J4不锈钢及化学镀Ni-P和Ni-Cu-P镀层在液-固两相流中的冲刷腐蚀行为

用质量损失法系统研究了不同温度(25和50℃)和不同冲刷速率(0.63—1.88 m/s)下,J4不锈钢、Ni-P和Ni-Cu-P合金镀层,及对比材料316L不锈钢在液-固两相流(20%H_2SO_4+20 g/L Al_2O_3)中的冲刷腐蚀行为,结果表明:不锈钢和镀层的抗冲刷腐蚀性能由高到低依次为镀态Ni-Cu-P,镀态Ni-P,热处理态Ni-Cu P,316 L,J4,提高两相流介质温度均使它们的冲刷腐蚀速率增大。316L不锈钢在25℃液-固两相流介质中的冲刷腐蚀速率分别为镀态Ni-Cu P,镀态Ni-P和热处理态Ni-Cu-P镀层的8.5倍,8倍和2.6倍以上,而在50℃下分别为392倍,80倍和14.8倍以上;J4不锈钢在25和50℃液-固两相流介质中的冲刷腐蚀速率分别为316L不锈钢的28倍和13倍以上,在25和50℃,J4不锈钢分别为选择性腐蚀和均匀腐蚀,而316L不锈钢均为轻微选择性腐蚀,Ni-P和Ni-Cu-P合金镀层均为均匀腐蚀。     

Experimental study on the prevention of microbial fouling accumulation on a Ni-Cu-P modified heat exchange surface

Microbial fouling on heat exchange surface is common for large amount of microorganisms in circulating cooling water. In this article, a modified surface technology is used to suppress and reduce the accumulation of microbial fouling on the heat transfer surface. Firstly a Ni-Cu-P modified surface is prepared by electroless plating, and a Ni-P surface applied commonly in industry is also prepared as a comparison. With the help of the designed and constructed experimental system for dynamic monitoring of microbial fouling, the microbial fouling tests of the Ni-Cu-P, Ni- P and carbon steel surface are carried out. The results show that the Ni-Cu-P modified surface has excellent antifouling performance. Compared with carbon steel, the microbial fouling on the Ni-P and Ni-Cu-P modified surface are decreased by 90.6 % and 92.0 % respectively. Further the effects of temperature, flow rate, and initial bacterial concentration on microbial fouling heat resistance of Ni-Cu-P modified surface are investigated and analyzed. With the cooling water inlet temperature increasing (25–40 °C), the fouling heat resistance of the Ni-Cu-P modified surface is increased first and then reduced. With the flow rate increasing (0.2 m/s-0.3 m/s), the fouling heat resistance of Ni-Cu-P modified surface is decreased by 78.3 %. With the initial bacteria concentration in cooling water increasing (8.364 × 10⁹ CFU/mL −51.456 × 10⁹ CFU/mL), the fouling heat resistance is increased by 57.4 % accordingly. By rationally adjusting the operating conditions, such as regulating the temperature of cooling water far away from the suitable temperature of bacteria and increasing the flow rate of circulating cooling water as much as possible, the accumulation of microbial fouling on the Ni-Cu-P modified surface can be further reduced, allowing for long-term cleaning and effective heat transfer of the Ni-Cu-P modified heat exchange surface.