Growth and characterization of multilayer hot-filament chemical vapor deposition diamond coatings on WC–Co substrates

Abstract

The diamond coating of tungsten carbide (WC)–cobalt (Co) hard metals has been the focus of various research activities mainly due to growing interest in diamond-coated tools for industrial machining of different materials. In this work, multilayered diamond coatings have been grown on pretreated tungsten carbide–cobalt substrates by hot-filament chemical vapor deposition. Two types of multilayer coatings have been prepared: (a) three-layer (alternating nanocrystalline diamond and microcrystalline diamond films) and (b) five-layer (alternating ultrananocrystalline and microcrystalline diamond films). The morphology, roughness, structure, thickness, adhesion of these coatings have been investigated using atomic force microscopy, field emission gun scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy, nanoindentantion and Rockwell C indentation tests at 600 N load. Raman spectra of the two types of samples exhibited sharp characteristic bands of nanocrystalline diamond and a centered peak at 1340 cm−1. The displacement of this peak in relation to the natural diamond peak (1332 cm−1) can be attributed to graphitic inclusions in diamond grain boundaries and the thermal coefficient mismatch of the multilayer coating–substrate system. Roughness surface measurements showed very smooth surfaces for both samples. Although the substrate has a high binder content, the results show that well-adhered chemical vapor deposition diamond multilayer coatings were produced.

Cutting Performance and Wear Mechanism of Multilayer Diamond‐Coated Tools

“…The growth rate of diamond films generally varies depending on several factors, such as the concentration of CH 4 , the diameter of the filament, the size of the reactor chamber, level of seeding, initial surface roughness, among others. [ 21 ] The parameters were chosen in such a manner that the thickness of the coatings had as close as possible similar final values. Multilayer diamond films with MCD/NCD alternate structure and MCD/SMCD/NCD gradient structure were prepared by adjusting the CH 4 concentration at 1%/5% (1% for MCD/5% for NCD) and 1%/3%/5% (1% for MCD/3% for SMCD/5% for NCD), respectively.…”

Growth and Characterization of Polycrystalline CVD Diamond Films Obtained by MWPACVD at High Power 2,45GHz Microwave Discharge

“…It is also noteworthy that all the samples presented a sharp diamond peak with similar FWHM values, what indicates that the diamond material deposited presents good quality in all samples, however what makes the film a better or worse material is the amount of non-diamond phases incorporated in the coating. The increase of pressure or reduction of temperature is a widely used procedure for controlling grain size of diamond crystals produced by CVD, reported in some of our previous works [51][52][53] and from others [54][55][56] .…”