Sinter-crystallisation kinetics of a SiO–AlO–CaO–MgO–SrO glass-ceramic glaze

Improvement of the mechanical and aesthetic properties of a coating by inkjet technology

“…In contrast, the surface obtained on printing ink at 800 dpi onto the unfired glaze substrate was made up of small acicular crystals of anorthoclase, partly embedded in the glass matrix (Figure 2), which was consistent with previous studies. 5,6 The microstructure of the resulting fired surfaces after ink application of 400 and 600 dpi, respectively, was similar to that of the application at 800 dpi, but with larger glassy areas.…”

“…An ink was applied by inkjet technology onto a glaze substrate made up of a commercial glaze containing a frit and other crystalline raw materials (zircon, nepheline, potassium feldspar, kaolin, and quartz), prepared by wet milling (Table 1). The ink consisted of a glaze that contained 92% by weight of a frit based on the system SiO 2 -Al 2 O 3 -MgO-CaO-SrO, which had previously been studied, 5,6 and 8% by weight kaolin. The ink was prepared according to the appropriate technical specifications for DIMATIX 1024 and XAAR 1002 printhead applications.…”

“…In previous papers, the sinter-crystallization of a glaze almost entirely made up of an anorthoclase-devitrifying strontium frit was studied, it is verified that, when frit particle size was smaller than 1 µm (particle size used for inkjet application), a glass-ceramic material with no apparent porosity, containing abundant small-sized crystals, was obtained. 5,6 Furthermore, as surfaces displaying such characteristics have good mechanical properties 7,8,9,10 and a silky matt appearance, stemming precisely from the abundance of small crystals, and as inkjet application enables obtainment of homogeneous coatings using just 50 g/ m 2 ink laydown, a study was undertaken to examine the feasibility of using the inkjet technique to enhance the mechanical properties and surface appearance of a substrate (a traditional glaze) on application of a glaze or frit (as ink) that yielded an appropriate fired microstructure (surface coated with small crystals, with no porosity). The effect of the applied amount of ink (dpi), made up of the above Sr frit, on the depth profile of the resulting fired coating, its microstructure, surface roughness, and mechanical characteristics was determined.…”

“…In every case, the Na 2 O concentration was very similar to that of the fired glaze substrate, which indicates considerable diffusion of Na + from the glaze substrate to the ink-containing coating surface, followed by its incorporation into the anorthoclase structure during crystallization. 5 Indeed, in practically homogeneous glasses, the glass surface (glass skin) has been verified to contain a greater number of small alkali cations than the rest of the glass, as their diffusivity is higher than that of other cations. 15 The micrograph of the fired glaze substrate surface (Figure 2) shows the presence of groups of plagioclase crystals (which formed during firing), residual zircon (introduced as raw material), and glassy phase, identified in the XRD diffractogram (Figure 3).…”

“…Finally, K 2 O and ZnO content in the ink-containing coating surface decreases slightly with dpi and is lower than that of the fired glaze substrate surface and of the ink, as K + and Zn 2+ incorporation into the anorthoclase structure is very low. 5 F I G U R E 2 Surface backscattered SEM micrographs of the fired glaze substrate and coatings containing an ink application at 400, 600, and 800 dpi, respectively F I G U R E 3 XRD diffractogram of the unfired and fired (1200°C) glaze substrate | 941 AMORÓS et Al.…”