脉冲频率对纯钛微弧氧化膜生长特性的影响

Eflfects of Pulse Frequencies on Properties of MAO Coatings on Pure Titanium

在Na2CO3-Na2SiO3电解液中,利用微弧氧化技术在纯钛试样表面制备了氧化膜,并研究了脉冲频率(500-8000Hz)对膜层生长、相组成及表面形貌的影响．结果表明:当脉冲频率 <2000Hz时,膜层的生长速率随频率增加迅速减小,当>4000Hz时,其生长速率几乎和频率无关．微弧氧化膜主要由锐钛矿和金红石相TiO2及少量不饱和氧化物TiO2-x(0．02<x<0．07) 组成,其中锐钛矿和金红石相TiO2的相对含量与频率无关,而TiO2-x随频率的增加而逐渐减少．氧化膜表面多孔,随着频率的增加,膜表面的粗糙度和微孔尺寸逐渐减小,而微孔的密度逐渐增加．

Microarc oxidation coatings were prepared on pure titanium substrates in a Na2CO3 and Na2SiO3 electrolytic solution by microarc oxidation with the pulse frequency of 500-8000Hz, the effects of pulse frequencies on growth kinetics, surface morphology and phase composition of the coatings were studied. The result shows that the coating growth rate is dependent on the pulse frequency. When the frequency is less than 2000Hz, with the increase of frequencies, the coating growth rate decreases sharply, while the frequency is greater than 4000Hz, it keeps almost invariable with the treating frequency increased. The coatings consist of plentiful rutile and anatase, and a small quantity of unsaturated oxide （TiO2-x, 0.02〈 x 〈0.07）. The relative content of rutile and anatase keeps invariable with the variation of the frequency, while TiO2-x reduces gradually with the increase of the frequency. The coating surface is porous, with the frequency increasing, the roughness and micropore size of the coating surface decrease gradually, and the pore number increases little by little.