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Surgical implants: Pitting corrosion Potential Measurements of Stainless Steel
Source：Corrtest
Time：2021-12-24
View：0
Surgical implants: Pitting corrosion Potential Measurements of Stainless Steel
1. Instrument and accessories
CS350 potentiostat galvanostat
CS930 4-neck cell (500mL), Luggin capillary, CS900 saturated calomel electrode, CS911 platinum plate counter electrode, thermostat water bath
Solution and others: pure NaCl, pure KCl, distilled water, powered agar, 703 silicon rubber
2. Preparation before testing
2.1 Salt-bridge preparation
Prepare 1~1.5g powered agar,10g KCl and 30ml instilled water to a beaker. Heat the beaker on the asbestos gauze to 80℃. During heating, stir the solution using a glass rod till all the solid is dissolved and minimize the air bubbles. As soon as finishing heating, immerse the tip of luggin capillary into the agar solution, and suck agar at a constant rate into the luggin capillary using the rubber suction bulb (please don’t let air in during this process). Then pour the agar solution from the upper port of the luggin capillary till middle of the thick part. Before the agar gets cold, insert the SCE into the agar. When the agar gets cold, add some saturated KCl solution.
2.2 Sample preparation
Surgical implant stainless steel sample should have been under deactivation treatment.
The sample should be suitable in size, and easy to clamp and stabilize. If the sample is too small, you should weld the wire onto the sample.
If the sample is too big, you should choose a piece after sawing or cutting. The plate sample should be rolling plane. For rod sample, you should choose the drawing surface.
The surface of the sample should be treated with alcohol, acetone, and after drying out, seal the sample with the 703 silicon rubber(or epoxy resin) to make the exposure area to be 1cm2.
2.3 Solution
Add 4.5g pure NaCl into the 4 neck cell containing 500mL instilled water to make the 9g/L NaCl solution. Put the cell into thermostat water bath to keep temperature 37±1℃.
3. Experiment Steps
Put the sample, salt bridge and Platinum plate electrode into the thermostat 4-neck cell. The distance between the tip of the salt bridge and the sample’s center should be 1~2mm. The green clamp(WE) connects to the sample, the yellow clamp(RE) connects to SCE, and the red clamp(CE) connects to the platinum plate electrode..png)
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. You should wait a while till the system is stable.
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For every batch of product, you should choose three parallel samples.
4. Results
In the main menu, please click Tools for data analysis. Click following icon to import the data file for analyzing..png)
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1. Instrument and accessories
CS350 potentiostat galvanostat
CS930 4-neck cell (500mL), Luggin capillary, CS900 saturated calomel electrode, CS911 platinum plate counter electrode, thermostat water bath
Solution and others: pure NaCl, pure KCl, distilled water, powered agar, 703 silicon rubber
2. Preparation before testing
2.1 Salt-bridge preparation
Prepare 1~1.5g powered agar,10g KCl and 30ml instilled water to a beaker. Heat the beaker on the asbestos gauze to 80℃. During heating, stir the solution using a glass rod till all the solid is dissolved and minimize the air bubbles. As soon as finishing heating, immerse the tip of luggin capillary into the agar solution, and suck agar at a constant rate into the luggin capillary using the rubber suction bulb (please don’t let air in during this process). Then pour the agar solution from the upper port of the luggin capillary till middle of the thick part. Before the agar gets cold, insert the SCE into the agar. When the agar gets cold, add some saturated KCl solution.
2.2 Sample preparation
Surgical implant stainless steel sample should have been under deactivation treatment.
The sample should be suitable in size, and easy to clamp and stabilize. If the sample is too small, you should weld the wire onto the sample.
If the sample is too big, you should choose a piece after sawing or cutting. The plate sample should be rolling plane. For rod sample, you should choose the drawing surface.
The surface of the sample should be treated with alcohol, acetone, and after drying out, seal the sample with the 703 silicon rubber(or epoxy resin) to make the exposure area to be 1cm2.
2.3 Solution
Add 4.5g pure NaCl into the 4 neck cell containing 500mL instilled water to make the 9g/L NaCl solution. Put the cell into thermostat water bath to keep temperature 37±1℃.
3. Experiment Steps
Put the sample, salt bridge and Platinum plate electrode into the thermostat 4-neck cell. The distance between the tip of the salt bridge and the sample’s center should be 1~2mm. The green clamp(WE) connects to the sample, the yellow clamp(RE) connects to SCE, and the red clamp(CE) connects to the platinum plate electrode.
Pic 1. Experiment setup
Pic 2. Three-electrode system
Switch on the instrument and open the software. Choose Experiment→ Stable polarization→ potentiodynamic. Parameters setting is shown in Pic. 3. You should build a new file name before measuring. Pic 3. Parameters setting dialog box for pitting potential measurement
Before measurement, you should set the measuring area of the sample and the RE type. You can click Cell . You should wait a while till the system is stable.
Pic 4. Sample area and RE setting
Pic 5. OCP Check
Check “Use” in “OCP Check”, then start the testing. When the system is stable, the software will automatically do the potentiodynamic scan. When the process is finished, measurement will be stopped automatically. For every batch of product, you should choose three parallel samples.
4. Results
In the main menu, please click Tools for data analysis. Click following icon to import the data file for analyzing.
Pic 6. Open the data file
Set the coordinate as E vs. LogI, move the slider to choose the point where the current increases most dramatically. The corresponding potential of this data point is pitting potential, see the pic 7.
Pic 7. pitting potential analysis
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