Four nitride coatings, TiN, TiAlN, AlTiN and CrAlN were deposited on YG6 (WC + 6 wt.% Co) cemented carbide by cathodic arc-evaporation technique. The friction and wear properties were investigated and compared using ball-on-disc method at high speed with SiC ball as a counter material. The tests were evaluated by scanning electron microscopy, X-ray diffractometer, energy dispersive X-ray, micro hardness tester and an optical profilometer. The results showed that TiN and TiAlN coatings presented lower friction coefficient and lower wear rate, and that high Al content AlTiN and CrAlN coatings didn't present better anti-wear properties in this test. Oxidation and abrasive wear were the main wear mechanism of TiN coating. In spite of the observation of micro-grooves and partial fractures, TiAlN possessed perfect tribological properties compared with the other coatings. High Al content increased the chemical reactivity and aroused severe adhesive wear of AlTiN coating. CrAlN coating presented better properties of anti-spalling and anti-adhesion, but abundant accumulated debris accelerated wear of the coating under this enclosed wear environment.

Friction and wear properties of TiN, TiAlN, AlTiN and CrAlN PVD nitride coatings

About 1.5-um-thick single-layer TiN, CrN, TiAlN coatings and nanolayered TiN/CrN, TiAlN/CrN multilayer coatings were deposited on silicon (111) substrates using a13; reactive direct current magnetron sputtering process. Structural characterization of the coatings was done using x-ray diffraction (XRD) and micro-Raman spectroscopy. All13; the coatings exhibited NaCl B1 structure in the XRD data. Raman spectroscopy data of as-deposited coatings exhibited two broad bands centered at 230x2013;250 and 540x2013;630 cmx2212;1.13; These bands have been assigned to acoustical and optical phonon modes, respectively. Thermal stability of the coatings was studied by heating the coatings in air in a13; resistive furnace for 30 min in the temperature range 400x2013;900 xB0;C. Structural changes as a result of heating were characterized using Raman spectroscopy and XRD. Raman13; data showed that TiN, CrN, TiN/CrN, TiAlN, and TiAlN/CrN coatings started to oxidize at 500, 600, 750, 800, and 900 xB0;C, respectively. To isolate the oxidation-induced spectral changes as a result of heating of the coatings in air, samples were also annealed in vacuum at 800 xB0;C under similar conditions. The Raman data of vacuum-annealed coatings showed no phase transformation, and intensity of the optical phonon mode increased and shifted to lower frequencies. The origin of these spectral changes is discussed in terms of defect structure of the coatings. Our results indicate that the thermal stability of nanolayered multilayer coatings is superior to the13; single-layer coatings.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0884291400087197

Raman spectroscopy studies on the thermal stability of TiN, crN, TiAlN coatings and nanolayered TiN/CrN, TiAlN/CrN multilayer coatings

Over the past decades, hard and super hard ceramic coatings have been developed and widely used in various industrial applications Meanwhile, an increasing number of studies have realized that the toughness is just as crucial, if not more, than hardness especially for ceramic coatings However, hardness and toughness do not go naturally hand in hand In other words, hard coatings usually are brittle and less durable while toughened coatings are of lower strength For practical engineering applications, it is more desirable to have coatings with high hardness without sacrificing toughness too much In this article, a review is presented on continuous progress to realize hard-yet-tough ceramic coatings from an angle of hardening as well as toughening

Toward hard yet tough ceramic coatings

An investigation into TiN-coated 316L stainless steel as a bipolar plate material for PEM fuel cells

Electrochemical behavior of single layer CrN, TiN, TiAlN coatings and nanolayered TiAlN/CrN multilayer coatings prepared by reactive direct current magnetron sputtering

Structure, hardness and thermal stability of TiAlN and nanolayered TiAlN/CrN multilayer films

Corrosion behavior of nanolayered TiN/NbN multilayer coatings prepared by reactive direct current magnetron sputtering process

Single layer TiN coatings were prepared on silicon (111) substrates using a multi-target reactive DC magnetron sputtering process at various nitrogen flow rates and substrate biases. TiN coatings prepared at a nitrogen flow rate of 0.6 sccm, a power density of 5.4 W/cm2 and a substrate bias of −275 V, showed a nanoindentation hardness of 3300 kg/mm2, whereas amorphous carbon (a-C) coatings prepared under similar deposition conditions exhibited a hardness of 800 kg/mm2. Subsequently, nanocomposite coatings of TiN/a-C were prepared on silicon (111) and M3 tool steel substrates by rotating the substrate back and forth between the titanium and the graphite targets. The nanocomposite coatings were prepared at various carbon concentrations. Structural characterization of the coatings was done by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The compositions of the coatings were determined using energy dispersive X-ray analysis (EDAX). The nanocomposite coatings exhibited a broad (111) reflection of cubic TiN phase in XRD data. Nanoindentation data showed that about 1.5-μm-thick TiN/a-C nanocomposite coatings exhibited a maximum hardness of 4800 kg/mm2 at a carbon concentration of approximately 17 at.%. The TEM micrographs showed that TiN nanocrystals were embedded in a-C matrix and the average crystallite size was 78 A. The selected area electron diffraction of the nanocomposite coatings showed the presence of both nanocrystalline (TiN) and amorphous (a-C) phases. This was confirmed by high-resolution TEM studies.

M. Surya Prakash

Papers

Structure, hardness and thermal stability of TiAlN and nanolayered TiAlN/CrN multilayer films

Corrosion behavior of nanolayered TiN/NbN multilayer coatings prepared by reactive direct current magnetron sputtering process

Superhard nanocomposite coatings of TiN/a-C prepared by reactive DC magnetron sputtering