Ce4+离子对电沉积金属铬的影响

用电沉积方法从含有CrO。及少量HzSO。的电解液中制备的金属铬镀层，具有极好的反光性能及装饰性能，应用十分广泛．但长期以来，一直采用高CrO。浓度（2509·L－‘以上）、高温度（50”C以上）的工艺，加上该工艺阴极电流效率极低（10％左右）＊；环境污染、材料和能源浪费严重．近年来，在改善镇铬工艺方面的研究取得了很大的进展，其中使用各种添加剂的尝试得到了一定的成效，如使用含有卤素化合物的添加剂可提高镀铝的阴极电流效率［2－1使用含稀土化合物的添加剂可以使电解液中CrO。浓度和操作温度大大降低，而阴极电流效率却有所…

The Effect of Ce~(4 ) Ion on the Electrodeposition of Metallic Chromium

It is found through experiments that metallic chromium coating with fine grained and compact crystal structure and high lustre degree can be obtained at near room temperatures by addition of 1.2g.L-1 Ce4 ion in a clirondum plating bath containing 200g.L-1 CrO3 and 2g.L-1 H2SO4. As compared with the traditional chromium plating technology, the new technology can decrease the CrO3 concentration in the plating bath by one-fifth, and decrease the operating temperature by about 30 degrees. The results of X-ray diffeaction experiments reveal that the electrocrystallization of metallic chromium in the coating is orientated along the (200) crystal plane. Hence, the coating eAnbits high degree of lustre. The results of cathodic polarization curve and differential capactiance curve mesearements show that Ce4 ion can be adsorbed specifically on the cathode surface. This increases the cathodic polarization value and thus malles the rate of nucleation much faster than that of crystal growth, leading to the formation of fine grained chromium coating. Consequently, the lustre degree of the chromium coating is increased.