Preparation, surface characterization, and water resistance of silicate and sol-silicate inorganic–organic hybrid dispersion coatings for wood

Cheumani-Yona, Arnaud Maxime (avtor), Žigon, Jure (avtor), Ngueteu Kamlo, Alexis (avtor), Pavlič, Matjaž (avtor), Dahle, Sebastian (avtor), Petrič, Marko (avtor)

The purpose of this study was to comparatively investigate the behavior of silicate and sol-silicate coatings non-modified or modified with an organosilane on wood and on wood precoated with silica-mineralized primers. Adhesion strength, morphology, and water permeability and related damages were studied to evaluate the possibility of utilizing such inorganic-based coating systems for durable protection of wood without or with relatively cheap and water-borne primers. Potassium silicate and potassium methylsiliconate aqueous solutions and a colloidal silica were used for the preparation of the coatings. The white coating paints were brushed on beech wood substrates at a rate of 220 g·m$^{−2}$. The coatings exhibited good coverage ability. The pull-off adhesion strength values appeared to be related to pH following a polynomial law. The adhesion strength for the silicate coatings were adequate (above 3 MPa and up to 5 MPa) for wood, whereas the values for the sol-silicates were too low for practical applications. The adhesion values were in general higher for the samples cured in a climate room (23 ± 3 °C and 75 ± 2% relative humidity) than the samples cured in the ambient atmosphere of the laboratory (23 ± 3 °C and 25 ± 5% relative humidity). The presence of microdefects (cracks, holes) was revealed in the coating layers by optical and scanning electron microscopy. The surface roughness parameters assessed by confocal scanning laser microscopy were dependent on the magnification applied for their measurement. The arithmetic average roughness S$_a$ was between 5 µm and 10 µm at magnification 5× and between 2.5 µm and 10 µm at magnification 20×. The maximum peak-to-valley height S$_z$ confirmed the presence of open pores emerging through the coatings. The open pores constitute free pathways for water ingress through the coatings, and could explain the high water absorption of the coatings including the methysiliconate-containing silicate coating and despite the relatively high water contact angle and low wettability exhibited by this sample. The post-application of a hydrophobizing solution containing hexadecyltrimethoxysilane and dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride considerably reduced the water permeability, while application of nanosilica-containing organic primers increased the adhesion for the coatings. Silicate coatings with adhesion great enough and resistance against water damages can be generated on wood even without a primer using low silica-to-alkali ratio binders and an organosilane additive. The sol-silicate coatings appear to be applicable only with a primer. The improvement of the paint formulations to control the formation of microcracks and open pores could be useful to reduce the liquid water permeability and increase durability. Otherwise, the application of a hydrophobizing treatment can be used for this purpose.

• Jezik: Angleški jezik
• Ključne besede: wood, silicate, sol-silicate, coating, roughness, adhesion
• Vrsta gradiva: Članek v reviji
• Tipologija: 1.01 - Izvirni znanstveni članek
• Organizacija: BF - Biotehniška fakulteta
• Status publikacije: Objavljeno
• Različica publikacije: Objavljena publikacija
• Leto izida: 2021
• Št. strani: 23 str.
• Številčenje: Vol. 14, iss. 13, art. 3559
• PID: 20.500.12556/RUL-135598
• UDK: 630*8
• ISSN pri članku: 1996-1944
• DOI: 10.3390/ma14133559
• COBISS.SI-ID: 68262659
• Datum objave v RUL: 22.03.2022

Gradivo je del revije

• Naslov: Materials
• Skrajšan naslov: Materials
• Založnik: Molecular Diversity Preservation International
• ISSN: 1996-1944
• COBISS.SI-ID: 33588485

Licence

• Licenca: CC BY 4.0, Creative Commons Priznanje avtorstva 4.0 Mednarodna
• Povezava: http://creativecommons.org/licenses/by/4.0/deed.sl
• Opis: To je standardna licenca Creative Commons, ki daje uporabnikom največ možnosti za nadaljnjo uporabo dela, pri čemer morajo navesti avtorja.
• Začetek licenciranja: 01.07.2021

Sekundarni jezik

• Jezik: Slovenski jezik
• Ključne besede: les, silikat, premazi, hrapavost, adhezija

Projekti

• Financer: ARRS - Agencija za raziskovalno dejavnost Republike Slovenije
• Številka projekta: N4-0117
• Naslov: Silikatni premazi za les z odlično trajnostjo

• Financer: ARRS - Agencija za raziskovalno dejavnost Republike Slovenije
• Številka projekta: P4-0015
• Naslov: Les in lignocelulozni kompoziti