me corrosion project 9/19/2017 1:10:52 am · 1 . me corrosion project 9/19/2017 1:10:52 am. point...

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ME Corrosion Project 9/19/2017 1:10:52 AM

Point of interest is located inside the coating (the bright white portion) to determine the most common elements inside the Maxon CRS. C, O, Na, Al, P, S, Cl, K, Ca, and Ba are possibly from Maxon CRS. Fe and Si are likely only present because of the proximity to the metal. Image Magnification: 60X Spot Size: 4.0 Accelerating Voltage: 20.0 keV (These remain constant for the entirety of this report)

Spectrum processing : No peaks omitted Processing option : All elements analyzed (Normalised) Number of iterations = 5 Standard : C CaCO3 1-Jun-1999 12:00 AM O SiO2 1-Jun-1999 12:00 AM Na Albite 1-Jun-1999 12:00 AM Al Al2O3 1-Jun-1999 12:00 AM Si SiO2 1-Jun-1999 12:00 AM P GaP 1-Jun-1999 12:00 AM S FeS2 1-Jun-1999 12:00 AM Cl KCl 1-Jun-1999 12:00 AM K MAD-10 Feldspar 1-Jun-1999 12:00 AM Ca Wollastonite 1-Jun-1999 12:00 AM Fe Fe 1-Jun-1999 12:00 AM Ba BaF2 1-Jun-1999 12:00 AM

Element Weight% Atomic% C K 62.05 72.77 O K 26.68 23.49 Na K 0.53 0.32 Al K 3.44 1.79 Si K 0.16 0.08 P K 0.08 0.04 S K 1.08 0.47 Cl K 0.36 0.14 K K 0.24 0.09 Ca K 0.20 0.07 Fe K 1.33 0.34 Ba L 3.84 0.39 Totals 100.00

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Depth: ~155 μm Maxon CRS elements present? Yes: Phosphorus Metal sample is steel with Mn and Si alloying elements. Carbon is omitted from some of the sample measurements (including this one) in this report to show how it affects the quantification measurements. The Kα energy level of carbon is within the range of background radiation. Without large quantities of carbon present the detector can give inaccurate estimates. Better measurements can be taken of carbon if the accelerating voltage is reduced. Accelerating voltages should be around 15-20 keV for exploratory analysis, but an acceleration voltage of 5-10 keV can improve accuracy of elements at low quantities. (http://www.charfac.umn.edu/instruments/eds_on_sem_primer.pdf) In future analysis the accelerating voltage will be changed to 5 so that accurate readings of the following elements can be obtained: C, O, P. Additional measurements were not taken after this test because the EDS detector stopped working properly and is currently awaiting service.

Spectrum processing : No peaks omitted Processing option : All elements analyzed (Normalised) Number of iterations = 2 Standard : Si SiO2 1-Jun-1999 12:00 AM P GaP 1-Jun-1999 12:00 AM Mn Mn 1-Jun-1999 12:00 AM Fe Fe 1-Jun-1999 12:00 AM

Element Weight% Atomic% Si K 0.28 0.56 P K 0.44 0.79 Mn K 1.24 1.25 Fe K 98.04 97.40 Totals 100.00

http://www.charfac.umn.edu/instruments/eds_on_sem_primer.pdf

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Depth: ~325 μm Maxon CRS elements present? No In this location of interest, the quantity of carbon is unrealistically high for a sample of steel. If this were to be taken as a sign of the presence of Maxon CRS we would expect to see similar levels of carbon measured depths equal to or less than this. This is not the case (see Line Spectrum 2(3) and Line Spectrum 2(4)).

Spectrum processing : No peaks omitted Processing option : All elements analyzed (Normalised) Number of iterations = 3 Standard : C CaCO3 1-Jun-1999 12:00 AM Si SiO2 1-Jun-1999 12:00 AM Mn Mn 1-Jun-1999 12:00 AM Fe Fe 1-Jun-1999 12:00 AM

Element Weight% Atomic% C K 10.29 34.71 Si K 0.25 0.36 Mn K 1.02 0.75 Fe K 88.44 64.18 Totals 100.00

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Depth: ~500 μm Maxon CRS elements present? No In this location of interest, the quantity of carbon is negative. This is because the background radiation levels happened to be lower than the detector expected at this energy level.


Element Weight% Atomic% C K -1.46 -7.15 Si K 0.39 0.82 Mn K 1.19 1.27 Fe K 99.88 105.06 Totals 100.00

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Depth: ~570 μm Maxon CRS elements present? No



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Depth: ~60 μm Maxon CRS elements present? No This could be a result of spectral interference that will be taken care of by reducing the accelerating voltage to 5 keV. Accuracy of energy levels < 3keV suffer at accelerating voltages of 20 keV due to frequent spectral interference (http://cfamm.ucr.edu/documents/eds-intro.pdf).



http://cfamm.ucr.edu/documents/eds-intro.pdf

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Depth: ~100 μm Maxon CRS elements present? Yes: Phosphorous

Spectrum processing : No peaks omitted Processing option : All elements analyzed (Normalised) Number of iterations = 2 Standard : C CaCO3 1-Jun-1999 12:00 AM Si SiO2 1-Jun-1999 12:00 AM P GaP 1-Jun-1999 12:00 AM Mn Mn 1-Jun-1999 12:00 AM Fe Fe 1-Jun-1999 12:00 AM

Element Weight% Atomic% C K -12.99 -113.80 Si K 0.30 1.12 P K 0.24 0.81 Mn K 1.16 2.23 Fe K 111.29 209.64 Totals 100.00

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Spectrum processing : Peak possibly omitted : 8.360 keV Processing option : All elements analyzed (Normalised) Number of iterations = 2 Standard : Si SiO2 1-Jun-1999 12:00 AM P GaP 1-Jun-1999 12:00 AM Mn Mn 1-Jun-1999 12:00 AM Fe Fe 1-Jun-1999 12:00 AM


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Spectrum processing : No peaks omitted Processing option : All elements analyzed (Normalised) Number of iterations = 2 Standard : Si SiO2 1-Jun-1999 12:00 AM P GaP 1-Jun-1999 12:00 AM Mn Mn 1-Jun-1999 12:00 AM Fe Fe 1-Jun-1999 12:00 AM


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Spectrum processing : No peaks omitted Processing option : All elements analyzed (Normalised) Number of iterations = 2 Standard : C CaCO3 1-Jun-1999 12:00 AM Si SiO2 1-Jun-1999 12:00 AM P GaP 1-Jun-1999 12:00 AM Mn Mn 1-Jun-1999 12:00 AM Fe Fe 1-Jun-1999 12:00 AM

Element Weight% Atomic% C K -6.19 -36.89 Si K 0.30 0.76 P K 0.39 0.89 Mn K 0.93 1.21 Fe K 104.58 134.03 Totals 100.00

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Depth: ~315 μm Maxon CRS elements present? Yes: Phosphorous Carbon

Oxygen Aluminum

Spectrum processing : No peaks omitted Processing option : All elements analyzed (Normalised) Number of iterations = 4 Standard : C CaCO3 1-Jun-1999 12:00 AM O SiO2 1-Jun-1999 12:00 AM Al Al2O3 1-Jun-1999 12:00 AM Si SiO2 1-Jun-1999 12:00 AM P GaP 1-Jun-1999 12:00 AM Mn Mn 1-Jun-1999 12:00 AM Fe Fe 1-Jun-1999 12:00 AM

Element Weight% Atomic% C K 12.87 34.32 O K 10.39 20.80 Al K 0.35 0.42 Si K 0.55 0.62 P K 0.73 0.76 Mn K 0.72 0.42 Fe K 74.39 42.66 Totals 100.00

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Summary Report Procedure: A steel sample with Mn and Si alloying elements was coated in Maxon CRS and allowed to sit in an open environment at room temperature for five days. Then the sample was prepared for SEM metallography according to ASTM E3-11 without a mount. An SEM image was produced at 60X magnification in a vacuum chamber with an accelerating voltage of 20.0 keV and spot size of 4.0. This accelerating voltage was chosen because it is the typical accelerating voltage used for taking images of metal samples and is appropriate for exploratory analysis (http://www.charfac.umn.edu/instruments/eds_on_sem_primer.pdf). There were plans for follow up analysis with lower accelerating voltages and samples cured at 2 and 7 days, but was postponed because of issues with the EDS detector. Data: Measurements were taken along even increments in two straight lines normal to the surface of the sample and starting at the Maxon CRS coating. The first line consists of points of interest labeled “Line Spectrum(1-5)”. The second line consists of points of interest labeled “Line Spectrum(1-10)”. Table I orders the results by the depth of point of interest from the surface of the sample.

Table I. Summary Table of Results Depth (μm) Maxon CRS

elements present? Specific Maxon CRS elements present

Point of interest label

60 No Line Spectrum 2(8) 100 Yes P Line Spectrum 2(4) 145 Yes P Line Spectrum 2(5) 155 Yes P Line Spectrum(2) 185 Yes P Line Spectrum 2(6) 230 Yes P Line Spectrum 2(7) 270 No Line Spectrum 2(8) 315 Yes P, C, O, Al Line Spectrum 2(9) 325 No Line Spectrum(3) 355 No Line Spectrum 2(10) 500 No Line Spectrum(4) 570 No Line Spectrum(5)

http://www.charfac.umn.edu/instruments/eds_on_sem_primer.pdf

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Analysis: The results from this preliminary study show that phosphorus was detected at depths about 315 μm after five days. Phosphorus appears to be an element present in Maxon CRS (as evidenced by the presence of phosphorus in the spectrum of point of interest “Line Spectrum(1)”). This suggests that Maxon CRS penetrated the steel sample by at least 300 μm in five days. This should be confirmed by performing a test at a lower accelerating voltage (5 keV) to provide more accurate readings for elements with lower energy levels (such as carbon, oxygen, and phosphorus). This will enable quantitative analysis showing accurate amounts of these elements at locations where the Maxon CRS has and has not penetrated. A significant difference in relative amounts of these elements will be interpreted as the presence of Maxon CRS coating. Difficulties/Solutions: The equipment being used is relatively old. It still provides accurate results, but can be considerably unreliable. It is common that SEM filaments are blown and need to be replaced or other technical issues cause the EDS detector to stop working. When this happens, work must stop and wait for service from the lab technician. Maintenance is rarely completed in the same day. Due to the nature of this study this could mean that samples that are meant to be measured a specific number of days after they were coated can fail to be measured on-time. This means that the team needs to wait another week for more samples to be prepared. This is the reason the preliminary study was not fully completed this summer. This issue can be addressed by preparing samples every day of the week until all the measurements have been taken. Samples will be measured at the first available opportunity that the SEM is available, working, and the samples have been allowed to cure for the appropriate number of days. This will require the project to purchase larger amount of materials and Maxon CRS for the penetration tests in preparation for wasting some number of prepared samples. It is also important to acknowledge that the team may spend time preparing samples according to ASTM standard E3-11 and then have the SEM break during the tests (like it did during the tests for the 2 and 7 day samples for this preliminary test). Report Written By: Wesley Powell (MS Industrial Engineering, BS Materials Engineering) SEM/EDS Operator: Wesley Powell

me corrosion project 9/19/2017 1:10:52 am · 1 . me corrosion project 9/19/2017 1:10:52 am. point...

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