Pre eutectic densification in MgF/sub 2/ - CaF/sub 2/

Technical Report · Fri May 01 04:00:00 EDT 1981

OSTI ID:6469442

Hu, S C

Three sintering methods were used: (a) Arrested zone sintering, (b) constant heating rate sintering, and (c) constant temperature sintering. Microstructural evolution and shrinkage vs temperature behaviour were studied. It was found that the sintering rate of MgF/sub 2/ was enhanced by CaF/sub 2/ eutectic additive, and that the enhancement of sintering started at about 200/sup 0/C below the eutectic temperature. The effectness of CaF/sub 2/ saturates at about 1 wt%. By comparing the diffusivities obtained from diffusion experiment and constant temperature sintering experiment, it is concluded that the enhanced pre-eutectic densification kinetics result from increased solid state grain boundary transport due to eutectic forming phase. The possible effect of oxidation on the eutectic temperature of CaF/sub 2/ - MgF/sub 2/ during the experiment has been verified to strengthen the conclusion that solid state mass transport causes the enhancement. Auger analysis shows that Ca/sup +2/ is enriched at grain boundaries in a layer with a thickness of about 100 A. 28 figures, 9 tables.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6469442
• Report Number(s): LBL-12849; ON: DE81027553
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360601* -- Other Materials-- Preparation & Manufacture
ALKALINE EARTH METAL COMPOUNDS
AUGER ELECTRON SPECTROSCOPY
CALCIUM COMPOUNDS
CALCIUM FLUORIDES
CALCIUM HALIDES
CHEMICAL REACTIONS
CRYSTAL STRUCTURE
ELECTRON SPECTROSCOPY
EUTECTICS
FABRICATION
FLUORIDES
FLUORINE COMPOUNDS
GRAIN BOUNDARIES
HALIDES
HALOGEN COMPOUNDS
KINETICS
MAGNESIUM COMPOUNDS
MAGNESIUM FLUORIDES
MICROSTRUCTURE
OXIDATION
SINTERING
SPECTROSCOPY