含铍碳化硅陶瓷先驱体聚铍碳硅烷的合成

Synthesis of Precursor of SiC ceramic containing beryllium

以氢氧化铍、硫酸和乙酰丙酮为原料合成了乙酰丙酮铍(Be(acac)2)。用乙酰丙酮铍和聚碳硅烷在加热的条件下反应一定时间,生成了树脂状的产物。反应中乙酰丙酮铍被消耗,生成产物熔点相对起始聚碳硅烷熔点升高。元素分析表明产物中含有铍元素,凝胶渗透色谱分析表明产物分子量相对起始聚碳硅烷向增大的方向发生变化。傅立叶红外光谱分析表明产物中主要存在如下结构:Si(CH3)2—CH2—,—Si(CH3).(H)—CH2—。核磁共振1 H-NMR分析表明反应物中Si—H键被消耗。根据分析结果推测了反应机理,Si—H键的消耗在产物的形成中起了重要作用。实验与理论分析表明先驱体产物是一种含铍聚碳硅烷,可以命名为聚铍碳硅烷(PBeCS)。在1200℃的高温处理下产物作为先驱体可以转化为碳化硅陶瓷,元素分析表明碳化硅陶瓷中含有铍,是含铍碳化硅陶瓷。

Beryllium acetylacetonate [Be(acac)2] was synthesized using beryllium hydroxide,sulfuric acid and acetylacetone as raw material.Beryllium acetylacetonate [Be(acac)2] reacted with polycarbosilane(PCS) with heating,resionoid product was produced.In the reaction,the beryllium acetylacetonate was consumed,the melting point was rised comparing to the onset polycarbosilane.The element analysis shows there are some beryllium in the product,the gel permeation chromatography GPC ana-lysis shows the molecular of the product rised comparing to the onset polycarbosilane.Fourier transform infrared spectroscopy(FT-IR) analysis shows there are such chemical structures in PBeCS: Si(CH3)2—CH2—,—Si(CH3)·(H)—CH2—.1H-NMR shows the Si—H bond in the reagent was consumed.The reaction mechanism is inferred on the basis of analysis result,and the Si—H bond played a crucial role in the formation of the product.The experiment and theory analysis shows the product is a kind of polycarbosilane containing beryllium,which can be called polyberylliumocarbosilane(PBeCS).After treated under 1200℃ the product PBeCS can be converted into the silicon carbide containing Beryllium.