铬薄膜的热氧化：初始金属结构的作用

Chromium films are widely investigated as protective coatings for applications requiring high oxidation resistance, long-term performance being obtained by the formation of a stable Cr 2 O 3 layer. Although chromium oxidation has been extensively studied, the influence of the initial characteristics of Cr coatings on their morphological, microstructural and mechanical evolution during thermal oxidation remains poorly understood. In this work, Cr thin films deposited by Direct Current Magnetron Sputtering (DCMS), High-Power Impulse Magnetron Sputtering (HiPIMS) and bipolar HiPIMS were oxidized in air between 400 and 800 °C. Different deposition routes produced samples with distinct densities, morphologies and microstructures, enabling systematic investigation of the role of the initial metallic architecture in oxidation behavior. SEM, GIXRD, Raman spectroscopy and Surface Brillouin Spectroscopy were combined to follow the evolution of the chromia layer and the underlying metallic Cr film. The results show that the initial characteristics of the metallic precursor influence oxygen transport, chromia development and oxide structural evolution. Open columnar films exhibit earlier evidence of oxidation and develop thicker, less ordered chromia, whereas denser, more compact architectures show delayed evidence of oxidation and produce thinner, more homogeneous and structurally ordered Cr 2 O 3 layers. Mechanical characterization further reveals elastic stiffening associated with oxide growth and thermally activated structural rearrangement of the metallic film. These findings demonstrate that tailoring the initial architecture of sputtered Cr thin films provides an effective route to control the development and quality of protective chromia layers.