Nm For Coatings Research Articles

Structure and Properties of ZrON Coatings Synthesized by Cathodic Arc Evaporation.

The transition metal oxynitrides are a coating material with decorative features due to their adjustable color and good mechanical properties. The purpose of the research was to study the effect of the relative oxygen concentration O2(x) = O2/(N2 + O2) in particular on adhesion, but also on the color, structural and mechanical properties of ZrON coatings synthesized by cathodic arc evaporation on HS6-5-2 steel substrates. The surface morphology, phase and chemical composition and mechanical properties were determined using scanning electron microscopy, X-ray diffraction, wavelength dispersive X-ray spectroscopy, nanoindentation and scratch test. It was found that color of the coatings changed from light yellow for ZrN first to gold and then to graphite for Zr-O phase with increase of oxygen concentration. X-ray diffraction patterns showed that the phase separation of ZrN and ZrO2 occurred for about 35 at.% of oxygen in the coating. Increase in oxygen concentration in the coatings led to decrease in crystallite size from about 20 nm for ZrN to about 5 nm for coatings with about 35 at.% of oxygen and about 25 at.% of nitrogen. An increase in hardness from about 26 GPa for ZrN to about 30 GPa for coating with small concentration of oxygen (about 9 at.%) and then decrease to about 15 GPa was observed. Adhesion of Zr-O-N coatings demonstrated strong dependence on oxygen concentration. Critical load for ZrN is about 80 N and decreases with oxygen concentration increase to about 30 N for ZrO2.

Influence of oblique angle deposition on Cu-substituted hydroxyapatite nano-roughness and morphology

In this work, we study the effect of RF magnetron oblique angle deposition (OAD) on morphology, structure, and elemental composition of as-deposited and heat-treated Cu containing calcium phosphates. The control over the surface morphology and nano roughness provided by OAD is of great interest as both Mesenchymal Stem Cells and various types of bacteria respond strongly to nanoscale topography. A Cu substituted hydroxyapatite target was used to deposit coatings on the surface of titanium (Ti) and silicon (Si) substrates. The samples were placed at an oblique angle of 80° relative to the surface of the sample holder and in a normal configuration with respect to the flux direction and, therefore, parallel to the target. The dense homogeneous coatings with globular surface features deposited at normal flux incidence (NFI) configuration changed to elliptical, highly oriented structures with the direction dictated by the atomic shadowing effect when the substrate was deposited at an oblique angle. As-deposited thin films were subjected to post-deposition-heat-treatment at 700 °C in an Ar atmosphere. This led to a drastic change in the surface morphology and, namely, lost the directionality of the nanostructures. According to the X-ray diffraction data, the samples deposited obliquely showed preferential growth in the (002) plane and lower internal stress, than samples coated at NFI for both the Si and Ti substrates. The RMS roughness of the films deposited obliquely on Si was twice that of the films deposited at NFI (860 ± 80 pm and 408 ± 60 pm, respectively). However, it was not the case for the Ti substrate, the RMS roughness decreased from 42 ± 4 nm for coatings deposited at normal flux geometry to 33 ± 2 nm for coatings deposited obliquely. The heat-treatment of the samples deposited at 80° resulted in a significant increase in the surface roughness: 8 ± 0.7 nm for Si and 71 ± 4 nm for Ti substrates. The obtained results demonstrate that the oblique angle deposition can be used to fabricate nano-rough surface morphologies.

Mechanical properties and epitaxial growth of TiN/AlN superlattices

TiN/AlN superlattice coatings combine the superlattice effect and the outstanding properties of AlN in its non-equilibrium face-centred cubic (NaCl-type, rs) structure. In comparison with their non-layered counterparts, the superlattice films exhibit superior and strongly bilayer-period-dependent mechanical properties. Here we analyse the structure and mechanical properties of superlattices with AlN layer thicknesses of 0.9, 1.2, and 1.5 nm and different TiN layer thicknesses. We found that the maximum AlN layer thickness, up to which AlN can be fully stabilized in its metastable rs structure, depends on the substrate material and is at least 1.5 nm for coatings on MgO (100) and 0.9 nm for the coatings grown on Si (100) or Al2O311¯02. Our data also show that with increasing thickness of the template layer, the crystallization of AlN in the stable wurtzite structure is favoured. TiN/AlN superlattice coatings on MgO (100) exhibit the highest hardness values, peaking at 37.0 ± 0.5 GPa for AlN layer thicknesses of 0.9 nm and a bilayer period of 2.5 nm. Films with ultra-small bilayer periods exhibit high hardness combined with low values of elastic modulus suggesting a high elastic-strain-to-failure for these coatings. The highest toughness was found for superlattice films grown on MgO (100), scaling inversely with the bilayer period.

SiNx coatings deposited by reactive high power impulse magnetron sputtering: Process parameters influencing the residual coating stress

The residual coating stress and its control is of key importance for the performance and reliability of silicon nitride (SiNx) coatings for biomedical applications. This study explores the most important deposition process parameters to tailor the residual coating stress and hence improve the adhesion of SiNx coatings deposited by reactive high power impulse magnetron sputtering (rHiPIMS). Reactive sputter deposition and plasma characterization were conducted in an industrial deposition chamber equipped with pure Si targets in N2/Ar ambient. Reactive HiPIMS processes using N2-to-Ar flow ratios of 0 and 0.28–0.3 were studied with time averaged positive ion mass spectrometry. The coatings were deposited to thicknesses of 2 μm on Si(001) and to 5 μm on polished CoCrMo disks. The residual stress of the X-ray amorphous coatings was determined from the curvature of the Si substrates as obtained by X-ray diffraction. The coatings were further characterized by X-ray photoelectron spectroscopy, scanning electron microscopy, and nanoindentation in order to study their elemental composition, morphology, and hardness, respectively. The adhesion of the 5 μm thick coatings deposited on CoCrMo disks was assessed using the Rockwell C test. The deposition of SiNx coatings by rHiPIMS using N2-to-Ar flow ratios of 0.28 yield dense and hard SiNx coatings with Si/N ratios <1. The compressive residual stress of up to 2.1 GPa can be reduced to 0.2 GPa using a comparatively high deposition pressure of 600 mPa, substrate temperatures below 200 °C, low pulse energies of <2.5 Ws, and moderate negative bias voltages of up to 100 V. These process parameters resulted in excellent coating adhesion (ISO 0, HF1) and a low surface roughness of 14 nm for coatings deposited on CoCrMo.

Structure of CrON coatings formed in vacuum arc plasma fluxes

Abstract Cr–O–N coatings were formed by cathodic arc evaporation at different O 2 / (N 2 + O 2 ) relative oxygen concentrations onto HS6-5-2 (DIN standard) steel substrates. The chemical and phase composition, surface morphology on the as-deposited coatings were investigated by Wavelength Dispersive Spectrometry, X-ray Diffraction, Atomic Force Microscopy, Scanning Electron Microscopy and Raman Spectroscopy. The coatings deposited in pure nitrogen atmosphere had a cubic CrN structure. Structural properties of the coatings synthesized in mixed oxygen and nitrogen atmosphere depended strongly on the relative oxygen concentration. High relative oxygen concentration caused amorphization of the coating. XRD diffraction lines were shifted and broadened, indicating increasing stress and decreasing mean crystallite size, from 109 nm for coatings deposited at relative oxygen concentration equal 0% to 23 nm at 20%. The coatings formed at 50% relative oxygen concentration had a rhombohedral Cr 2 O 3 structure with a grain size of about 11 nm and lattice distortion of about 2%. Increasing the relative oxygen concentration also increased the surface roughness and the fraction of the surface rate covered by macroparticles.

Room Temperature Processed Hard Easy Clean Coating Using Ammonia Treatment

In this paper we report the fabrication of hydrophobic hard coatings using sol-gel processing and cured at room temperature by an ammonia-assisted process. The coating thickness can be tuned from several hundreds of nanometer to several microns. These coatings show both high transparency (better than PMMA or glass substrates) and high hardness (pencil hardness 2H-4H on PMMA). The coatings are very smooth with surface roughness Ra less than 2 nm for coatings with different thicknesses from 200 nm to 2 m. The water contact angle (WCA) of the coating is about 115 to 120o and the sliding angle for a 20 l water drop is less than 10o. The advantage of this process is the ease for larger area application and especially suitable for plastic surface treatment due to the low temperature curing process.

Chromate conversion coating on Al–0.2 wt.% Fe alloy

SEM and TEM investigations revealed that the chromate coating developed rapidly over the macroscopic alloy surface. The coating thickness increased over the immersion period employed in this study and was about 50 nm and 200 nm for coatings formed after 30 s and 120 s respectively. The coating is composed of chromium compounds with aluminium compounds probably concentrated at the alloy/coating interface.

Microstructure of Physical Vapour Deposited Ti-Si-N Coatings

AbstractThe influence of Si on the microstrucure of Ti-Si-N coatings was studied, since it controls the mechanical properties of the coatings. At low Si-contents columnar {111}-textured TiN grains form. Increasin the Si-content to >4at% causes a transition to equiaxed {200}-textured TiN grains. The equiaxed TiN grains reveal grain diameters of ∼6 nm for coatings containing 11 at% Si.

Laser-damage-resistant transparent conductive indium tin oxide coatings

Transparent conductive coatings of In1.9Sn0.1O3 have been made on fused silica which exhibit damage thresholds of 2.2 and 3.1 J/cm2 for 0.15- and 1-nsec Nd : glass laser pulses, respectively. The coatings were made by reactive sputtering in an rf diode system. Coating absorption detected spectrophotometrically was less than 1% (∼300 cm−1) near 1064 nm for coatings with in-plane resistivities of 0.017 and 0.55 Ω cm. An important potential application for such coatings is as the electrode for electro-optic shutters based on the longitudinal Pockels effect which are used in high-energy laser systems.