Imaging Processing with Pax-it Software (Analyzing the Percentage of Carbon Content)

Transcription

1 Imaging Processing with Pax-it Software (Analyzing the Percentage of Carbon Content) 1. Setting Up a. Log on to the computer with your NSID and password. b. Place your sample in the sample holder in the Optical microscope and rotate to the lowest magnification lens. First of all, view the sample image using the Optical microscope eyepiece. 2. Capturing Images a. Launch the PAX-it software by double clicking the icon on the desktop, and wait for the software to load as shown in Fig. 1. Figure 1. Image of PAX-it software background b. To acquire images, after launching the PAX-it software, click on the PAXcam icon as shown in Fig. 2.

2 Figure 2. Image of the PAXcam icon. c. A new window showing a typical image of the sample will appear as shown in Fig. 3. Once you are okay with the image, click the capture icon as shown in Fig. 3. Figure 3. Image showing the capture button. d. After capturing the image, all necessary information used in taking the image must be entered accordingly. The Title, Camera name, and Magnification all must be entered.

3 Figure 4. Image showing the location of the parameters to be entered in naming the image captured. e. The scale bar for the captured image must be entered in relation to the magnification used in acquiring the image as seen in Table 1. Click on the scale bar icon as shown in Fig. 5. Table 1. Values of magnification with respect to scale bar. Magnification Scale bar 1000x 10um 500x 20um 100x 100um 50x 200um Figure 5. Image showing the scale bar icon.

4 f. A new window appears as seen in Fig. 6 that allows you to enter the scale bar value with respect to the magnification used in acquiring the image. After entering the scale bar value, you can also select the colour, and click okay. It is advisable that the scale bar icon on the image is moved to the bottom right-hand corner as seen in Fig. 7. Figure 6. Image showing the scale bar properties. Figure 7. Image showing position of the scale bar.

5 g. It is important that after putting the scale bar on the image, a picture showing both the image and scale bar is to be copied and saved. NOTE: Any image taken without a scale bar is useless. 3. Analyzing the % Carbon Content As observed from the image, there are two different regions or areas. To analyze one of the areas the following steps are followed. a. Click on the detect areas icon as shown in Fig. 8 and a new window comes up as shown in Fig. 9. Figure 8. Image showing the detect areas button. Figure 9. Image showing the analysis window.

6 b. Select New Analysis, and click the Next button twice. A new window appears as seen in Fig. 10. Ensure Detect Areas only button is selected. Click on the Add button to add an area of interest to be analyzed. Then select the Next button. Figure 10. Image showing the detect areas button. c. The total area covered by the image is given in the new window as shown in Fig 11. This area is expected to be written down somewhere. It will be used later in the analysis. Figure 11. Image showing the total area covered by the image.

7 d. After taking note of the total area covered, click the Next button. A new window comes up as shown in Fig. 12. Two buttons are of interest in this window, the colour slider and the invert threshold buttons. Figure 12. Image showing both the colour slider and invert threshold button. e. Since there are two areas or region (the dark and the light areas), one of the areas of interest is shaded by moving the colour slider upwards and downwards slowly. The aim here is to ensure one of the areas, is completely shaded without shading the other area. f. To change the area to be shaded, click on the Invert threshold button. Once the area of interest has been fully shaded, click the Next button. A new window comes up as seen in Fig. 13. To know the percent region of interest (ROI) that was shaded, click on the Measurement Total. Then click the Finish button.

8 Figure 13. Image showing the measurement total button. Both the values of the area that was shaded and percent ROI are displayed in the report as seen in Fig. 14. Figure 14. Image showing the experimental value of the percent ROI of the shaded area.

9 The percent ROI of the other area, is calculated by subtracting the percent ROI of the shaded area from 100%. The percent ROI was calculated by the software using equation 1. A p. ρ p Mass Fraction of Pearlite (W p ) = (A p. ρ p ) + (A α. ρ α ) 100% where A p, A α, ρ p, ρ α are the area fractions of pearlite, area fractions of ferrite, density of pearlite (7.84 g/cm 3 ) and density of ferrite (7.87 g/cm 3 ) respectively. The density of cementite is 7.64 g/cm 3. The area fraction of pearlite is calculated by dividing the shaded pearlite area by the total area.