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采用化学镀的方法,调整Ni-P化学镀工艺参数,获得了磷含量不同的镀层,具有非晶、纳米晶及二者混合的微观结构。进一步的凝结传热实验结果表明,高磷非晶镀层表面具有明显促进珠状凝结的效果,在凝结过程中表现为珠膜共存状态,而碳钢管表面仅出现膜状冷凝。同时,换热表面经Ni-P镀层改性后,可以获得较好的传热性能。镀层对换热性能的改善与镀层中非晶的含量相关,表现为,随着非晶含量的增加,换热效率得到增强。对于非晶镀层换热表面,在特定的冷却水流量下,提高蒸汽温度可以促进珠状冷凝效果的产生。
The electroless plating method was used to adjust the parameters of electroless Ni-P electroless plating. The coatings with different phosphorus contents were obtained, and the microstructures of amorphous, nanocrystalline and their mixture were obtained. The results of condensation and heat transfer experiments show that the surface of high-phosphorus amorphous coating has the obvious effect of promoting the formation of bead condensation, while the appearance of coexistence of bead film during the condensation process, while only the film-like condensation occurs on the surface of carbon steel pipe. At the same time, the heat transfer surface by Ni-P coating modified, you can get better heat transfer performance. The improvement of the heat transfer performance of the coating is related to the amorphous content in the coating, which shows that as the amorphous content increases, the heat transfer efficiency is enhanced. For the amorphous coating heat exchange surface, at a specific cooling water flow, increasing the steam temperature can promote the formation of bead-like condensation.