Does anyone know whether pure zirconium is resistant to corrosion by 68% nitric acid at 430°C?
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Our company uses pure zirconium for the equipment; the corrosive medium is 68% concentrated nitric acid at a temperature of 430°C, and the zirconium material gets corroded. I wonder whether pure zirconium itself is not suitable for such an environment
This post was last edited by sifangok on 2017-2-9 at 14:40. No relevant data could be found; the highest temperature reported as usable is 250°C. It seems you will need to conduct experiments on your own. The material that best meets these conditions, according to available information, is silicon-containing alloys
This post was last edited by sifangok on 2017-2-9 at 14:37. There’s a thread in the forum titled “The Most Comprehensive List (3): Nitric Acid,” which contains detailed data that you might want to take a look at. Additionally, search for articles on the current applications and future prospects of industrial-grade zirconium in the chemical industry; those articles state that the maximum temperature is 260°C, so 430°C is way too high – it doesn’t make any sense at all
At this temperature, it should be high pressure, right?
NB/T 47011-2011 states that nitric acid can withstand temperatures of 210°C at a concentration of less than 95%
This temperature is that of the steam heating tube, right? It might be advisable to increase the heat exchange area in order to reduce the steam pressure. Furthermore, zirconium is not a panacea either; from what I remember, only the zirconia formed on the surface of the equipment can resist most types of corrosion. Corrosion resistance data for such temperatures may not be available in the relevant manuals, so it is necessary to conduct corrosion tests oneself. Also, if there are defects in the welded areas, it can lead to corrosion of the equipment
With such high temperatures and strong acids, careful selection of materials is necessary. Use tantalum material.
Tantalum materials probably cannot be used at such high temperatures either; 430 is too high
According to the available data, under conditions of a nitric acid concentration of 70% and a temperature of 120°C, the corrosion resistance rating is grade A; this rating is no longer applicable. The boiling point of nitric acid according to the SDS is 122°C. Based on similar data, titanium seems to be a better choice (corrosion rate of 1.1–1.2 MM/year at temperatures of 270–290°C)