Hello everyone,
In order to investigate the degradation behaviour , magnesium alloys were immersed in Hank's solution for 24 hours. Corroded sections of magnesium alloys contained salts and corrosion products. ultra -sonication with ethanol and acetone did not work either for removal of these products.
Thanks,
Khurram
Hi, for determining the weight loss of Mg / Mg alloys after immersion tests, the removal of corrosion products with 180 g/L chromic acid (at room temperature, for about 30 min) is quite common.
There are two solutions listed in ASTM G1 for removing corrosion products from Mg Alloys. Both of them contain chromic acid:
Solution #1 - 150 g CrO3 +10 g Ag2CrO4 in 1L DI water
Conditions #1 - Boiling for 1 minute
Solution #2 - 200 g CrO3 + 10 g AgNO3 +20 g Ba2(NO3)2 in 1 L DI water
Conditions #2 - 20-25 degrees C for 1 minute
I have not cleaned Mg alloys, but one of the ASTM cleaning solutions recommended for stainless steel is 150 g of diammonium citrate in 1 L of water at 70 degrees C for 10-60 minutes. A second one used for lead alloys that you could try is ammonium acetate at 250 g / L at 60 - 70 degrees C for 5 minutes. I would recommend trying these on a very small scale before moving to larger pieces since I am not sure of reactivity. I am just trying to give other potential options for you to try.
As you said alternative to chromic ACID, I would suggest below in accordance with ISO 8407:2009 –still contains chromium trioxide but not chromic acid.
200 g of chromium trioxide (CrO3)
10 g of silver nitrate (AgNO3)
20 g of barium nitrate [Ba(NO3)2]
Distilled water to make 1 000 ml
for 1 min at 20-25 Celsius.
The silver salt is presented to precipitate chloride. The barium salt is presented to precipitate sulfate.
Siqi Yin : Hi could you please give me the condition to prepare the CrO3+AgNO3 solution? Thank you very much.
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