A novel pretreatment strategy for accurate determination the Al element content within polyaluminumcarbsilane

Abstract

Polymer-derived silicon carbide (SiC) fibers show their merits of high-temperature resistance, oxidation resistance and corrosion resistance; and introducing certain amounts of hetero-elements into ceramic precursor could improve the properties of SiC fibers. Therefore, it is very important to accurately control the amount of introduced hetero-elements to optimize the functionalization of the target SiC fibers. The current method of hetero-element content determination in precursors is to directly adopt the method of hetero-element content in amorphous or microcrystalline ceramics. In contrast to ceramics, low molecule weight Al-contained precursors are easy to volatilize during the alkali fusion process. Moreover, the precursor digestion solution is more likely to produce silicic acid flocculent precipitation when the solution is treated after alkali fusion. These two main aspects seriously affect the detection accuracy of hetero-element content in precursors. In this work, taking polyaluminumcarbsilane (PACS), which is one of the most commonly used ceramic precursors, as a subject of research; and the effects of pretreatment conditions for accurate determination the Al element content within are investigated. The pretreatment method of air crosslinking for precursor, as well as pH value adjustment of digestion solution, is proposed; enabling the accurate detection of Al in PACS. The optimized pretreatment conditions are reached for obtaining the Al elements contents accordant with theoretical derived ones, showing that this method is accurate and reliable. This pretreatment strategy could be extended to other kinds of hetero-elements within precursors.