the effect of abrasive water jet polishing is more that abrasive jet etching plays the main role,polishing and etching liquid mixing time is longer,the effect is worse.