電漿熔射高介電性Al2O3/TiO2塗層之研究

Abstract

本實驗研究目的在於獲得一高介電常數之陶瓷塗層，其主要應用範圍在於靜電夾持的設備上。靜電夾持的基本構造包括一電極層與一介電層，若要擁有足夠的靜電夾持力量，則此介電層材料必須擁有高介電常數、高介電強度與高絕緣電阻值的特性。 本實驗利用電漿熔射來噴附Al2O3、Al2O3+3%TiO2、Al2O3+13%TiO2、Al2O3+40%TiO2四種不同陶瓷粉末於6061鋁合金基材上。實驗結果發現四種陶瓷塗層之鍵結強度皆在5595~8505 psi之間，並且發現Al2O3+TiO2之塗層比純Al2O3之塗層可以擁有更緻密的塗層。經過高溫電漿熔射後，原本棕色之Al2O3/TiO2混合粉末變成藍黑色的塗層，此藍黑色塗層為具導電性質之材料，因此Al2O3+13%TiO2、Al2O3+40%TiO2便成為導體。至於Al2O3+3%TiO2因只有少量的藍黑色成分生成，所以影響較小，且其擁有較佳之緻密度，所以其崩潰電壓較純Al2O3高19.8%、介電常數高16.9%。至於在高溫環境下Al2O3+3%TiO2崩潰電壓的表現還是較佳，不過因為Ti+的不穩定，所以其崩潰電壓隨著溫度的升高而有較明顯的下降趨勢。 電漿熔射後使用雷射重熔來降低塗層多孔隙之缺點。因陶瓷塗層與基材的熱傳導係數、熱膨脹係數相差過大，造成裂縫的產生。另外預熱溫度不夠高，所以無法有效降低孔隙率。若使用不□鋼作為基材，將可以減少裂縫的產生，並可以提高預熱溫度來降低孔隙率。

The purpose of the research is to obtain ceramic coating with higher dielectric constant. The major application is used in the equipment of electrics static chuck (ESC). Basic structure of ESC includes an electrode layer and a dielectric layer. In order to have enough chuck strength, the dielectric material must have high dielectric constant, high dielectric strength and high electric resistance. Four coating powders including Al2O3、Al2O3+3%TiO2、Al2O3+ 13%TiO2、Al2O3+40%TiO2 were employed on the substrate of Alloy 6061. The result of this experiment shows that the bound stresses of four coatings are between 5595 psi and 8505 psi. The density of Al2O3+TiO2 coating is higher then that of Al2O3. Using high temperature plasma-spray, the brown Al2O3+TiO2 powder becomes blue-black coating. This blue- black coating is a conductive material. Therefore, both Al2O3+13%TiO2 and Al2O3+40%TiO2 become conductive. Since Al2O3+3%TiO2 only has fewer blue-black components, the influence of conductive is small. Since Al2O3+3%TiO2 has a higher density, the breakdown is higher than that of pure Al2O3 about 19.8% and dielectric constant is higher than that of pure Al2O3 about 16.9%. In the high temperature condition, Al2O3+3%TiO2 has greater value of breakdown. Because of the instability of Ti+, the tendency of breakdown decreases clearly. After plasma-spraying, laser remelting was used to reduce defect of porosity. Because the ceramic coating and base metal have different thermal conductive constant and thermal expansion constant, cracks were occurred. Because the preheat temperature has not been enough, the porosity can’t be reduced effectively. Therefore, if stainless steel is chose as the base metal, a higher preheat temperature is needed to reduce porosity.