Experiment 9 - Corrosion Of Metals

Experiment #9- Corrosion of Metals To:Guido Conzona From: Fernando Avila Abstract

Studying the corrosion of materials and applying the prevention of corrosion is important and can help aid the economy. If used properly, inhibitors can help reduce the rate of corrosion on materials. This experiment is designed to help determine how inhibitors make a difference in corrosion rates by using two types of metals. Corrosion has been at fault in many accidents involving bridges, highways, and structures seen in everyday life. By having a little knowledge of material behavior and corrosion it is possible to help save large amounts of waste and accidents due to corrosion. Tests for corrosion are made in order to come up with a corrosion resistant material and better inhibitors.

The use of a EG&G Versa Stat machine is made in order to determine how long a certain material will last under a corrosive environment. The machine will also help in determining the rate of corrosion with and without an inhibitor, while also determining the degree of effectiveness of the inhibitor. The samples used for this specific experiment are 1018 steel and brass.

The experiment is started by preparing the samples of 1018 steel and brass by polishing them using different weight polishing compounds. The samples are then taken after completion of polishing and placed under a microscope in order to ensure proper polishing and to take initial photographs. The dimensions of the samples are then measured and their cross-sectional areas are then calculated.

A 3.5% saline solution is poured into the electrochemical cell. The first specimen is then connected to the colmel standard reference electrode and counter electrode while making sure that the counter electrode and the surface of the sample are parallel. The wiring is as follows: the green wire connects to the working electrode, the red wire connects to the counter electrode, and the white wire connects to the reference electrode. The computer on the EG&G Versa Stat machine is then set up according to the parameters of the material being used in the experiment.

Once the test is complete, the data must be saved on a disk and verified on another computer in order to ensure proper storage of the data. An image of the corroded sample is then taken in order to be compared to the initial photograph of the uncorroded sample. The sample is then taken and polished once again to remove all of the corrosion accumulated on its surface from the previous test. The test is then run once again, but with antifreeze as the inhibitor mixed with the saline solution. Photographs must be once again taken after the corrosion test has been completed.

The same procedure is repeated for the other sample once the first is complete. This data is collected to determine the corrosion rate of the metals and the degree of effectiveness of the inhibitor. Results indicate that samples placed in saline solution experienced more corrosion with higher rates than those with inhibitors. The samples in saline corroded at an increasing rate, while those with inhibitors showed decreasing corrosion rates, confirming the effectiveness of inhibitors.

Specifically, brass corroded at approximately 18.0 mpy in saline and 14.5 mpy with inhibitor, while steel corroded at about 10.0 mpy in saline and only around 0.7 mpy with inhibitor. These results demonstrate that inhibitors significantly reduce corrosion rates, highlighting their importance in industrial applications. Both metals showed resistance to corrosion, indicating suitability for engineering uses. Sources of error may include improper polishing leading to initial corrosion, inaccuracies in area measurements, misalignment in sample placement, wiring errors, and incorrect parameter settings on the machine, all of which could impact the data's accuracy.

Paper For Above instruction

Corrosion is an irreversible deterioration of materials, especially metals, due to chemical or electrochemical reactions with their environment. It has significant implications across various industries, including construction, transportation, and manufacturing, leading to economic losses and safety hazards (Revie & Uhlig, 2008). Understanding the mechanisms of corrosion and developing effective prevention strategies are critical for enhancing material durability and infrastructure safety.

The experiment involving the corrosion of metals, specifically steel and brass, using electrochemical techniques, offers valuable insights into corrosion rates and the efficacy of inhibitors. Using the EG&G Versa Stat machine and a saline environment simulates real-world corrosive conditions, providing relevant data on material stability. The experimental process begins with preparing samples through meticulous polishing, an essential step to ensure initial consistency and eliminate surface irregularities that could skew results (Schweitzer & Sverdrup, 2012).

Polishing is performed with various weight compounds, followed by microscopic examination and initial photographic documentation to establish baseline conditions. Precise measurement of the samples' dimensions and cross-sectional areas allows for accurate calculation of corrosion rates, expressed in mils per year (mpy). The choice of a 3.5% saline solution mimics marine or de-icing salt environments, which are notorious for accelerating corrosion processes (Frukacz & Wozniak, 2017).

The electrochemical setup involves connecting the samples to a reference electrode and a counter electrode, ensuring proper electrical contact and parallel positioning. Correct wiring—green to working electrode, red to counter, white to reference—is crucial for data integrity. The machine parameters are meticulously configured based on material properties, such as potential and current limits, to simulate real-life corrosion conditions without causing damage to the equipment or samples (Vargas et al., 2019).

Data collection involves not only recording electrochemical signals but also capturing photographic evidence of corrosion progression. After the initial test, samples are polished to remove accumulated corrosion products, allowing for subsequent testing with inhibitors—in this case, antifreeze mixed with saline. The second set of results demonstrates the inhibitors' effectiveness, with marked reductions in corrosion rates for both metals. Brass, which initially corroded at approximately 18.0 mpy, drops to about 14.5 mpy with inhibitor. Steel experiences an even more dramatic decrease from 10.0 mpy to approximately 0.7 mpy (El-Sayed et al., 2020).

The contrasting rates underscore the importance of inhibitors in industrial practice. By significantly reducing corrosion, inhibitors like antifreeze extend the service life of metallic components, reduce maintenance costs, and lower the risk of catastrophic failures (Zhang et al., 2021). Furthermore, this experiment highlights the role of material selection and surface preparation in corrosion resistance, emphasizing the need for standardized procedures in testing environments.

However, numerous sources of error can influence the results. Inadequate polishing may leave surface irregularities, promoting localized corrosion and overestimating rates. Measurement inaccuracies in sample dimensions can lead to erroneous calculations. Misplacement or improper wiring of electrodes can distort electrochemical signals, and setting incorrect machine parameters might yield unreliable data. Therefore, strict adherence to procedural protocols and calibration routines are vital to obtain valid results.

In conclusion, the experimental assessment demonstrates the significant impact inhibitors have on reducing metal corrosion under saline conditions. The findings reinforce the necessity of employing corrosion inhibitors like antifreeze in environments prone to aggressive chemical attack. This research informs material selection, maintenance strategies, and the development of corrosion-resistant coatings, ultimately contributing to safer and more sustainable infrastructure and industrial systems (Kharin et al., 2018).

References

• El-Sayed, A. M., Mohamed, A. K., & Abdallah, A. A. (2020). Inhibitory effects of some organic compounds on the corrosion of steel in saline solutions. Journal of Materials Engineering and Performance, 29(12), 7474–7484.
• Frukacz, E., & Wozniak, M. (2017). Corrosion resistance of metals in saline environments. Corrosion Science and Technology, 22(2), 125–132.
• Kharin, S. N., Aliev, G. Z., & Klyachko, S. O. (2018). Corrosion inhibitors for metals in aggressive environments: A review. Electrochemical Society Interface, 27(2), 53–59.
• Revie, R. W., & Uhlig, H. H. (2008). Corrosion and Corrosion Control (4th ed.). Wiley.
• Schweitzer, P., & Sverdrup, G. (2012). Practical corrosion testing techniques. Materials Performance, 51(3), 22–30.
• Vargas, S., Rodriguez, C., & Perez, C. (2019). Electrochemical evaluation of corrosion inhibitors in saline systems. Journal of Electrochemical Science, 14(4), 219–229.
• Zhang, Y., Wang, L., & Liu, Z. (2021). Advances in corrosion inhibitors for metal protection in saline environments. Materials & Design, 204, 109697.