Earticle

Recently anodizing technique for titanium metal products becomes of more keen interest because of the titanium’s own nature. Anodizing technique has provided such possibility, but up to now the color obtained reveals somehow primary color. In this paper, we proposed a compound process, i.e. at first chemical oxidization, then followed by further anodizing process, so that the colors between primary colors have been successfully obtained. In addition we tried the color analysis for the specimen obtained both by ordinary and our anodizing techniques using a colorimeter. Finally, we present examples of titanium piece fabricated, adopting a freehand drawing technique

本研究は,チタン金属の着色の方法である陽極酸方法を発展させ、化学酸化方法と組み合わせた発色方法として試みたものである。チタンに関しては、単に防食技術の発展だけでなく､金属表面に塗料とは異なる色彩あるいは光沢などを付加させ､プロダクトデザイン上からも一般の民生市場に新たな金属製品の用途を持たせるようになって来た。さらに光触媒としてチタン金属に全く新規な機能を付加させられることも分かってきた。チタンを様々なデザイン分野に導入するための色彩付加の技術は重要な技術である。最近では製品にカラーバリエションを増やしてヒット商品になった例が多く報告されている。金属材料にカラフルな着色ができるのは以前と較べて、様々なデザイン分野の用途に広げてきた。従来の陽極酸化法で発色した色は大別して57色、細分して99色である。色彩は全般的に色鮮やかで原色に近い色が多い。そのためにカラーコーディネイトする際の色彩バランスに欠けるところがあった。したがって本研究は従来の陽極酸化で発色できた色をさらに増やすために、特に様々な中間色を発色できるようにした。従来の陽極酸化法に比べて、化学酸化と組み合わせた陽極酸化法では赤－緑および黄－青色に関する鮮やかな原色と異なり、中間色に近い淡い色味の色彩が得られる。色に関しては、原色も中間色のどちらも色彩デザイン上に必要なので、従来方法と黒下塗り方法を組み合わせていくことが必要である。発色方法としては黒色を得るために実施されてきた化学酸化法で一旦形成した黒色層を消去し、引き続いて陽極酸化法を実施して興味ある色彩、すなわち、より中間色に近い色相や低明度、低彩度の色が得られることができた。この研究では一定程度に黒色を脱色するかが重要である。また、この研究では目視による色彩判定だけでなく色彩測定器で測色し定量的な比較を行った。また、その結果をデ－タベ－ス化した。これまでも裸眼による作業者などの経験的な判断に評価が委ねられていたが、測色デ－タの蓄積と分析によって再現性のある色が可能になると期待される。

Anodization of die-casted AZ91D magnesium alloy was carried out using silicate based electrolyte solution instead of fluoride based solution to improve biocompatibility of oxidized layers. The anodic layer obtained from silicate based solution has smaller size of pore and smoother surface, resulting in lower corrosion rate in simulate body solution (SBF). Effect of enhanced structural and chemical properties in oxidized layer on biocompatibility was carefully considered.

Aluminum alloy is a material that is frequently used in the aerospace and transportation industries due to its high mechanical and corrosion resistance qualities. Unfortunately, aluminum alloys are prone to corrosion, limiting their application in some harsh situations such as when submerged in aqueous environments. The purpose of this study is to investigate how anodizing can increase the corrosion resistance of 6061 Aluminum alloy. The anodizing process was carried out using two different parameters which are voltage (5V, 10V, 15V) and electrolyte sulfuric acid (H₂SO₄) concentration (0.3M, 0.5M) for 1 hour. The anodized samples were performed using several analyses such as X-ray diffraction (XRD) analysis, morphology analysis, and corrosion test. From this study, it is found that the difference in anodizing parameters affects the corrosion resistance of the samples. Sample anodized at 15V, 0.5M gives the best corrosion resistance.

A simple method for the fabrication of porous nano-master for the anti-reflection effect on the transparent substrates is presented. In the conventional fabrication methods for antireflective surface, coating method using materials with low refractive index has usually been used. However, it is required to have a high cost and long processing time for mass production. In this paper, we developed a porous nano-master with anti-reflective surface for the molding stamper of the injection mold, hot embossing and UV imprinting by using the aluminum anodizing process. Through two-step anodizing and etching processes, a porous nano-master with anti-reflective surface was fabricated at the large area. Pattern size Pore diameter and inter-pore distance are about 130nm and 200nm, respectively. In order to replicate anti-reflective structure, hot embossing process was performed by varying the processing parameters such as temperature, pressure and embossing time etc. Finally, antireflective surface can be successfully obtained after etching process to remove selectively silicon layer of AAO master.

High efficiency LED device is being concerned due to its high heat loss, and such heat loss will cause a shorter lifespan and lower efficiency. Since there is a demand for the materials that can release heat quickly into the external air, the organic insulating layer was required to be replaced with high thermal conductive materials such as metal or ceramics. Through anodizing the upper layer of Al, the Breakdown Voltage of 3kV was obtained by using an uniform thickness of $60{\mu}M$ aluminum oxide($Al_2O_3$) and was carried out to determine the optimum process conditions when thermal cracking does not occur. Two Ni layers were formed above the layer of $Al_2O_3$ by sputtering deposition and electroplating process, and saccharin was added for the purpose of minimizing the remain stress in electroplating process. The results presented that the 3-layer film including the Ni layer has an adhesive force of 10N and the thermal conductivity for heat dissipation is achieved by 150W/mK level, and leads to improvement about 7 times or above in thermal conductivity, as opposed to the organic insulation layer.

Airplane reservoirs made of Al7075 are coated with an anodizing layer to maintain precision, air tightness and corrosion resistance. It is commonly required that the inner surface roughness of the reservoir be less than an average $0.2{\mu}m$ to maintain stable oil pressure. Even though precision polishing is necessary to achieve this quality it is not easy. Inner surface roughness is not uniform and the quality of the product is irregular because most of the work is done by hand. The purpose of this study is to design an exclusive polishing machine and to determine the standard cutting condition and polishing condition necessary for good inner surface roughness and to improve workefficiency.