I've made a coating for anticorrosion study. Now, since I used Zn0 as one of the component, the color of the coating is white.
As far as I can see in this situation, If I proceed to the Scanning Electron Microscope (SEM) with the coating still attach onto the metal coupon. Wouldn't it means that, Im going to get the SEM picture of only the top surface of the coating and not the surface of the metal? Since the color of coating is white and not transparent.
So, should I removed the coating first then proceeds to SEM so that I can see clearly what happen on the surface of the metal coupon?
Thank you for answering :)
For analyzes of coatings (optical microscopy, SEM, EDS and others) cross sections of the coated piece are used. Only with a cross section you can see everything in one picture: interface with the substrate, internal coating structure and the extenal coating layers.
For analyzes of coatings (optical microscopy, SEM, EDS and others) cross sections of the coated piece are used. Only with a cross section you can see everything in one picture: interface with the substrate, internal coating structure and the extenal coating layers.
Hello Ikhmal,
As per your question, I infer that your intent is to study the coating and how it has affected the substrate (metal coupon). I agree with Prof. Vadim Verlotski. If you are studying how the coating is impacting the substrate, then it would be ideal to study the cross section of the sample.
In addition to that, the most ideal method to examine the top surface of coating would be to put a masking tape on the substrate prior to depositing the coating. Remove the masking tape just before SEM examination to reveal a region with bare substrate and coated substrate. This would make a clear comparison in terms of microstructure.
If you have already coated the substrate, then the only way to study is to partly scratch the coating to reveal the substrate. This would risk damaging the coating, substrate and the entire sample. I would not recommend this.
Thanks.
Depends on what you want to see. If it is a surface of metal, then sure, you have to remove coating very thoroughly (and do not damage surface in a process). Not a problem if your coating is soluble, otherwise near impossible. If you are interested in inner structure of a metal specimen, you may want to make a cross section (by cutting and polishing, or fracture it).
All recommendations given above are perfect. Obey them. To be more scientific, think of what SEM shows you. It shows the morphology of whatever you're examining by using electron scattering from the surface. Therefore the surface color or transparency have nothing to do with SEM. It employs electrons not optical light.
If you're examining the surface of coating use it as it is. If you are examining the metal-coating interface examine the cross section. Removing the coating may help but it may also yield you a false surface depending on how successfully you can make it.
Sir, in this condition we usually cut the sample into its cross-section and then do the sem from that side to clearly observe the coating depth and its impact on the surface of the substrate.
Thank you very very much for all the answers. I really appreciate all of them a lot! It give me quite good a idea on how do I need to proceed. Thank you again!!
Dear Lkhmal,
SEM will provide you the image of the metal surface. Surface morphology can be study using SEM analysis. You should not remove the protective film. As you are studying adsorption of inhibitor on the metal surface, you should go for AFM, SEM/EDS, XPS etc. analysis. Hope this will help you.
I applied the paint film on a clean flat glass substrate (amorphous). After drying, A plier was used to broke the flat glass into small pieces that I put on the stand and then investigated using EDS. This may be used to observe both paint film surface and section. In section, I investigated mean paint thickness, arrangement of pigment and filler, distribution of blender, to check if any vertical stratification exists, etc. Results were very good. I can send you the SEM if you need it.
Dear Aloui Tahar,
That would be very nice Sir. Thank you very much.
Please find here a paper which deals with this topic.
Article Ground calcium carbonate (GCC) from the Barre de Ghomrassene...
Any suggestions for charging effect effect that troubles SEM imaging ?
Hi,
Charging is primarily caused by accumulation of electrons on the sample. To dissipate these electrons, the sample need to be grounded well. However, this may be a challenge, particularly when the sample is non conductive. The conventional practice is to attach carbon or copper tapes to ground the sample to the sample holder and ensure a conductive path. Or, you may use gold sputtering. However, be mindful that excessive gold sputtering could potentially mask minuscule features on the sample that you might want to see, in case features are in sub micron scales.
For instance, sputter coat the sample gradually (say 5, 10 sec and high) and then check the occurrence of charging.
Additionally, you may even try using a low vacuum atmosphere, a low beam voltage or low scanning rate without compromising much on the image resolution and quality. Hope this helps.
its depends on the thickness and type of coating, generally single layer coating have very less effect on substrate, if it is conductive. so go through the details and coating.
- Badges
- Science topic