Foaming Species and Trapping Mechanisms in Barium Silicate Glass Sealants

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