Microstructure and analytic equation of conical aggregate in iridium coating prepared by double glow plasma

Abstract

Dense and uniform Iridium (Ir) coating was deposited on the surface of the graphite substrate by double glow plasma. The phase identification and the morphology of the coating were examined by X-ray diffraction and scanning electron microscopy, respectively. The coating was composed of uniformly distributed regularly conical aggregates which were composed of the columnar crystals with a preferential (220) orientation. The preferential orientation was regardless of different deposition parameters and substrate properties. The analytic equation of the generatrix of the conical aggregate was determined by measuring its external dimensions. The deposition rate of the coating was up to 20 mm h 21 . The gap appeared within the fracture surface of the coating could result from the shadow effect of the conical aggregate. Because of the poor wetting between Ir element and C element, Ir coating grew according to the Stranski-Krastanov model.

Study on Titanized Layer Microstructure of T10 Steel by Double Glow Plasma Surface Alloying Technique

“…Compared with other surface modification methods, the advantage of this technique is that a gradient diffusion layer can be obtained with enough thickness and good adherence between modified layer and substrate [5,6], which significantly improves the surface properties of materials. The DGPSA has successfully realized obtaining various mono-element and multi-elements alloying layers [7][8][9]. Nowadays, current researches have also more focused on some basic problems, such as the relationship between the layer thickness and different holding time, temperature, or element distribution in the modified layer [10][11][12][13][14][15].…”

Corrosion properties of Pt coatings by double glow plasma

“…12 The general advantages of this technique include low operating cost, low pollution, safer and more stable, high deposition rate, good coating uniformity, controllability of the coating thickness and strong adhesion to complex shaped substrates. 13 Generally, the microstructure of the coating grown in the sputtering process was heavily dependent on the gas pressure and the substrate temperature. 14 Furthermore, the structure of the coating could influence properties of the coating.…”

“…The adhesion of the Pt coating to the substrate was ∼60 N. Double glow plasma technique can be used for almost any solid metallic element for surface alloying to metallic substrates 12. The general advantages of this technique include low operating cost, low pollution, safer and more stable, high deposition rate, good coating uniformity, controllability of the coating thickness and strong adhesion to complex shaped substrates 13. Generally, the microstructure of the coating grown in the sputtering process was heavily dependent on the gas pressure and the substrate temperature 14.…”

Study on Iridium Coating Produced by Double Glow Plasma

“…Iridium (Ir) has a high melting point (2447 o C), an oxygen permeability less than 10 -14 g•cm -1 •s -1 at 2200 o C, high chemical compatibility, superior oxidation resistance and the absence of carbide below the eutectic temperature of 2280 o C [1,2]. Therefore, the Ir acts as an effective diffusion barrier for inward oxygen and outward carbon.…”