镀镍碳纳米管添加剂作用下的负向电压对ZL109铝合金微弧氧化陶瓷层的制备及耐磨性能影响

Effects of Negative Voltage on the Preparation and Wear Resistance of ZL109 Aluminum Alloy Micro-arc Oxidation Ceramic Layers under the Action of Nickel-coated Carbon Nanotubes Additive

目的 提高铸造铝合金关键零部件的可靠性和耐用性,推动微弧氧化表面处理技术的发展,探索新型微弧氧化磁性纳米粒子电解液添加剂作用下的电源电压对微弧氧化陶瓷层的影响。方法 采用单因素控制法,设置微弧氧化电源负向电压为100、110、120、130、140、150、160V,向电解液体系中引入0.8g/L镀镍碳纳米管添加剂,利用扫描电子显微镜、光学轮廓仪、X射线光电子能谱、X射线衍射及自制的往复式摩擦磨损试验机等,对制备得到的微弧氧化陶瓷层的微观形貌、厚度、表面粗糙度、致密性、孔隙率、孔径及耐磨性能进行分析,主要研究镀镍碳纳米管添加剂作用下的微弧氧化电源负向电压对ZL109铝合金微弧氧化陶瓷层的制备及耐磨性能的影响。结果 负向电压140 V制备得到的陶瓷层致密性好,表面粗糙度Ra为0.77μm,表面孔隙率为2.05%,平均孔径为0.594μm,且具备一定的厚度(11.5μm)和较好的耐磨性能(磨损量为0.13 mg)。结论 镀镍碳纳米管添加剂与电源正、负电压对微弧氧化反应过程存在着协同作用关系;负向电压对微弧氧化反应过程、陶瓷层的微观形貌、厚度、致密性、表面粗糙度等影响显著。

In order to further improve the reliability and durability of key cast aluminum alloy parts,promote the development of micro-arc oxidation surface treatment technology,and explore the influence of positive and negative voltage of power supply with new micro-arc oxidation magnetic nanoparticles electrolyte additives on micro-arc oxidation ceramic layers.In this work,single factor control method is adopted,the negative voltage of micro-arc oxidation power supply is set as:100 V,110 V,120 V,130 V,140 V,150 V,160 V,and 0.8 g/L nickel-plated carbon nanotubes additive is introduced into the electrolyte system,the micro-arc oxidation ceramic layers are analyzed by scanning electron microscope,optical profilometer,X-ray photoelectron spectroscopy,X-ray diffraction and a self-made reciprocating friction and wear testing machine in terms of micro morphology,thickness,surface roughness,compactness,porosity and pore size analysis and wear resistance property,the effects of negative voltage of micro-arc oxidation power supply on the preparation and wear resistance of ZL109 aluminum alloy micro-arc oxidation ceramic layers are analyzed.In this paper,the micro-arc oxidation ceramic layers are prepared by a bipolar pulsed micro arc oxidation power supply.On the basis of the previous research results,the positive voltage varying by stages is good for preparing composite coatings.Therefore,in this work,the positive voltage of power supply is controlled manually in three stages:360 V for 1-5 min,400 V for 6-10 min,440 V for 11-15 min.The total reaction time was 15 min.The composition of the electrolyte is:4 g/L Na2SiO3,4 g/L Na2WO3,2 g/L KOH and 2 g/L EDTA-2Na.When the negative voltage is less than 110 V,large deep holes are unevenly distributed on the surface of the ceramic layers.When the negative voltage reaches 120 V,the porosity of the ceramic layers increases obviously,and relatively small deep pores are evenly distributed on the surface.However,when the negative voltage reaches 130 V and above,the surface of the ceramic layers is replaced by a large number of shallow pores with relatively uniform distribution.The main elements of the prepared ceramic layers are oxygen,aluminum,silicon and carbon,and the main phases areα-Al2O3 andγ-Al2O3.In the reciprocating friction and wear tests,the ceramic layer prepared with negative voltage of 100 V shows overall wear on the surface,and the wear resistance of the ceramic layer is relatively poor,and the actual contact area of the friction pair is increased,so the friction coefficient is high.The friction coefficient of ceramic layers obtained by other negative voltages basically remained at about 0.4,among which,the friction coefficient of ceramic layer prepared by negative voltages 140 V is low,with small fluctuation and low wear.The wear surface morphology shows that the ceramic layer is only slightly worn locally,and the ceramic layer can basically keep the original surface morphology.The ceramic layer prepared with negative voltage 140 V has good compactness,low surface roughness(Ra,0.77μm),the surface porosity is 2.05%,the average pore size is 0.594μm,a certain thickness(11.5μm)and good wear resistance(The wear loss is 0.13 mg).The results show that there is a synergistic relationship between nickel-coated carbon nanotubes and the positive and negative voltage of the power supply on the micro-arc oxidation reaction,the negative voltage has a significant effect on the micro-arc oxidation reaction process,the micro morphology,thickness,compactness and surface roughness of the ceramic layers.