臺灣博碩士論文加值系統

本研究在探討退火條件對陽極處理膜及其電解著色膜物性之影響，期望利用退火處理之優點，獲得更良好的氧化鋁膜，以利於進行電解著色，並尋求最佳黑色電解著色操作條件。將退火後之純鋁試片在硫酸溶液中進行陽極處理及在硝酸銀溶液中進行電解著色，藉由微硬度、膜厚及色差的測量，並且配合SEM之觀察及EDS分析存在的化學元素，來瞭解退火之影響。
實驗結果發現，經過一定溫度和時間下退火處理，由於表面結晶組織重新排列，可改善氧化膜的生長情形。在退火後所產生的結晶相，由X-ray繞射分析得知為γ-Al2O3，此外，由SEM可觀察到，退火後之鋁片，其孔洞結構較大，因此所產生的氧化鋁膜會影響在硝酸銀溶液中電解著色。使用色差計測量，可測得最低的L值為10.32，而在可見光波長範圍下測試下，可得最低反射度值為5.54%之黑色陽極氧化膜。
為了在鋁片上得到最佳的黑色膜，其最佳的操作條件如下：退火溫度 500 ℃及退火時間2hr，陽極電流密度 2 A/dm2，浴溫20 ℃。

This research is to investigate the effect of the annealing conditions on the physical properties of the anodic oxide film and colored film. It is expected that by taking the advantages of annealing, a better aluminum oxide layer can be obtained to proceed the electrolytic coloring for getting a black film. By the way, to find the optimum operation conditions to obtain the darkest shade of black anodic film on aluminum. Specimen of the annealed aluminum was investigated after anodizing in sulfuric acid solution and then electrolytic coloring in silver nitrate solution. The microstructure, microhardness, thickness, chromatism and chemistry elements of anodic oxide film were studied by using scanning electron microscopy (SEM), microhardness tester, electronic thickness tester, spectrophotometer and energy dispersive spectroscopy (EDS).
It is found that after the annealing treatment at given temperature and time, because of the rearrangement of the surface crystalline structure, the growth condition of the anodic film can be improved. From the analysis of X-ray diffraction and the observation of SEM, it is known that the crystalline produced after the annealing is γ-Al2O3, and the structures of the pores are larger. Therefore, the anodic oxide film from annealing would be helpful for the electrolytic coloring in the silver nitrate solution, hence the lowest L-value of 10.32 and the minimum reflectivity of 5.54 % were obtained.
To obtain the better black film on aluminum, the best operating conditions are as follows: annealing temperature of 500 ℃ for 2hr, anodic current density of 2 A/dm2 at bath temperature of 20 ℃.

TABLE OF CONTENTS

ACKNOWLEDGEMENTS…………………………………………………………………i
ABSTRACT……………………………………………………………………………ii
ABSTRACT IN CHINESE…………………………………………………………iv
TABLE OF CONTENTS………………………………………………………………v
LIST OF TABLES…………………………………………………………………ix
LIST OF FIGURES…………………………………………………………………x
CHAPTER 1 INTRODUCTION………………………………………………………1
CHAPTER 2 BACKGROUND OF THEORIES………………………………………5
2.1 Pretreatment of Aluminum………………………………………5
2.1.1 Strong Alkaline Cleaning………………………………………5
2.1.2 Weak Acid Cleaning………………………………………………5
2.1.3 Deionized Water Rinsing………………………………………6
2.2 Annealing……………………………………………………………6
2.3 Anodic Oxidation of Aluminum…………………………………8
2.3.1 Microstructure of Anodic Oxide Film………………………10
2.3.2 Mechanism of Anodic Oxidation………………………………14
2.3.3 Solution of Anodizing Treatment……………………………17
2.3.4 Pulsed Current Method…………………………………………18
2.4 Electrolytic Coloring…………………………………………22
2.4.1 The Cause of Coloring on the Porous Oxide Film………22
2.4.2 Mechanism of Electrolytic Coloring………………………23
CHAPTER 3 EXPERIMENTS……………………………………………………28
3.1 Materials and Specimens Preparation……………………28
3.1.1 The Pretreatment before Annealing………………………28
3.1.2 Annealing………………………………………………………29
3.1.3 The Pretreatment before Anodic Oxidation………………29
3.1.4 Anodic Oxidation………………………………………………29
3.1.5 Electrolytic Coloring………………………………………30
3.1.6 Film Dissolution Test………………………………………30
3.2 Apparatus………………………………………………………31
3.2.1 Power Supply and Rectifier…………………………………31
3.2.2 Agitator…………………………………………………………31
3.2.3 Thermobath and Cooling Pump…………………………………31
3.2.4 Digital Multi-meter……………………………………………32
3.2.5 Annealing Furnace………………………………………………32
3.3 Procedures………………………………………………………35
3.3.1 Pretreatment Process…………………………………………35
3.3.2 Annealing Process………………………………………………36
3.3.3 Pretreatment Process…………………………………………36
3.3.4 Anodizing Process………………………………………………36
3.3.5 Electrolytic Coloring Process………………………………37
3.3.6 Dissolution Process ……………………………………………37
3.4 Measurements………………………………………………………38
3.4.1 Film Thickness……………………………………………………38
3.4.2 Film Hardness………………………………………………………38
3.4.3 Test of Dissolution Characteristics…………………………41
3.4.4 Calculation of Coating Ratio…………………………………41
3.4.5 X-ray Diffraction…………………………………………………41
3.4.6 SEM Observation……………………………………………………42
3.4.7 EDS Test………………………………………………………………42
3.4.8 Reflectance (%) Test………………………………………………42
3.4.9 Color Difference of Colored Coatings…………………………43
CHAPTER 4 RESULTS AND DISCUSSION……………………………………………46
4.1 The Formation of Porous Aluminum………………………………46
4.1.1 The Formation Voltage of Porous Aluminum……………………46
4.1.2 The Influence of Anodizing on Microhardness…………………47
4.2 Process Optimization of Electrolytic Coloring ………………51
4.2.1 The Effect of Annealing Temperature……………………………51
4.2.2 The Effect of Annealing Time……………………………………55
4.2.3 Influence of Electrolytic Coloring Time………………………57
4.3 The X-ray of Diffraction of The Film……………………………62
4.4 The Observation of SEM………………………………………………65
4.5 The EDS of The Film……………………….…………………………68
4.6 The Effect of Annealing on Reflectivity of Colored Film……70
4.7 Results of the Film Dissolution Test……………………………76
4.7.1 The Effect of Film Dissolution……………………………………76
4.7.2 The Effect of Film Density…………………………………………77
4.7.3 Coating Ratio…………………………………………………………77
CHAPTER 5 CONCLUSIONS……………………………………………………………81
REFERENCE……………………………………………………………………………83

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