Hybrid SiO2–ZrO2 coatings for restoring and repairing glasses damaged by sandblasting

Àyadi, A.; Bouaouadja, N.; Durán, Alicia; Castro, Yolanda

doi:10.1016/j.ceramint.2020.01.067

Cited by 6 publications

(4 citation statements)

References 33 publications

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“…This is observed on samples of S25CRX 12 powders sintered at 1330 • C, S25CRX14 sintered at 1330 • C and on S30CR sintered at 1290 • C (Figure 9). This behavior can be linked to a decrease in the effect of sharp-bump defects, which became more spherical, as observed by Ayadi et al [26] for glasses. It should be useful to make some SEM observations in order to specify this point.…”

Section: Resultssupporting

confidence: 57%

“…This suggests that the chemical composition of the sand is not pure, and it may contain silica (transparent) and silica mixed with other metal oxides. Sand microhardness, determined in a previous study [26] (under a load of 0.6 N for a batch of 30 particles), is 14.49 ± 3.28 GPa. The sand particles of the desert region of Ouargla have wide particle size distribution.…”

Section: Microscopic Observationsmentioning

confidence: 77%

“…This can be attributed to the formation of large defects like chipping, as indicated by several studies [35] which report that after sandblasting transparent samples such as glasses or transparent ceramics, material removal takes place by formation and propagation of lateral cracks which develop into chipping. Evenly, increasing surface reflection can also be a contributing factor to the decrease in optical transmission [26]. Table 8 presents the roughness values Ra of the spinel samples in the pristine, sandblasted and then coated states.…”

Section: Resultsmentioning

confidence: 99%

“…Indeed, sol-gel coatings can penetrate into the micro-defects and defects generated during sandblasting by filling them, adding an improvement in the morphology of the non-eroded zone. Previous results have shown that the coating heals defects in the pristine surface, thereby decreasing light reflection [26]. To better explain the restoration of surface roughness, an atomic force microscopy study was carried out.…”

Section: Resultsmentioning

confidence: 99%

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Improving the Transparency of a MgAl2O4 Spinel Damaged by Sandblasting through a SiO2-ZrO2 Coating

Zegadi,

Ayadi,

Khellaf

et al. 2024

Ceramics

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Transparent materials in contact with harmful environments such as sandstorms are exposed to surface damage. Transparent MgAl2O4 spinel used as protective window, lens or laser exit port, among others, is one of the materials affected by natural aggressions. The impact of sand particles can cause significant defects on the exposed surface, thus affecting its optical and mechanical behavior. The aim of this work is to improve the surface state of a spinel damaged surface by the deposition of a thin layer of SiO2-ZrO2. For this purpose, spinel samples obtained from different commercial powders sintered by Spark Plasma Sintering were sandblasted and further coated with a SiO2-ZrO2 thin layer. The coating was successfully synthesized by the sol/gel method, deposited on the sandblasted samples and then treated at 900 °C, reaching a final thickness of 250 nm. The results indicated that sandblasting significantly affects the surface of the spinel samples as well as the optical transmission, confirmed by UV-visible spectroscopy and profilometry tests. However, the deposition of a SiO2-ZrO2 coating modifies the UV-visible response. Thus, the optical transmission of the S25CRX12 sample presents the best transmission values of 81%, followed by the S25CRX14 sample then the S30CR sample at 550 nm wavelength. An important difference was observed between sandblasted samples and coated samples at low and high wavelengths. At low wavelengths (around 200 nm), sandblasting tends to improve significantly the transmission of spinel samples, which exhibit a low transmission in the pristine state. This phenomenon can be attributed to the healing of small superficial defects responsible for the degradation of transmission such as pores or flaws. When the initial transmission at 200 nm is high, the sandblasting worsens the transmission. Sandblasting reduces slightly the transmission values for long wavelengths due to the formation of large superficial defects like chipping by creation and propagation of lateral cracks. The coating of the sandblasted samples exhibits some healing of defects induced by sandblasting. The deposition of the SiO2-ZrO2 layer induces a clear increase in the optical transmission values, sometimes exceeding the initial values of the transmission in the pristine state.

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Section: Resultssupporting

confidence: 57%

Section: Microscopic Observationsmentioning

confidence: 77%