Study On The Preparation Technology Of Micro Powder By Physical Method

The Al particles,polyimide particles and optical glass were super pulverized respectively by the three pulverizing mechanisms of blade impact crushing,ball milling and grinding.The effects of pulverizing mechanism on the particle size of powder were discussed.The impulse coupling coefficient of each particle size of the three materials was measured when the powder of the three materials was ablated by pulsed laser as working material.The 325 mesh powder of the three materials was ablated by laser with different pulse energy and different frequency respectively and the impulse coupling coefficient was measured.The effects of particle powder size,laser energy and laser frequency on the impulse coupling coefficient were discussed.The following conclusions were obtained:(1)Under the same pulverizing conditions,the powder particle size of Al particles,polyimide particles and optical glass was smaller and more uniform,and the powder particles were more nearly spherical by blade impact crushing;(2)In the blade impact crushing,the particle size of Al powder,polyimide powder and optical glass powder decreased with the prolonging of time;(3)The powder particle size of the three materials pulverized in the vacuum and the atmospheric environment was almost the same.Vacuum environment had little effect on the results of pulverizing;(4)The powder particle size of the three materials all had a tendency to become larger after the addition of liquid nitrogen,and the addition of liquid nitrogen was not conducive to the reduction of particle size;(5)With the decrease of the particle size,the impulse coupling coefficient of Al powder and polyimide powder had an increasing tendency and the latter reached the maximum 29.4 dyne/J.While the impulse coupling coefficient of optical glass powder was not very sensitive to the powder particle size;(6)Along with the increase of laser energy,the impulse coupling coefficient of the three kinds of powder had an increasing tendency.However,the impulse coupling coefficient of polyimide powder reached the maximum 44.0 dyne/J when the laser voltage was 600 V and then decreased.(7)Along with the increase of laser frequency,the impulse coupling coefficient of the three kinds of powder had an increase tendency.However,the impulse coupling coefficient of polyimide powder reached the maximum 29.4 dyne/J when the laserfrequency was 8 Hz and no longer increased with the laser frequency increased.