Influence of Pulse Frequency on the Structure and Oxidation Resistance of AlPO<sub>4</sub> Ceramics Coating and its Deposition Dynamics

A facile pulse arc discharge deposition method was developed to prepare AlPO 4 oxidation resistant outer coating on SiC pre-coated carbon/carbon composites (SiC-C/C). The deposition dynamics and the influence of pulse frequency on composition, microstructure and oxidation resistance of the as-prepared coating were investigated. Results show that pulse arc discharge deposition is an effective route to achieve dense and crack-free AlPO 4 coatings. The deposition activation energy of the AlPO 4 coating is calculated to be 3.07 kJ·mol -1 . The AlPO 4 coating prepared at a pulse frequency of 2000 Hz exhibits good oxidation resistance, which can effectively protect C/C composites from oxidation in air at 1773 K for 262 h with a weight loss of 1.58%.