Analysis of Different Complex Multilayer PACVD Coatings on Nanostructured WC-Co Cemented Carbide

Abstract

The development of cemented carbides nowadays is aimed at the application and sintering of ultrafine and nano-sized powders for the production of a variety of components where excellent mechanical properties and high wear resistance are required for use in high temperature and corrosive environment conditions. The most efficient way of increasing the tribological properties along with achieving high corrosion resistance is coating. Using surface processes (modification and/or coating), it is possible to form a surface layer/base material system with properties that can meet modern expectations with acceptable production costs. Three coating systems were developed on WC cemented carbides substrate with the addition of 10 wt.% Co using the plasma-assisted chemical vapor deposition (PACVD) method: single-layer TiN coating, harder multilayer gradient TiCN coating composed of TiN and TiCN layers, and the hardest multilayer TiBN coating composed of TiN and TiB2. Physical and mechanical properties of coated and uncoated samples were investigated by means of quantitative depth profile (QDP) analysis, nanoindentation, surface layer characterization (XRD analysis), and coating adhesion evaluation using the scratch test. The results confirm the possibility of obtaining nanostructured cemented carbides of homogeneous structure without structural defects such as eta phase or unbound carbon providing increase in hardness and fracture toughness. The lowest adhesion was detected for the single-layer TiN coating, while coatings with a complex architecture (TiCN, TiBN) showed improved adhesion.

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

“…Examination of magnetic characteristics showed saturation magnetization, registering 7.97 µTm 3 /kg for WC-5Co samples and 22.10 µTm 3 /kg for WC-15Co samples. These observations indicate a favorable sintering environment, which helps prevent the occurrence of microstructural abnormalities, such as the presence of η-phase or unbounded carbon [28].…”

“…High-quality pure gases (H 2 , Ar, N 2 ) and the precursor TiCl 4 were utilized in the coating procedure. The TiN coating was applied for a duration of 6 h at 530 • C. Following the coating process, the samples were gradually cooled to room temperature using a hydrogen flow rate of 100 L/h for 1.5 h [28].…”

“…The deposition temperature throughout the coating process was maintained at 530 • C. The transition from the TiN to TiCN layer was achieved through modulation of N 2 content and the introduction of CH 4 [28].…”

“…Comprehensive details regarding all listed testing procedures performed on the samples of WC-5Co and WC-15Co are extensively documented in the literature [13,27,28].…”

Improvement of the Tribocorrosion Properties of Cemented Carbide (WC-Tic-Co) Samples with PVD Coating

“…[43]. Lower values of both Lc2 and Lc3 were reported for multilayer PACVD coatings deposited on nanostructured WC-Co cemented carbides [44]. Sezer çam et al, instead, presented values of critical loads of approximately 90-100 N for CrAlSiN and TiAlN/TiSiN coatings deposited on tungsten carbide (WC-12Co) by cathodic arc physical vapor deposition [39].…”