Case Study Characterization of CrC Coating:
Material:
- Low carbon steel
Samples:
- Steel strip (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 7-8 µm in diameter
- The microstructure in the cross-section of sample 1 in Figure 2 reveals a uniform coating thickness of 12 µm from both sides
- No defects, such as porosity or contamination, are revealed within the coating or at the interface
- The base material has a ferrite microstructure
- Higher magnification photos of the microstructure appear in Figures 3 and 4
- The micro-hardness indentations are seen in Figure 3. The micro-hardness level was found to be 3000-3500HV within the coating
- 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
Other Characteristics:
- Phase content of the coating: Cr7C3 + Cr23C6
- Micro-hardness of the layer: 2,000 – 2,200 HV
- Micro-hardness of the base metal: 700 – 800 HV
- Layer thickness: 0.0004” – 0.0006”
- Very low coefficient of friction
- No coarsening of the base metal
