Surface evolution analysis of CrxWyNz coatings on WC mold in glass molding process

Abstract

The CrxWyNz coatings were synthesized on the cemented carbide (WC-8Co) by plasma-enhanced magnetron sputtering (PEMS). The detailed glass cylinder compression was tested for the molding performance of the coated molds in the precision glass molding machine (PGMM). This work examined the surface morphology evolution, elemental compositions and mechanical properties of the CrxWyNz coatings by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS), nano-indentation tester and atomic force microscope (AFM). The results showed that with the increased W content in the CrxWyNz coatings, the nano-hardness and Young's modulus of the coatings increased, and the surface roughness of the coatings reduced. The contact zone had lower surface roughness than the non-contact zone because of inhibiting the oxidation reaction. The molded glass pressing on the surfaces of Cr27W24N49 and Cr18W28N54 coatings had relatively better light transmittance. Besides, the CrxWyNz coatings (18 ≤ x ≤ 27, and 24 ≤ y ≤ 28) exhibited better oxidation resistance, chemical inertness, and surface quality during thermal-mechanical cycles, more suitable for glass molding protective coatings. The work sheds light on the preparation and application of glass molding protective coatings.