Sintering stress and microstructure in ceramic powder compacts

Technical Report · Wed Aug 01 00:00:00 EDT 1990

DOI:https://doi.org/10.2172/6388375· OSTI ID:6388375

Chu, May-Ying ^[1]

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1. Lawrence Berkeley Lab., CA (USA) California Univ., Berkeley, CA (USA). Dept. of Materials Science and Mineral Engineering

The behavior of the sintering stress and microstructure during sintering is studied under various thermal and physical conditions. Specifically, the study includes sintering under isothermal or constant heating rate conditions; and altering the starting compact structure by pre-coarsening to increase the particle size, or by compaction to increase the starting density. Loading dilatometry is used to measure the ratio of the densification strain rate to the creep strain rate and the continuous shrinkage history of the systems. The data show that the ratio of the densification to the creep strain rate is remarkably constant within a wide temperature range for densification, from the earliest stages of densification to at least the onset of the final stage. As a consequence, the sintering stress, which is proportional to the strain rate ratio, is nearly independent of sintered density or of temperature. Analysis leads to a simple method for determining the simultaneous densification strain rate over the creep strain rate ratio. A rigorous densification strain rate equation is derived for a model system. The constant sintering stress allows progress on formulating a sintering equation to predict the densification behavior of powder compacts. Analysis of dilatometry data from compacts sintered at various heating rates, and of numerical computations, indicate the need to include separate coarsening processes with different activation energies. The same model is used to describe the differences in pore spacing evolution between pre-coarsened and as-received systems.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: DOE/ER
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6388375
• Report Number(s): LBL-29643; ON: DE91004415
• Resource Relation: Other Information: Thesis (Ph.D.)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CERAMICS
SINTERING
ALUMINIUM OXIDES
CREEP
DILATOMETRY
MICROSTRUCTURE
PARTICLE SIZE
POWDER METALLURGY
STRAINS
TEMPERATURE EFFECTS
ZINC OXIDES
ALUMINIUM COMPOUNDS
CHALCOGENIDES
CRYSTAL STRUCTURE
FABRICATION
MECHANICAL PROPERTIES
METALLURGY
OXIDES
OXYGEN COMPOUNDS
SIZE
THERMAL ANALYSIS
ZINC COMPOUNDS
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