Materials Performance Supplements

CORTEC 2019

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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VOLATILE CORROSION INHIBITORS Al 2 O 3 abrasive paper. Panels were cleaned with methanol, weighed to the nearest 0.1 mg, and placed into the respective solutions. Test cells were placed into a 40 ± 2 °C oven for approximately three weeks. At this time, panels were rinsed with methanol, wiped clean with a lint-free wipe, and placed in a cleaning solution as specified in ASTM G01, designation C.3.5 (500 mL HCl, 3.5 g hexam- ethylene tetramine, and reagent water to make 1,000 mL solution). Panels were then dipped into a solution of commercial corro- sion inhibitor at 1% in DI water and dried with a lint-free wipe to prevent further flash corrosion prior to examination of mass loss. The panels were examined for mass loss and the rate of corrosion was calculated as noted in Equation (1). Three panels were prepared for each tested solution, along with three panels to be tested in DI water as a control. A single prepared, but untested, steel panel was prepared and subjected to the cleaning procedure. The mass loss of the cleaning procedure was determined, and this mass loss was subtracted from the mass loss measured in each tested panel, in order to determine the true mass loss from the immersion corrosion testing. Electrochemical Corrosion Testing EIS was performed on several solutions with different concentrations of the corro- sion inhibitor identified above in DI water with 300 ppm sodium chloride (NaCl). EIS testing was performed with 10 mV ampli- tude around open circuit potential (OCP) over a frequency range of 0.01 to 100,000 Hz on a C1018 steel plug and modeled using the Randles equivalent circuit. The inhibi- tor efficiency was calculated by comparing the polarization resistance (R P ) of the con- trol against the experimental polarization resistance (Equation [3]). Inhibitor Efficiency = 1− ×100% ( ) Control R p Experimental R p (3) Extraction of Corrosion Inhibitor from VCI Oil Additive Extracted solvent samples were submit- ted for analysis of organic nitrogen content according to the Kjeldahl Method. Results were received in ppm of organic nitrogen in the sample. The amount of corrosion inhib- itor (in ppm) was calculated based on the ratio of nitrogen in the corrosion inhibitor molecule (Table 2). As the ratio of VCI additive to water increased, the concentration of corrosion inhibitor increased in kind. As shown in Figure 1, the inhibitor partitioning seemed to plat eau at high VC I additive ratios. Based on the results, a wide range of cor- rosion inhibitor concentrations were eval- uated in immersion testing to observe the effect of varying concentrations on inhibi- tor on the corrosion protection efficiency. TABLE 2 Corrosion Inhibitor Content Results Sample No. Ratio of VCI Additive to Water Inhibitor Detected (ppm) 1 1:1 1,368 2 9:1 2,234 3 0.05:1 535 4 0.45:1 802 TABLE 3 Concentration of Corrosion Inhibitor in Tested Solutions Sample Label Inhibitor Concentration (% by weight) Inhibitor Concentration (ppm) Control 0 0 A 0.5 5,000 B 0.2 2,000 C 0.1 1,000 D 0.08 800 E 0.05 500 FIGURE 1 Corrosion inhibitor concentration compared to the ratio of VCI oil additive to water from extraction testing. 20 JUNE 2019 MATERIALS PERFORMANCE CORTEC SUPPLEMENT TO MP

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