Comparative Study of Multilayer Hard Coatings Deposited on WC-Co Hardmetals

Abstract

This paper examines the impact of a multilayered gradient coating, applied via plasma-activated chemical vapor deposition (PACVD), on the structural and mechanical attributes of nanostructured WC-Co cemented carbides. WC-Co samples containing 5 and 15 wt.% Co were synthesized through a hot isostatic pressing (HIP) process using nanoparticle powders and coated with two distinct multilayer coatings: titanium nitride (TiN) and titanium carbonitride (TiCN). Nanosized grain formation without microstructural defects of the substrates, prior to coating, was confirmed by magnetic saturation and coercivity testing, microstructural analysis, and field emission scanning electron microscope (FESEM). Nanoindentation, fracture toughness and hardness testing were conducted for uncoated samples. After coatings deposition, characterizations including microscopy, surface roughness determination, adhesion testing, coating thickness measurement, and microhardness examination were conducted. The impact of deposited coatings on wear resistance of produced hardmetals was analyzed via scratch test and dry sliding wear test. Samples with higher Co content exhibited improved adhesion, facilitating surface cleaning and activation before coating. TiN and TiCN coatings demonstrated similar roughness on substrates of identical composition, suggesting Co content’s minimal influence on layer growth. Results of the mechanical tests showed higher microhardness, higher elastic modulus, better adhesion, and overall superior tribological properties of the TiCN coating.

Preparation and Performance of a Cr/CrN/TiAlCN Composite Coating on a GCr15 Bearing Steel Surface

“…Compared with other methods, magnetron sputtering technology has the advantages of high speed, low temperature, low damage, and uniform coating; thus, it can effectively solve these defect problems. Coating surface treatment technology can significantly improve the performance of materials, and the reasonable design of multi-layer composite coatings in coating surface treatments is expected to provide further modifications [13][14][15][16]. The matrix material used in this study was GCr15 bearing steel, which is the most commonly used in engineering practice.…”