Sialon and Alumina Modified UV-Curable Coatings with Improved Mechanical Properties and Hydrophobicity

Abstract

This article describes the modification of UV-curable coatings with silicon aluminum oxynitride (Sialon) and aluminum oxide (Alu C), which improve the hydrophobicity of the coating surface and the scratch hardness. The contact angle is greater due to surface roughness being enhanced with inorganic fillers. Improved scratch resistance results from the formation of a sliding layer triggered by the diffusion of Sialon or alumina on the coating surface. One can observed an increase in the surface hydrophobicity as well as in the scratch hardness (up to 100%) when small amounts (5 wt.%) of the inorganic compounds are added. Imaging microscopies, i.e., SEM, OM, and AFM (with nanoscopic Young’s modulus determination), revealed the good distribution of both types of fillers in the studied matrix.

Influence of the Addition of Sialon and Aluminum Nitride Fillers on the Photocuring Process of Polymer Coatings

“…The viscosities of the compositions are shown in Figure 2: (a) the BisEA10/Sialon composition; (b) BisEA10/AlN composition (at 25 • C) and (c) the dependence of the viscosity on the filler content at the rotation speed V = 60 rpm. In our previous publication [12], the 1.5 wt.% of the Sialon filler added to the varnishes slightly reduced the viscosity of the composition, the larger amounts of Sialon (3 wt.% and 5 wt.%) increased the viscosity of the composition by 11% and 20% (at 25 • C), respectively, compared to the viscosity of the compositions without the filler. However, it was a mixture of other monomers with a viscosity lower than that in the this publication.…”

“…The viscosity of the composition is crucial in the course of polymerization. Therefore, when preparing the composition of new filler varnishes, it is necessary to pay particular attention to the type of filler and the amount of filler added, to obtain the desired viscosity of the composition [12]. Sialon is a silicon nitride ceramic with a small percentage of aluminum nitride added; therefore, we can say that Sialon are ceramic alloys containing the elements silicon (Si), aluminum (Al), oxygen (O), and nitrogen (N).…”

“…As should be noted, coatings containing Sialon show a slightly better non-wetting property. In consequence, products coated with the varnishes can be used longer and it is easier to remove impurities from them [12]. θW greater than 90°; θW values of the pure coatings are approximately 69°.…”

“…The above-mentioned ceramic materials are commonly used for cutting tools, mechanical seals, heat exchangers, and ingredients for heat engines, generally in the form of monolithic material [8]. Among the various fillers, which are part of the Sialon particles, aluminum nitride (AlN) is an important ceramic material that is in great demand due to its excellent thermal conductivity (82-170 W/mK), electrical resistance (>1014 Ω•cm), as well as its thermal stability, lack of toxicity, silicon-like low coefficient of thermal expansion, good chemical stability and high hardness [9][10][11][12].…”

“…Although some studies have investigated the formation of UV-induced inorganic coatings, the effect of the filler on the polymerization rate of these systems was often overlooked. In our previous work [12], we used sialon (and aluminum oxide) as fillers for polymer coatings. We noticed that the addition of small amounts (5 wt.%) of inorganic compounds improved the hydrophobicity of the polymer coating surface, scratch resistance, scratch hardness, and surface hydrophobicity.…”