lab report

Experiment #9- Corrosion of Metals

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.

Description of Work:

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 it’s 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 must be repeated for the other sample once the first in complete. This data is to be collected to determine the corrosion rate of the metals and degree of effectiveness of the inhibitor.

Results:

Based on the data collected it is apparent that the samples placed in the saline solution had much more corrosion and had corroded at a higher rate than the samples with the inhibitor. The samples in the saline solution corroded at an increasing rate, while the samples in the saline solution with an inhibitor corroded at a decreasing rate, showing how the inhibitor proved useful. The brass corroded at at rate of approximately 18.0mpy in the saline solution and at approximately 14.5mpy in the solution with an inhibitor. The steel sample corroded at a rate of approximately 10.0mpy in the saline solution, and at a rate of approximately 0.7 mpy in the solution with the inhibitor. As one can see from these results, it is made apparent that the use of an inhibitor is extremely important in reducing rates of corrosion. Both of the samples used proved to have good resistance to corrosion signifying a good use in industry. The sources of error in this experiment could have come been attributed to many factors. Some being as follows: There could have been under-polished samples that had initial corrosion that attributed to an increase in corrosion rate, the area measurements used in the calibration of the machine could have been incorrect, the position of the sample in the solution could have been incorrect, The wiring could have been incorrect, and the Parameters set on the computer could have been incorrect leading to incorrect readings.