Abstract
Compressive creep of five commercially-available brands of CaO/SiO2-containing MgO refractories was measured over a temperature range of 1400-1550°C and compressive stresses of 0.10-0.30 MPa. All brands had a MgO content greater than 96 wt%, a CaO/SiO2 wt% ratio equal to or greater than 1.9, and a firing temperature greater than 1535°C. The more creep resistant brands were observed to have a combination of: (1) a larger average grain size and wider grain size distribution, (2) a low iron content, and (3) an absence of CaO-MgO-SiO2 compounds. Creep-stress exponents for three of the five brands indicated their creep was rate-controlled by diffusion, and their activation energy values indicated that creep was accommodated by grain boundary sliding through viscous flow of the calcium silicate grain-boundary phase. Two brands exhibited dramatic time-hardening behavior which resulted in their creep not being well-represented by the power-law creep formulation. The observed attributes among the brands were combined and a hypothetical CaO/SiO2-containing MgO refractory is proposed.
Original language | English |
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Pages (from-to) | 215-227 |
Number of pages | 13 |
Journal | Journal of Materials Science |
Volume | 34 |
Issue number | 2 |
DOIs | |
State | Published - 1999 |
Externally published | Yes |
Funding
⁄Research sponsored by the U.S. Department of Energy, Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Transportation Technologies, as part of the High Temperature Materials Laboratory User Program under Contract DE-AC05-96OR22464, managed by Lockheed Martin Energy Research Corporation. zMember, American Ceramic Society.