Replacement of Hard Chromium Coating with thermally Sprayed HVOF Cr3C2-NiCr Coating to Improve Wear Resistance of Heavy Industrial Dies

Usual techniques such as PVD and CVD are not used for coating heavy industrial dies due to their size, and to increase their wear resistance and lifetime, conventional Hard chromium plating is used. The substitution of this technique with safer and more efficient ways has been recently studied and performed due to environmental pollution and restrictions for using Cr(VI) compounds, which are known to be carcinogenic. The aim of this research is to increase the life time of Dies by replacing Hard chromium with Thermal Spraying process. In order to this replacement, HVOF Thermal Spraying and 75Cr3C2-25NiCr cermet were selected as coating process and material respectively. Also, the Thermal Spray process was optimized by using The S/N ratio analysis approach and selecting four Kerosene Flow Rate (KFR), Feed Rate (FR), Spray Distance (SD) and Substrate Surface Roughness (SSR) parameters. Pin and Disc wear tester was used to compare wear rate of these coatings. The results showed significant decrease of wear rate on the thermally sprayed samples. The results Also showed a desirable improvement of wear rate by optimizing parameters. Eventually, it is expected that the life time of dies should increase a lot.