Problem:
Under mechanical stress, the cable insulation breaks and peels off the copper wire.
Investigation strategy:
For damage analysis, an electron microscopic fracture and defect analysis with material characterization was carried out.
Results:
- SEM-EDX analysis of the fracture site:
- The insulation material is a fluorinated plastic.
- Damage pattern shows a violent break.
- Material identification using FTIR:
- Plastic was identified as PTFE.
- No foreign substances or contaminants detected.
- Determination of the degree of sintering using DSC:
- Crystallinity of PTFE after melting is significantly higher than in the initial state.
Conclusion:
The fracture was caused by insufficient cohesion or cross-linking. Analysis revealed that the PTFE was not sufficiently sintered during manufacturing.
Recommended follow-up examination:
Optimization of the temperature program for post-sintering in the installed state using DSC.
