A case study of vapor phase corrosion inhibitor fo

Case study on vapor phase corrosion inhibitor for metal packaging (Part 2)

II. Experimental results

1. vapor phase rapid screening test

determine the best pH value of phytic acid as a vapor phase corrosion inhibitor by gas phase rapid screening test with different pH values after adding ammonia to phytic acid solution. When 1g phytic acid is dissolved in 10ml of water, its pH value is 1.15, which is very acidic. When ammonia is added, the color of the solution changes from light yellow to dark brown, accompanied by exothermic phenomenon. This indicates that a chemical reaction has taken place to produce phytic acid ammonia salt. When phytic acid is used as a corrosion inhibitor for VCI paper, pitting corrosion occurs within 24 hours under natural conditions; When the pH value was adjusted to 7 with ammonia water, pitting corrosion occurred within 96 hours. When the pH value is 9, it has good vapor phase corrosion inhibition performance in the test cycle. Therefore, when phytic acid is used as a vapor phase corrosion inhibitor, the pH value can be adjusted to about 9 with ammonia water to give full play to its good vapor phase corrosion inhibition performance. This shows that the ammoniated phytic acid has strong vapor phase corrosion inhibition performance

2. corrosion weight loss test

the purpose of corrosion weight loss test is to study the relationship between coating amount and weight loss rate. According to the results of the gas phase rapid discrimination test, the pH value of phytic acid solution was adjusted to about 9 with ammonia, and the corrosion weight loss test was carried out. The hydraulic pump can be started. It is concluded that phytic acid is a dangerous vapor phase antirust packaging paper inhibitor. When the coating amount is less than 15g/m2 or more than 30g/m2, pitting corrosion occurs within 24 hours. The vapor phase inhibition effect is poor and the weight loss rate is large. Therefore, when phytic acid is used as corrosion inhibitor for VCI paper, the coating amount should be controlled between 15-30g/m2

3. evaporation reduction test in confined space

in the evaporation reduction test in confined space, the weight loss rate of phytic acid was larger than that of dicyclohexylamine nitrate. The experimental data show that the saturated vapor pressure of phytic acid in confined space is higher than that of dicyclohexylamine nitrate. Therefore, when phytic acid is used as a vapor phase rust inhibitor, it can quickly volatilize and fill the packaging space, adsorb to the metal surface, and thus play a role in corrosion inhibition

4. corrosion inhibition performance test

corrosion loss this kind of phenomenon in China's extruder industry is due to the poor performance of individual ICs or components, which is beneficial for export. The purpose of many tests is to study the relationship between coating amount and weight loss rate. According to the results of the gas phase rapid discrimination test, the pH value of phytic acid solution was adjusted to about 9 with ammonia, and the corrosion weight loss test was carried out. According to the results of gas phase rapid screening test, when the coating amount is 20g/m2, xudianli, executive vice president and senior engineer of China Refractory Industry Association, introduced that the performance of phytic acid on A3 steel is stronger than that of dicyclohexylamine nitrate. At the same time, phytic acid also has good vapor phase corrosion inhibition performance for tin and zinc plating materials

from the test results, it can be determined that phytic acid, as a corrosion inhibitor for anti rust packaging paper, has good moisture and heat resistance and can be used in high temperature and high humidity environment

III. conclusion

1. when phytic acid is used as vapor phase corrosion inhibitor, the pH value must be adjusted to about 9 with ammonia water in order to give better play to its vapor phase corrosion inhibitor performance

2. phytic acid is a kind of high-efficiency gas-phase corrosion inhibitor, which has stronger corrosion inhibition than dicyclohexylamine nitrate. At the same time, phytic acid also has good vapor phase corrosion inhibition performance for non-ferrous metals such as tinned steel plate and galvanized steel plate. It is a multifunctional vapor phase corrosion inhibitor

3. in high temperature and high humidity environment, non-toxic phytic acid has good vapor phase corrosion inhibition performance for ferrous metals, tinned steel plates and galvanized steel plates

4. phytic acid is an ideal substitute for nitrite corrosion inhibitor

(compiled by yangwenliang)

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