Abstract

Anodic aluminum oxide (AAO) film with a thickness ranging from 20 to 100 μm was prepared using a large-sized Al plate (4 cm × 10 cm) to investigate the anodization parameter effect on the film thickness and volume expansion factor. A corrosion treatment (voltage = 0 V) was performed to investigate the film dissolution caused by acid. The actual anode surface temperature was also measured to confirm the field-assisted nature of AAO dissolution. The film thickness increases exponentially with temperature, and increases approximately linearly with voltage, duration or concentration. The volume expansion factor gives a first rising and then falling trend with temperature or duration, while it has a nearly linear trend with voltage or concentration. The volume expansion factor increases with the intensified electric field, while its decrease is attributed to the Joule heat-enhanced dissolution. In the case of large film thickness (> 20 μm), the pore confinement effect may be one of the reasons for the change of volume expansion factor. In addition to the conventional parameters, the heat transfer-related parameters (for example, sample size) also greatly affect the AAO film growth.

Highlights

  • In the past decade, due to thinner wall thickness, higher thermal conductivity and stronger mechanical strength, metallic-monolith catalyst (MMC) support made of stainless steel or FeCrAl is considered as a potential alternative to the conventional cordierite monolithic catalyst support [1,2]

  • Anodic aluminum oxide (AAO) film with a thickness ranging from 20 to100 μm was prepared by using a large-sized Al plate (4 cm × 10 cm) to investigate the anodization parameter effect on the film thickness and volume expansion factor

  • The volume expansion factor increases with the intensified electric field, while its decrease is attributed to the Joule heat-enhanced dissolution

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Summary

Introduction

Due to thinner wall thickness, higher thermal conductivity and stronger mechanical strength, metallic-monolith catalyst (MMC) support made of stainless steel or FeCrAl is considered as a potential alternative to the conventional cordierite monolithic catalyst support [1,2]. The combination of pore widening treatment (immersing in acid solution) and hydrothermal treatment could convert amorphous skeleton alumina into γ-alumina and change its smooth and parallel tube-like pore structure into a two-dimensional pore structure with a larger specific surface area This present work focuses on investigating the influence of anodization conditions on the film thickness and volume expansion factor of the AAO film, with the goal of achieving highly-controlled AAO film growth. The influence of the preparation parameters on the thickness and volume expansion is investigated by varying the anodization conditions (voltage, duration, temperature and concentration), in order to find the interaction between these anodization parameters and determine controllable parameters for preparing AAO film into catalyst support

Experimental
Effect of anodization voltage and duration on AAO film thickness
Effect of anodization voltage and duration on volume expansion factor
Conclusions
Full Text
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