铝合金微弧氧化正向电流与膜层形成的关系  

Relation between forward current and coatings formation on aluminum alloy in micro-arc oxidation process

作　　者：刘彩文[1,2] 刘向东[1,2] 吴士军[3] 

机构地区：[1]内蒙古工业大学材料科学与工程学院,内蒙古呼和浩特010051 [2]内蒙古自治区材料成型及控制工程重点实验室,内蒙古呼和浩特010051 [3]呼和浩特职业学院生物化学工程学院,内蒙古呼和浩特010070

出　　处：《材料热处理学报》2013年第7期159-164,共6页Transactions of Materials and Heat Treatment

基　　金：内蒙古自治区自然科学基金项目(2013MS0812);内蒙古工业大学重点研究项目(ZD201214)

摘　　要：在含Na2SiO310 g/L、NaOH 2 g/L、Na2WO42 g/L、Na2EDTA 2 g/L和C3H8O3 10 mL/L的电解液和正/负向电压取440/130 V的条件下对铝合金(ZL108)进行微弧氧化处理。利用涡流测厚仪、XRD、光学显微镜和SEM对获得膜层进行表征。通过观察微正向电流变化分析膜层的形成过程。研究发现,在电压达到预设值前,试样表面只形成了局部的氧化膜,对电流的影响不显著。氧化2 min到12 min之间,膜层快速增长,最大值达8.75μm/min,膜层仅含γ-Al2O3相,膜层表面氧化物颗粒数目及尺寸均增加。膜层向内外同时生长。但膜层较为疏松易被溶解,由于膜层沉积-溶解交替进行引起电流在8 A和6 A之间波动。氧化12 min到35 min之间,膜层缓慢增长,最小值达0.5μm/min,膜层以向内生长为主。膜层中3Al2O3.2SiO2和γ-Al2O3相的含量有减少的趋势,而α-Al2O3相和SiO2相在增加。氧化膜经过高温相变与烧结生成致密的陶瓷膜。陶瓷颗粒由椭球形转变成圆球形。膜层增厚变密导致电流由6 A持续下降到2 A。氧化到53 min时,立刻息弧,膜层停止生长。微弧氧化正向电流的变化间接地反映了氧化膜的形成。Coatings on aluminum alloy were obtained at 480 V forward voltage and 130 V reverse voltage in an electrolyte containing 10 g/L Na2SiO3,1 g/L NaOH,2 g/L Na2WO4,2 g/L Na2EDTA and 10 ml/L C3H8O3 by micro-arc oxidation.Thickness of coatings was measured.The phases and morphology of coatings were analyzed by XRD,optical microscope and SEM.The results show that the process of micro-arc oxidation for aluminum alloy（ZL108） can be divided into four steps in accordance with the change of forward current,i.e.ascending,fluctuating,descending and extingction of arc stages.It is the ascending stage when the current is ascending along with the forward voltage ascending,no successive coatings formed.Subsequently,the current fluctuates with coatings deposition-dissolution departure balance and film characteristic remarkablly changes.When the current fluctuates between 8 A and 6 A within 10 min,successive and loose oxidation coatings appear.The formation rate increases to 8.75 μm/min.The coatings grow towards inside and outside simultaneously,and the content of γ-Al2O3 phase rises.The number and the dimension of ceramic particles are increasing.When the current declines from 6 A to 2 A（from 12 to 38 min）,the formation rate decreases to 0.5 μm/min.The shape of ceramic grain almost changes from elliptical sphere to spherical sphere.The coatings grow mainly towards substrate.The content of 3Al2O3·2SiO2 and γ-Al2O3 decreases while the content of α-Al2O3 and SiO2 phases increases.In this stage,the current descending is determined by the proportion of compact layer increasing.In the extinguishing arc stage（from 38 to 53 min）,the thickness of coatings ceases increasing.The variety of forward current reflects the process of micro-arc oxidation coatings formation indirectly.

关 键 词：ZL108铝合金 微弧氧化 正向电流 膜层形成 

分 类 号：TG174.4[金属学及工艺—金属表面处理]