Charactarization of CRC Coating
June 12, 2003
Material: low carbon steel, a 0.8mm thick strip with coating.
Samples: Plate (1”x1”x0.03”)
The characterization included the following methods:
- SEM analysis of surface morphology
- Metallographic examination
- Microhardness testing.
- X-ray diffraction
- High resolution SEM
Results
The surface morphology of sample #1 is shown in Figure 1 and is characterized by spherical particles pattern, 7-8 µm diameter.
The microstructure in the cross-section of sample #1 reveals uniform coating thickness of 12 µm from both sides- Fig 2. No defects, like porosity or contamination were revealed within the coating or at the interface. The base material has ferrite microstructure. At higher magnifications the microstructure appear in Figures 3 and 4.
The micro hardness indentations are seen in Figure 3. The microhardness level was found 3000-3500HV within the coating (190 HV in base metal).
High Resolution HR SEM was applied to examine the grain structure of the coating from the surface. Figures 5 and 6 confirm the nanostructure of the coating to be 20-30nm.
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| Fig 1: The surface morphology of sample #1 | Fig 2: Sample #1. The coating thickness is uniform- 12µm |
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| Fig 3: The microhardness indentations | Fig 4: SEM No defects within the coating or at the interface |
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| Fig 5: High resolution SEM of the surface, x100.000 | Fig 6: HR- nano crystals-on surface look |