Chapter 17. Compressive Strength and Creep Behavior of a Magnesium Chromite Refractory

  1. William Smothers
  1. Ralph F. Krause Jr.

Published Online: 28 MAR 2008

DOI: 10.1002/9780470320310.ch17

Applications of Refractories: Ceramic Engineering and Science Proceedings, Volume 7, Issue 1/2

Applications of Refractories: Ceramic Engineering and Science Proceedings, Volume 7, Issue 1/2

How to Cite

Krause, R. F. (1986) Compressive Strength and Creep Behavior of a Magnesium Chromite Refractory, in Applications of Refractories: Ceramic Engineering and Science Proceedings, Volume 7, Issue 1/2 (ed W. Smothers), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470320310.ch17

Author Information

  1. National Bureau of Standards Gaithersburg, MD 20899

Publication History

  1. Published Online: 28 MAR 2008
  2. Published Print: 1 JAN 1986

ISBN Information

Print ISBN: 9780470374443

Online ISBN: 9780470320310

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Keywords:

  • magnesium chromite;
  • cross-sectional slice;
  • alumina tube;
  • acceleration of gravity;
  • coefficients

Summary

The compressive strength of a magnesium chromite refractory in nitrogen was measured by rapidly loading specimens to failure at several temperatures up to 1600OC. Strength retrogression was observed at temperatures above 1200°C. The creep behavior of the refractory in nitrogen was measured as a function of compressive stress in the range from 1.4 to 5. 6 MPa and as a function of temperature in the range from 1300 to 1600°C. A nitrogen atmosphere was used to suppress distillation of CrO3 Generally, the experiments were terminated when the specimens sustained from 0.01 to 0.02 creep strain. The creep strain (ϵ) at a given stress (o) and a given absolute temperature (T) was represented by the following function of time (t), ϵ = C tm, where (C) depends on stress and temperature. The time exponent (m) was evaluated as less than unity, indicating a strain-hardening model, and was independent of stress and temperature within the precision of measurements. The creep strain rate was represented by the relationship, (dϵ/dt) = A (1–1/m) an exp (-Q/RT), in which (R) is the molar gas constant. The material constant (A), the stress exponent (n), and the activation energy (Q) were evaluated from a least squares fit of this relationship to the creep data at constant strain.