Preliminary study of α-Ta multilayer alternating coating: Through bias control

To achieve high properties of α-Ta alternating multilayer coatings, arc-enhanced glow discharge (AEGD) and high-power impulse magnetron sputtering (HiPIMS) techniques were used in this work. By integrating direct-current magnetron sputtering (DCMS) with HiPIMS, single-layer and multilayer coatings were successfully produced at a deposition rate exceeding 6 μm/h. The microstructure, mechanical properties, electrochemical behavior, and thermal shock resistance of the coatings were investigated in this work. When the difference in alternating bias exceeds 150 V, the dislocation distribution and grain morphology both exhibit a distinct layered distribution. The adjustment of bias voltage did not affect the crystal structure, fracture toughness, and adhesion strength of the multilayer alternating coatings. Simultaneously, specific properties could be modulated within a defined range, including hardness (600–775 HV0.05), electrical resistivity (15–25 μΩ·cm), and self-corrosion current density (1.40 × 10⁻⁸-9.00 × 10⁻⁹ A·cm⁻²). Notably, coatings fabricated under optimized alternating bias exhibited exceptional stability, covering all substrate surfaces even after exposure to 50 thermal shock cycles from 700 to 25 °C.