Deposition of thick nitrides and carbonitrides for sand erosion protection

Thick nitrides (ZrN, CrN and TiN) and carbonitrides (ZrSiCN and TiSiCN) have been deposited using a Plasma Enhanced Magnetron Sputtering (PEMS) technique. The technique combines a conventional magnetron sputtering and an independently generated plasma from which high current density can be obtained. By using heavy ion bombardment prior to and during deposition to increase the coating adhesion and limit columnar growth, single-layered thick nitrides of ZrN, CrN, and TiN coatings up to about 80 μm and thick carbonitride coatings of ZrSiCN and TiSiCN about 30 μm have been obtained. In this paper, we will discuss the deposition technology and the properties of the thick coatings. Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS), and X-Ray Diffractometry (XRD) were used to study the microstructure and morphology of these coatings. Nanoindentation was conducted to determine the hardness and Young's modulus, while sand erosion tests were conducted to rank the erosion resistance of the coatings. It was observed that TiSiCN rendered the best erosion resistance — nearly 25 times higher than the uncoated stainless steel or Ti–6Al–4V and about 5–10 times higher than all other nitrides. The technology may be applied to protect turbine engine compressor blades, vanes and rotor blades in advanced aircraft and fluid pump impellers as well as piston rings for heavy-duty diesel engines.