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Microstructure of base material plays an important role in adhesion strength and mechanical properties of Titanium Nitride (TiN) coating especially to increase the lifecycle of parts when in practical use. Present study covers the influence of grain size/microstructure of plain carbon steel (tailored via heat treatment) on TiN thin films deposited by physical vapor deposition (PVD) technique. Strong effect of grain size (microstructure) on adhesion strength of TiN thin films on annealed, normalized and quenched substrates have been observed. Mechanical characterization of TiN films e.g. Elastic modulus (E), Hardness (Hv), Stiffness (S) etc. have been studied via nano-indentation technique. TiN thin films failure investigation has been performed with Micro scratch testing under progressive load. Film exfoliation under critical loads has been corroborated via scanning electron microscopy (SEM). The results showed that TiN films deposited on fine microstructure substrate possess excellent mechanical properties and good adhesion strength as compared to coarser microstructure substrate. Insights of this study might be helpful in designing engineered thin films on optimized microstructures.

Failure of tubes is a very critical problem in boilers. The current study describes the detailed investigation for failure of boiler tubes in the power plants. Different characterization techniques like; metallography/microscopy, hardness, chemical analysis, SEM/EDS were utilized to find out the actual cause of failure. The tubes were failed within one year of its service. It was concluded that the brittle fracture (rupture) of tubes was occurred due to over-heating caused the formation of thermally insulating thick iron oxide scale on the inner surface of the boiler tube. Evidence of hydrogen embrittlement of the boiler tube in the rupture region was also found. Insights of this investigation might be helpful for the prevention of this type of failures in future.

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