Influence of KMnO4 Concentration on Infrared Emissivity of Coatings

On TC4 Alloys by Micro-Arc Oxidation (Materials EISSN 1996-1944)

Abstract:

Fig 8. Infrared emissivity curves of the MAO ceramic coatings with different KMnO4 concentrations within a waveband of 5–20 μm.[/caption]

Ceramic coatings with high emissivity were fabricated on TC4 alloys by micro-arc oxidation technique (MAO) in mixed silicate and phosphate electrolytes with varying KMnO₄ addition.

The microstructure, phase and chemical composition were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), and the infrared emissivity of the MAO coatings was measured in a waveband of 5–20 μm.

The results show that the thickness of the coatings increased with the addition of KMnO₄, but the roughness of the coatings first decreased and then increased slightly due to the inhibitory effect of KMnO₄ on Na₂SiO₃ deposition.


The main phase composition of the coatings was anatase and rutile TiO₂, amorphous form of SiO₂ and MnO₂. The infrared emissivity value of the coatings strongly depended on KMnO₄ concentration, the coating formed at the concentration of 0.8 g/L KMnO₄ reached the highest and an average of up to 0.87 was observed.

Authors:

Guangrui Gao ^1,2,3,*, Ying Li ^1,*, Chaozhong Li ³, Dan Hu ³, Zhengxian Li ² and Zhengping Xi ¹

1 School of Metallurgy, Northeastern University, Shenyang 110819, China

² Research Institute of Corrosion and Protection, Northwest Institute for Nonferrous Metal Research, Xi’an 710016, China

³Xi’an Surface Material Protection Co., Ltd., Xi’an 710016, China

*Correspondence: Tel.: +86-135-7149-0985 (G.G.); +86-131-9008-6601 (Y.L.)

Received: 29 September 2017 / Accepted: 9 November 2017 / Published: 13 November 2017

Materials 2017, 10(11), 1301; doi:10.3390/ma10111301

Source: http://www.mdpi.com/1996-1944/10/11/1301/htm