目的 探索可实现微观结构精准调控,绿色环保、低成本、高效的催化剂载体制备技术,推动微弧氧化技术在催化剂载体领域的广泛应用,提升微弧氧化陶瓷层的吸水性能。方法 在恒流模式下,通过控制微弧氧化负向电流的数值在ZL109铝合金基体表面制备得到陶瓷层。通过电源系统导出的电压数据、扫描电子显微镜、能谱仪、X射线衍射仪、光学轮廓仪研究了微弧氧化反应过程和微弧氧化陶瓷层的微观形貌、厚度、孔隙率和平均孔径、表面粗糙度、化学组成及物相组成等特征指标。通过GSAS Ⅱ软件对X射线衍射数据的精修结果得到了陶瓷层主要物相组成的相对含量。最后根据国家标准GB_T 25994-2010和GB_T3810.3-2006对陶瓷层试样进行了吸水性能测试。结果 微弧氧化负向电流的数值对陶瓷层吸水性能具有显著的影响。在本实验条件下,负向电流3 A制备的陶瓷层吸水率达11.7%。结论 在一定范围内,负向电流和负向电压的升高有利于陶瓷层致密性的提高;当负向电流达到一定值,正向电压对微弧氧化反应的影响逐渐提升,在无显著致密相生成的同时会提高陶瓷层的孔隙率,从而有利于陶瓷层的吸水性能;但当负向电流进一步增加,反应能量达到一定值时,陶瓷层中致密相（莫来石和α-Al₂O₃）的含量增加,导致陶瓷层孔隙率降低,进而陶瓷层吸水性能下降。

Gas treatment technology is an important component of Chinese environmental protection industry, energy industry, chemical industry, high-end equipment manufacturing industry, strategic emerging industries, and green and low-carbon industries. Catalyst carriers are the core components of gas purification treatment devices, which can enhance the efficiency and stability of gas purification treatment devices by dispersing active components, increasing mechanical strength, and optimizing mass and heat transfer. Honeycomb ceramics are widely used as catalyst carriers in gas purification treatment due to their large specific surface area, low gas resistance, good chemical stability, low thermal expansion coefficient, and good thermal shock resistance. The development of gas purification treatment technology has put forward higher requirements for catalyst carrier materials in terms of efficiency, economy, environmental friendliness, and durability.
Traditional methods for preparing honeycomb ceramics mainly include extrusion molding, hot-pressing casting, and slip casting. However, these methods have problems such as difficulty in precisely controlling multi-scale defects, complex processes, and environmental pollution in actual production. Moreover, advanced preparation technologies are mainly monopolized by countries like the United States and Japan. To overcome these limitations, various new honeycomb ceramic preparation technologies have emerged in recent years, such as additive manufacturing, freeze casting, and gel casting. However, these technologies are usually limited by mold shapes, high production costs, and complex processes, making them difficult to apply in large-scale production. Therefore, developing catalyst carrier preparation technologies that can precisely control multi-scale defects and are environmentally friendly, low-cost and efficient has become an urgent need.
Micro-arc oxidation (MAO), also known as liquid-phase plasma electrolytic oxidation (PEO), is a surface treatment technology developed on the basis of conventional anodic oxidation. As a green and environmentally friendly technology, micro-arc oxidation has significant advantages such as non-polluting electrolyte composition, simple process, and no need for strict surface pretreatment. Through complex electrochemical, plasma chemical, and thermochemical reactions, micro-arc oxidation can form ceramic coatings on the surfaces of metals such as aluminum, magnesium, and titanium and their alloys. The resulting ceramic coatings have high hardness, excellent wear resistance, corrosion resistance, thermal shock resistance, and extremely low thermal expansion coefficients. More importantly, the microstructure of the ceramic layer can be controlled by regulating the micro-arc oxidation reaction process. Therefore, some scholars have utilized the micro-arc oxidation technology on aluminum alloy surfaces to prepare a new type of catalyst carrier, achieving reliable loading of the catalyst through the micro-porous structure of the micro-arc oxidation ceramic layer.
Previous studies on the micro-arc oxidation technology of ZL109 surface have generally focused on the improvement of anti-friction and wear resistance performance, and there is a lack of research results on the water absorption performance of the micro-arc oxidation ceramic layer. Therefore, this work focuses on the water absorption performance of the micro-arc oxidation ceramic layer of ZL109 aluminum alloy. In the pre-experiment of this work, the effects of electrical parameters such as forward current, reverse current, power supply frequency, and duty cycle on the water absorption performance of the ceramic layer were systematically studied. Through range analysis, it was found that the reverse current had a more significant impact on the water absorption performance of the ceramic layer. Therefore, the effect of reverse current on the water absorption performance of the micro-arc oxidation ceramic layer of ZL109 aluminum alloy was mainly analyzed.
To explore catalyst carrier preparation technologies with precise control on microstructure and characterized by environmentally friendly features, low cost, and efficiency, promote the wide application of micro-arc oxidation technology in the field of catalyst carriers, and improve the water absorption performance of micro-arc oxidation ceramic layers, ceramic layers were prepared on the surface of ZL109 aluminum alloy substrates by controlling the negative current value in the constant current mode. The microstructure, porosity and average pore size, surface roughness, chemical composition, and phase composition of the micro-arc oxidation ceramic layers were studied by analyzing the voltage data from the power supply system through scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and optical profilometry. The relative content of the main phase composition of the ceramic layers was obtained by refining the X-ray diffraction data with GSAS Ⅱ software. Finally, the water absorption performance of the ceramic layer samples was tested according to the national standards GB_T 25994-2010 and GB_T3810.3-2006. The negative current value had a significant impact on the water absorption performance of the ceramic layer. Under the experimental conditions of this study, the ceramic layer prepared with a negative current of 3 A had a higher water absorption rate (11.7%). The specific conclusions are as follows:
(1) Under the constant current mode, the negative voltage and positive voltage of the micro-arc oxidation reaction on the surface of aluminum alloy show different trends. Under the condition of constant positive and negative currents, with the extension of reaction time, the positive voltage gradually increases, while the negative voltage rises to a certain value and remains basically stable. As the negative current increases, the stable value of the negative voltage gradually increases and under the condition of constant positive current, the value of the positive voltage also gradually increases.
(2) The negative voltage and positive voltage of micro-arc oxidation have a coupled effect on the film-forming state of the ceramic layer on the surface of aluminum alloy. Within a certain range, the increase of negative current and negative voltage is conducive to the improvement of the density of the ceramic layer. When the negative current reaches a certain value, the effect of the positive voltage on the micro-arc oxidation reaction gradually increases, which will increase the porosity of the ceramic layer without significantly generating dense phases, thereby improving the water absorption performance of the ceramic layer, but when the negative current further increases and the reaction energy reaches a certain value, the content of dense phases (mullite and α-Al₂O₃) in the ceramic layer increases, resulting in a decrease in the porosity of the ceramic layer and a subsequent decline in the water absorption performance of the ceramic layer.