Phase and microstructure of CVD alumina-silica coating deposited at relative low temperature

À´Ô´ÆÚ¿¯£ºÖйúÓÐÉ«½ðÊôѧ±¨(Ó¢ÎÄ°æ)2005ÄêµÚz3ÆÚ

ÂÛÎÄ×÷Õߣº³ÂÕÕ·å ÕÔ±£ÈÙ ÖìÐãÈÙ Ñϲ¨ Àî´Ï

ÎÄÕÂÒ³Â룺402 - 406

Key words£ºalumina-silica composite coating£» phase£» microstructure£» CVD£» low temperature

Abstract: Alumina-silica composite coatings were prepared on the surface of graphite paper by CVD using AlCl₃/SiCl₄/H₂/CO₂ as precursor in the temperature range of 300 to 550¤@¡æ. XRD and SEM were used to examine the phase composition and the microstructure of the coating, respectively. The results indicate that the dense, uniform and adherent alumina-silica composite coating can be prepared on graphite paper substrate by CVD at 550¤@¡æ using SiCl₄/AlCl₃/CO₂/H₂. The alumina-silica composite coating is composed of a number of spherical particles. Each particle is composed of a number of fine-particle. The phase of the 550¤@¡æ composite coating includes ¦Ã-alumina containing amorphous silica. The content of Cl element in composite coating decreases with the increase of the deposition temperature. The analysis results of morphology and growth mechanisms of the CVD alumina-silica indicate that the condensation within the boundary layer will be more likely to lead to the formation of gel-particles. The gel-particles size decreases with the increase of deposition temperature in the range of 300550¤@¡æ. Surface reaction is the main path to generate deposition products at 550¤@¡æ.