Mechanical Properties of Silicon Nitride Porous Ceramics with Bimodal Porosity

Abstract:

In this Paper, Silicon Nitride Porous Ceramics with Hierarchical Porosity Were Prepared Using Pressureless Sintering and their Mechanical Properties as a Function of Porosity and Pore Size Were Analyzed. In these Porous Ceramics, Macro-Pores with the Pore Size of 0.1 µm Were Formed by the Continuous Reaction of ZrP₂O₇ at ~250 °C and Macro-Cellular Pores with the Pore Size of 10~30μm Were Formed by the Burnout of Starch at ~550 °C or the Sublimation of Naphthalene at 80 °C. The Flexural Strength Decreased from 105 MPa to 6 MPa with the Porosity Increased from 35% to 65%. The Obtained Results Showed that the Flexural Strength Was Fit for the Equation of σ=σ₀exp(-bP), where σ₀ Is the Bending Strength of Nonporous Body of the same Material, P Is the Porosity and b Is the Factor Determines by Pore Structure. The Difference of Pore Size Was Determined by the Different Value of b and the Value of b Increased with the Increasing of Pore Size. Macro-Pores with the Pore Size of 0.1 µm Referred to a b Value of 4.3 and Macro-Cellular Pores with the Pore Size of 10 μm and 30 μm Referred to a b Value of 5.1 and 6.0 Respectively.

• Periodical: Key Engineering Materials (Volume 508)
• Pages: 69-75
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.508.69
• Online since: March 2012
• Authors: Fei Chen, Qiang Shen, Lian Meng Zhang
• Keywords: Bimodal Porosity, Mechanical Property, Si₃N₄ Porous Ceramics

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