| Summary: | 碩士 === 國立臺北科技大學 === 材料及資源工程系研究所 === 102 === Pulsed bipolar power was used for MAO coating on titanium substrate. An aqueous solution containing K2SO4、NaOH and Na2WO4 was used as electrolyte. Different compositions used for MAO on titanium were investigated in this work.
The XRD pattern obtained from the surface of the MAO coated specimen shows that the coating consist of anatase and rutile. As we can see in the SEM image, the surface became porous when we add more K2SO4、NaOH and Na2WO4. We think that the surface become more and more porous which causing by ions react violently. It is the reason why that the surface morphology will get porous. When bubbles come out from the ceramic oxide film, it makes the film become porous. The bubbles will also make the current unstable. When current have been disrupted, we can discover the sparking on the surface. In the same time, we can observe the impact ionzation and tunneling ionization between each electrons in the electrolytes. When the andodic voltage keep rising, we can see the micro arc on the surface. According to the wear test, we obtain the optimum electrolyte parameters which are 5% K2SO4 7% Na2WO4 、3% K2SO4 3% Na2WO4 and 5% K2SO4 3% Na2WO4 3% NaOH this three parameters. Therefore, we obtain the porosity film on the pure titanium surface which can protect the substrate.
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