• Blanco, B. Agea
• Blaess, C.
• Müller, R.
• Reinsch, S.
• Brauer, D.

Abstract

<jats:p>Sintering and foaming of barium and calcium silicate glass powder compacts have been studied for different powder milling. Sintering was measured by means of heating microscopy backed up by XRD, DTA, Vacuum Hot Extraction (VHE) and electron microscopy. Foaming intensity strongly increased with decreasing glass particle size. Although powder compacts were uniaxially pressed and sintered in ambient air, foaming was affected by the milling atmosphere and most intensive for milling in CO2. Conformingly, VHE studies revealed that foaming of fully sintered samples was mainly driven by CO2, even for powders milled in technical air, Ar and N2. Prolonged storage of air milled barium silicate glass powders in ambient air before pressing and sintering caused further increase of foaming intensity. These findings indicate that carbonaceous species are preferentially trapped to or close beneath the powder surface during milling and later storage. The temperature range of CO2 degassing from fully sintered barium and calcium silicate glass powder compacts fits the temperature ranges of decomposition of BaCO3 and CaCO3 mix-milled with the respective barium and calcium silicate glass powders.</jats:p>

Topics

• surface
• x-ray diffraction
• extraction
• grinding
• glass
• glass
• milling
• electron microscopy
• Calcium
• degassing
• decomposition
• sintering
• differential thermal analysis
• Barium