Sodium hydroxide, also known as caustic soda, is an important industrial product. It has a wide range of uses. It is a strong alkali. It does not corrode seriously at room temperature, but it will cause serious corrosion to many metals in the presence of high temperature and stress. Iron and steel can be used in dilute sodium hydroxide solution at room temperature, but it will corrode rapidly when the temperature or concentration increases. It is important to study the corrosivity of different alloys in sodium hydroxide solution for material selection.

　　2. 氢氧化钠选材的依据

　　NaOH 是一种强碱，在常温下腐蚀性不强，但在高温和有应力存在的情况下会对许多金属产生严重腐蚀[1]。不同浓度的NaOH 溶液在不同温度下其设备和管道的选材如图１和表１所示。从图１和表１可以看出，氢氧化钠溶液的浓度为0～30％，若温度低于50℃的情况下，Ⅰ类材质的设备和管道通常是耐腐蚀的；而0％～30％氢氧化钠溶液在Ⅱ类材质的设备及管道中，在温度为50～100℃的情况下，耐腐蚀性能较好。

　　It is a kind of strong alkali. It is not very corrosive at room temperature, but it will cause serious corrosion to many metals at high temperature and in the presence of stress. The material selection of equipment and pipes for different concentration solutions at different temperatures is shown in Fig. 1 and Table 11. From Fig. 1 and Table 1, it can be seen that the concentration of NaOH solution is 0-30%. If the temperature is lower than 50 C, the equipment and pipes of Class I material are usually corrosion-resistant, while the corrosion resistance of 0%-30% NaOH solution is better in the equipment and pipes of Class II material at the temperature of 50-100 C.

　　从选材图1和表1还可以看出，，银对NaOH 的耐蚀性好，其次是镍。银和镍能耐所有浓度和温度的NaOH，直到熔融状态（480℃）。对于高温、高浓度碱而言，好选用镍及其合金（如因科镍，蒙乃尔等）。不锈钢对40％～50％以下的NaOH溶液可耐温80～100℃，但不耐高浓度、高温碱液。碳钢在较稀的低温NaOH溶液中耐腐蚀性能较好，可以在表面形成坚实的氧化保护膜，且由于低廉，常常成为许多用户的。

　　It can also be seen from the material selection figures 1 and 1 that the corrosion resistance of silver pairs is the best, followed by nickel. Silver and nickel can withstand all concentrations and temperatures until they melt (480 C). For high temperature and high concentration alkali, nickel and its alloys (such as Inco nickel, Monel, etc.) are the best choice. Stainless steel can withstand 80-100 C for solutions below 40%-50%, but not high concentration and high temperature alkali solution. Carbon steel has good corrosion resistance in relatively low temperature NaOH solution and can form a solid oxide protective film on the surface. Because of its low cost, it is often the first choice of many users.

　　以上内容由氢氧化钾厂家整理发布，更多相关信息可以点击我们的官网进行咨询：http://www.jinhao360.com

　　The above content is organized and published by potassium hydroxide manufacturers. More information can be consulted by clicking on our official website: http://www.jinhao360.com.