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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ommendations include directly fogging the VCI oil additive into the preserved system at a specified dosage per volume of the oil system. The amount of VCI additive inside the system will affect the partitioning of the corrosion inhibitor into the aqueous phase. Several ratios of oil phase to water were examined to investigate the parti- tioning behavior of the corrosion inhibitor. At recommended dosages of 3 to 5%, the partitioning effect of the corrosion inhibi- tor from the VCI additive will be evaluated with the neat additive and with the addi- tive dosed as recommended by the manu- facturer. The ratio of oil phase to aqueous phase was varied as well, investigating 1:1 and 9:1 ratios of oil to water. Extraction of Corrosion Inhibitor A solution of 5% VCI oil additive in standard synthetic poly alpha olefin oil was created. Along with the concentrated oil additive, Table 1 shows the solutions made. Oil solutions were added to a large beaker and deionized (DI) water was gently poured through the oil layer until the desired oil to water ratio was achieved. Each beaker was covered and allowed to sit for 24 h. After the 24-h period, the oil layer was decanted and separated using a separatory funnel. The remaining aqueous phase was collected, labeled, and submitted for analysis. A sample of the DI water was also submitted for testing to ensure no base level of organic nitrogen is present in the solvent. Because the volume of water ingress in a preserved system would generally be low com- pared to the volume of the treated oil, Sample No. 4 is considered the most representative of a real-life preservation system. For preserved systems when the VCI oil additive is fogged and water ingress is experienced, Sample No. 1 could be considered the most representative test sample for the system. Determination of Corrosion Inhibi- tor Concentration The primary corrosion inhibitor com- ponent identified in the VCI oil additive is an organic nitrogen-based corrosion inhib- itor compound . Aqueous samples were sent to a third-party analytical laboratory for analysis using the Kjeldahl Method for determining organic nitrogen content in aqueous solutions. Immersion Corrosion Testing Two sets of immersion corrosion test- ing were performed as part of this evalu- ation. The first evaluation was performed with no duplicates and pan el cleaning was performed with 1% hydrochloric acid (HCl), 1% commercial acid corrosion inhib- itor, and 98% DI water mixture. The second evaluation was performed in triplicate and panel cleaning was performed with a stan- dard ASTM G01 7 solution. Immersion Corrosion Testing— First Iteration Testing was performed in DI water, with var ying amounts of the corrosion inhibitor identified above from the VCI oil additive in solution. The solution was held in a cylindrical glass cell with a 5-in (127- mm) height and 2-in (50.8-mm) diameter. Two hundred g of each solution were used in each test cell to ensure full immersion of the tested panels (0.63 by 1 by 3-in [16 by 25.4 by 76.2-mm] SAE 1008/1010 cold- rolled steel). Panels were prepared by hand polishing both faces to a consistent finish with 240 grit aluminum oxide (Al 2 O 3 ) abra- sive paper. Panels were cleaned with meth- anol, 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 removed, rinsed with metha- nol, and oxides were removed from the sur- face via a 1% concentrated HCl solution, also containing 1% corrosion inhibitor to prevent f lash corrosion during the clean- ing process. The panels were examined for mass loss and the rate of corrosion was cal- culated using the following formula from ASTM G31 (Equation [2], Section 12.4): 3.45×10 6 ×W A×T×D Corrosion Rate (mpy) = (1) W represents the mass loss in grams, A is the panel surface area in cm 2 , T is the duration of the test in hours, and D is the metal density in grams per cubic centimeter (7.87 g/cm 3 for SAE 1008/1010 steel). The corrosion rate reduction was also calculated by comparing the control sample to the test samples with the following formula: Corrosion Rate Reduction = 1− ×100% ( ) (2) where C represents the corrosion rate of the control sample and R is the corrosion rate of the test sample. A single panel was prepared for each tested solution, along with a single panel to be tested in DI water as a control. A single prepared, but untested, steel panel was sub- jected to the cleaning procedure as above. 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. Immersion Corrosion Testing— Second Iteration Testing was performed in DI water, with varying amounts of the corrosion inhibi- tor identified above from the VCI oil addi- tive in solution. The solution was held in a cylindrical glass cell with a 5-in height and 2-in diameter. Two hundred g of each solu- tion was used in each test cell to ensure full immersion of the tested panels (0.63 by 1 by 3-in SAE 1008/1010 cold-rolled steel). Pan- els were prepared by hand polishing both faces to a consistent finish with 240 grit TABLE 1 Sample Identification for VCI Oil Additive Extraction Sample No. VCI Oil Additive Concentration (%) Oil to Water Ratio Ratio of VCI Additive to Water 1 100 1:1 1:1 2 100 9:1 9:1 3 5 1:1 0.05:1 4 5 9:1 0.45:1 19 CORTEC SUPPLEMENT TO MP MATERIALS PERFORMANCE JUNE 2019

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