四硼酸锂电解液浓度对Zr-4合金微弧氧化陶瓷层的影响

Effect of Concentration of Lithium Tetraborate Electrolyte on the Micro-Arc Oxidation Ceramic Layer on Zr-4 Alloy

为了提高Zr-4合金在核工业中的服役性能并避免引入杂质元素,以Li_(2)B_(4)O_(7)为电解液在Zr-4合金表面制备微弧氧化陶瓷层,研究了Li_(2)B_(4)O_(7)浓度对微弧氧化陶瓷层的物相组成、微观形貌、膜层厚度、硬度、粗糙度、耐磨损和耐腐蚀性能的影响。结果表明:当ρ(Li_(2)B_(4)O_(7))=3~15 g/L时,随着Li_(2)B_(4)O_(7)浓度的增加,电解液的电导率持续增加,陶瓷层的粗糙度总体持续增加,只在电解液浓度从6 g/L变化到9 g/L时稍有下降,微弧氧化陶瓷层厚度先在ρ(Li_(2)B_(4)O_(7))=3~9 g/L范围内持续下降,后在ρ(Li_(2)B_(4)O_(7))=9~15 g/L范围内上升;陶瓷层的硬度先是在ρ(Li_(2)B_(4)O_(7))=3~6 g/L范围内下降,后在ρ(Li_(2)B_(4)O_(7))=6~15 g/L范围内上升。陶瓷层全部由单斜相氧化锆(m-ZrO_(2))构成。随着电解液中Li_(2)B_(4)O_(7)浓度的增加,陶瓷层的孔隙率下降,微孔尺寸变化不大,陶瓷层的摩擦系数在ρ(Li_(2)B_(4)O_(7))=3~12 g/L范围内持续增加,在ρ(Li_(2)B_(4)O_(7))=15 g/L时下降。综合比较,在Li_(2)B_(4)O_(7)浓度为15 g/L的电解液中可以获得厚度适中、硬度较好、表面平整连续、孔隙率和孔径尺寸均较小、耐磨损和耐腐蚀性能均较好的陶瓷层。

In order to improve the service performance of Zr-4 alloy in nuclear industry and avoid introducing impurity elements,the micro-arc oxidation ceramic layer was prepared on the surface of Zr-4 alloy with Li_(2)B_(4)O_(7) as electrolyte.The effects of lithium tetraborate concentration on phase composition,microstructure,film thickness,hardness,roughness,wear resistance and corrosion resistance of micro-arc oxidation ceramic layer were investigated.Results showed that as the concentration of Li_(2)B_(4)O_(7) increased in the range ofρ(Li_(2)B_(4)O_(7))=3~15 g/L,the conductivity of the electrolyte continued to increase,and the roughness of the ceramic layer continued to increase overall,which only slightly decreased when the electrolyte concentration changed from 6 g/L to 9 g/L.The thickness of micro-arc oxidation ceramic layer first continuously decreased in the range ofρ(Li_(2)B_(4)O_(7))=3~9 g/L and then increased in the range ofρ(Li_(2)B_(4)O_(7))=9~15 g/L.The hardness of the ceramic layer first decreased in the range ofρ(Li_(2)B_(4)O_(7))=3~6 g/L,and then increased in the range ofρ(Li_(2)B_(4)O_(7))=6~15 g/L.In addition,the ceramic layers were all composed of monoclinic zirconia(m-ZrO_(2)).As the concentration of Li_(2)B_(4)O_(7) in the electrolyte increased,the porosity of the ceramic layer decreased and the micropore size changed little.The friction coefficient of the ceramic layer increased continuously in the range ofρ(Li_(2)B_(4)O_(7))=3~12 g/L,and decreased whenρ(Li_(2)B_(4)O_(7))=15 g/L.By comprehensive comparison,the ceramic layer with moderate thickness,good hardness,smooth and continuous surface,small porosity and pore size,good wear resistance and corrosion resistance could be obtained in the electrolyte withρ(Li_(2)B_(4)O_(7))=15 g/L.