致密热解碳层的混合气体包覆工艺研究

Study on coating technology of gas mixture for dense pyrolytic carbon layer

致密热解碳层是高温气冷堆包覆燃料颗粒的关键组成。该文介绍了在流化床包覆炉中采用丙烯（Ｃ３Ｈ６）和乙炔（Ｃ２Ｈ２）的混合气体作为反应体系的包覆工艺，以消除只用丙烯作为包覆气体时产生的热效应。讨论了包覆工艺参数（沉积温度、乙炔浓度等）对致密热解碳层的密度、沉积速率和碳利用率的影响，确定了制备致密热解碳层的最佳工艺条件。研究的结果在生产规模流化床包覆炉中得到了验证和实际应用。

Dense pyrolytic carbon layer (PYC) is the key component of the composite coating of TRISO coated fuel particle in high temperature gas cooled reactor. This paper describes that the coating technology of using a gas mixture of propylene (C 3H 6) and acetylene (C 2H 2) in fluidized bed coating furnace was developed in order to eliminate the thermal effects of propylene decomposition. The influence of coating process parameters (deposition temperature, acetylene concentration) on coating density, deposition rate and deposition efficience are discussed. The optimum coating conditions have been obtained. The dense PYC layers fulfilling the design specification has been fabricated in a fluidized bed coating furnace.