| 2. | For electrodeposition by dc methods , the metals deposite uninterrupted and the particles were also embeded uninterrupted into the coatings ; for electrodeposition by pc method , the particles with biggish volume were desorbed from the coatings and returned to the electrolyte again owing to the presence of pulse interval ; for electrodeposition by prc method , the particles carried positive charges are much more easy to desorb from the coatings owing to the effecf of reverse pulse current combined with pulse interval , in addition , the reverse pulse current also could dissovle the metals , further accelerates the desorption of particles , thus the particles size embeded in the coatings by prc method is the least
直流电沉积时,基质金属的沉积连续进行,粒子在电极表面不间断嵌入镀层;单脉冲电沉积由于脉冲间歇的存在使得具有较大体积的粒子会脱附,重新回到溶液中;采用周期换向脉冲时,反向脉冲电流使表面荷正电的较大的粒子更易从电极表面脱附,同时,反向脉冲电流对基质金属的溶解作用,也会促进粒子的脱附,因此镀层中复合粒子尺寸最小。随着镀层中粒子复合量的增加,三种镀层的晶粒都明显细化,说明al _ 2o _ 3的存在阻止了晶粒的长大,提高了电沉积过程中晶核的形成速率。 |
