TY - JOUR

T1 - Foaming Species and Trapping Mechanisms in Barium Silicate Glass Sealants

AU - Müller, Ralf

AU - Behrens, Harald

AU - Agea-Blanco, Boris

AU - Reinsch, Stefan

AU - Wirth, Thomas

N1 - Funding Information: The authors grateful acknowledge experimental support by colleagues I. Feldmann (scanning electron microscope), A. Wagner (X‐ray photoelectron spectroscopy), and A. Kohl (attenuated total reflectance accessory–FTIR). The authors finally acknowledge financial support by Erasmus Lifelong Learning Programs for B. Agea‐Blanco.

PY - 2022/6/21

Y1 - 2022/6/21

N2 - Barium silicate glass powders 4 h milled in CO2 and Ar and sintered in air are studied with microscopy, total carbon analysis, differential thermal analysis (DTA), vacuum hot extraction mass spectroscopy (VHE-MS), Fourier-transformed infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary-ion mass spectrometry (TOF−SIMS). Intensive foaming of powder compacts is evident, and VHE studies prove that foaming is predominantly caused by carbonaceous species for both milling gases. DTA shows that the decomposition of BaCO3 particles mix-milled with glass powders occurs at similar temperatures as foaming of compacts. However, no carbonate at the glass surface could be detected by FTIR spectroscopy, XPS, and TOF−SIMS after heating to the temperature of sintering. Instead, CO2 molecules unable to rotate identified by FTIR spectroscopy after milling, probably trapped by mechanical dissolution into the glass bulk. Such a mechanism or microencapsulation in cracks and particle aggregates can explain the contribution of Ar to foaming after intense milling in Ar atmosphere. The amount of CO2 molecules and Ar, however, cannot fully explain the extent of foaming. Carbonates mechanically dissolved beneath the surface or encapsulated in cracks and micropores of particle aggregates are therefore probably the major foaming source.

AB - Barium silicate glass powders 4 h milled in CO2 and Ar and sintered in air are studied with microscopy, total carbon analysis, differential thermal analysis (DTA), vacuum hot extraction mass spectroscopy (VHE-MS), Fourier-transformed infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary-ion mass spectrometry (TOF−SIMS). Intensive foaming of powder compacts is evident, and VHE studies prove that foaming is predominantly caused by carbonaceous species for both milling gases. DTA shows that the decomposition of BaCO3 particles mix-milled with glass powders occurs at similar temperatures as foaming of compacts. However, no carbonate at the glass surface could be detected by FTIR spectroscopy, XPS, and TOF−SIMS after heating to the temperature of sintering. Instead, CO2 molecules unable to rotate identified by FTIR spectroscopy after milling, probably trapped by mechanical dissolution into the glass bulk. Such a mechanism or microencapsulation in cracks and particle aggregates can explain the contribution of Ar to foaming after intense milling in Ar atmosphere. The amount of CO2 molecules and Ar, however, cannot fully explain the extent of foaming. Carbonates mechanically dissolved beneath the surface or encapsulated in cracks and micropores of particle aggregates are therefore probably the major foaming source.

KW - foaming

KW - glass powder

KW - milling

KW - sintering

UR - http://www.scopus.com/inward/record.url?scp=85111570790&partnerID=8YFLogxK

U2 - 10.1002/adem.202100445

DO - 10.1002/adem.202100445

M3 - Article

AN - SCOPUS:85111570790

VL - 24

JO - Advanced engineering materials

JF - Advanced engineering materials

SN - 1438-1656

IS - 6

M1 - 2100445

ER -