Al₂O₃ coatings were fabricated on CLAM steel substrates at 300 °C by RF magnetron sputtering, and Si_xC_1 − x coatings with different Si concentrations were then fabricated on the Al₂O₃ coatings by pulse magnetron sputtering. The coating composition, topography, structure and mechanical properties were investigated by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), X-ray diffractometry (XRD), Raman spectroscopy, nano-indentation techniques and scratch tests. The results show that Si_xC_1 − x coatings had Si contents in the range 39–62 at.%. Al₂O₃ coatings exhibited an island growth mode, while Si_xC_1 − x coatings showed a step flow growth mode. Compact and crack-free Si_xC_1 − x/Al₂O₃ Coatings were prepared. α-Al₂O₃, α-Cr₂O₃ and spinel Fe₂CrO₄ were all detected in the Al₂O₃ coating by Raman spectroscopy. The hardness and elastic modulus of the Al₂O₃ coating were 15.5 ± 1.0 and 194.8 ± 7.2 Gpa, respectively. The hardness and elastic modulus of Si_xC_1 − x layer were 28.6 ± 0.8 Gpa and 219.2 ± 2.6 Gpa, respectively, for Si content of ≈ 49 at.%. The adhesion of C-rich and stoichiometric Si_xC_1 − x/Al₂O₃ coatings were superior to those of Si-rich coatings.