Robert R. Aharonov

Properties of chromium nitride coatings deposited by cathodic arc evaporation

Abstract CrN coatings deposited at 200–230°C (low temperature) and 480–540°C (high temperature) onto high speed steel were investigated by determining the microhardness, surface roughness and adhesion, as well as using scanning electron microscopy and X-ray diffractometry. It was found that the coatings deposited at lower temperatures exhibit higher hardnesses than those produced at higher deposition temperatures. Both coatings exhibit good adhesion and a dense structure morphology. Bulk X-ray diffraction studies show that, in both cases, the prevalent crystallographic orientation is [220].

Factors affecting growth defect formation in cathodic arc evaporated coatings

Abstract The origin of the conical features on the surfaces of arc evaporated hard compound coatings was investigated. A simple metallographic technique was employed to show that these conical features are growth defects made of the coating material (TiN in our case) precipitated by macroparticles of the cathode material, and not the macroparticles themselves. The effect of bias voltage characteristics, such as the amplitude (for d.c. voltage), frequency and duty cycle (for pulsed voltage), on the evolution of defects was also investigated. An increase in the amplitude or duty cycle resulted in a decrease in the defect density, Ra and the surface area covered with the defects. A simple explanation for the phenomena observed is suggested.

Investigation of carbon nitride films by cathodic arc evaporation

Presently there is great interest in deposition of the β-phase C3N4 because its predicted hardness and moduli exceed those of diamond. The use of energetic particle beam methods have shown promise in terms of nitrogen incorporation. Energetic and highly ionized beams from cathodic arcs have also proven to be effective in deposition of tetrahedral amorphous carbon (ta-C). In this paper we report on CN films deposited using a carbon arc in nitrogen atmosphere. Films with nitrogen concentration ranging from 17–32% were deposited as a function of nitrogen pressure and substrate temperature. CNx films deposited above room temperature and 1 mTorr (0.013 Pa) of N2 were found to have low stress, indicating the presence of mostly sp2 bonding.

An investigation of the properties of Ti-C:H films

The relationship between deposition parameters and the properties of multilayered Ti-C:H films has been investigated, in particular, the effect of acetylene flow and r.f. bias on the mechanical properties, electrical properties and reflectance of the coating. The coating investigated was a multilayered design with Ti, TiN, TiCN and TiC underlayers; however, this study focuses on the properties of an outer Ti-C:H film, which contains less than 15 at.% titanium. Ti-C:H films with Vickers hardness values ranging from 500 to 1200 Vickers, an elastic modulus from 50 to 110 GPa, specific resistivities approaching 1 GΩ cm and a dielectic constant of 3.2 can be produced depending on the deposition parameters. The coating can be deposited with a low reflectance which is suggested to be an indicator of film composition.

Failure characterization of tools coated with hard compound coatings

Abstract A coating process is usually the last step in the macufacture of many devices used throughout industry. Hard compound coatings such as titanium nitride and chromium nitride have found their use in the area of wear and abrasion resistance. Superior mechanical and chemical coating properties will not protect a tool or component from failing if the substrate material exhibits flawed metallurgy or poor surface finish. In addition, improper substrate cleaning, conditioning or coating application could also be the reason behind the failure. Techniques, such as metallography, electron microscopy, energy-dispersive X-ray spectroscopy, microhardness and adhesion testing may be used to characterize different types of failure. This work presents an approach to failure analysis of coated devices, which is demonstrated in several case studies.