Synthesis and exploration of heat transfer properties in diamond-like carbon copper composite films deposited on stainless steel substrates

This research article investigates the enhancement of heat transfer in stainless steel plates by augmenting the surface area and enhancing the thermal conductivity of the surface through the application of a-DLC:H in combination with copper layers. The increase in the surface area of the plate is achieved via surface mechanical attrition treatment (SMAT), while the a-DLC:H and copper coatings are applied using PECVD and PVD techniques, respectively. The application of SMAT on the surface before the deposition of the DLC/Cu composite film resulted in a substantial increase in surface area, reaching approximately 80 %, while also improving adhesion and thermal contact efficiency. A comprehensive examination of the growth morphologies demonstrated the development of ultra-fine nano-crystalline diamond (UNCD). The Raman spectra displayed a prominent peak at 1160 cm-1, corresponding to sp3-bonded carbon representing D peak of nano-crystalline diamond. Additionally, a distinct Cu-O peak at 450 cm- 1 was observed, indicating atmospheric oxidation of copper on the surface. Surface profiling using a 3D profilometer and Raman mapping demonstrated a uniform coating across the surface with a thickness of 240 nm. The integration of SMAT and coating treatment led to a significant enhancement in heat flux, reaching 450 W/m2. In contrast, uncoated surfaces exhibited a heat flux of 100 W/m2, while DLC/Cucoated surfaces without SMAT achieved a heat flux of 425 W/m2. Additionally, thermal conductivity improved from 509 W/(m center dot K) for DLC/Cu-coated steel to 565 W/(m center dot K) for SMAT-treated, DLC/Cu-coated steel, indicating superior thermal performance due to the synergistic effects of increased surface area and coating.