Showing papers by "Patrick S. Nicholson published in 2008"
TL;DR: In this article, a precursor for reaction-bonded mullite (RBM) is formulated by premixing Al 2 O 3, Si, mullite seeds and mixed-rare-earth-oxides (MREO).
Abstract: A precursor for reaction-bonded mullite (RBM) is formulated by premixing Al 2 O 3 , Si, mullite seeds and mixed-rare-earth-oxides (MREO). An ethanol suspension thereof is stabilized with polyethyleneimine protonated by acetic acid. The solid in the suspension is infiltrated into unidirectional mullite/alumina fiber-preforms by electrophoretic infiltration deposition to produce fiber-reinforced, RBM green bodies. Crack-free composites with ≤25% porosity were achieved after pressureless sintering at 1300 °C. Pre-coating the fibers with AlPO 4 as a weak intervening layer facilitates significant fiber pullout on composite fracture and confers superior damage tolerance. The bend strength is ∼170 MPa at 25 °C ≤ T ≤ 1100 °C. At 1200 °C, the composite fails in shear due to MREO-based, glassy phase formation. However, the AlPO 4 coating acts as a weak layer even after thermal aging at 1300 °C for 100 h.
54 citations
28 Mar 2008
26 citations
28 Mar 2008
7 citations
TL;DR: In this paper, an approach based on geometrical correction function of necking is proposed to model the bridging ligament response and compared with experimental single Ni-ligament test using digital image correlation (DIC) technique.
Abstract: The toughening of brittle materials with a ductile layer greatly enhances the composite fracture toughness. The behavior of a single constrained ligament is what characterize this enhancement. In this article, an approach based on geometrical correction function of necking is proposed to model the bridging ligament response and compared with experimental single Ni-ligament test using digital image correlation (DIC) technique.
4 citations