Effect of infiltrated eutectic AlSi on the microstructure and properties of C/C composites

Abstract

Eutectic AlSi alloy was pressure infiltrated into a porous C/C skeleton to develop a low cost new C/C composite for application without extreme high temperature. C/C composite possessed a density of 1.7 g/cm3 was prepared for comparison. The effects of filling AlSi with and without Al-Ti-C grain refiner on the microstructure and properties of C/C composites were mainly studied. Result indicated that the introduced AlSi interpenetrated with C/C skeleton and made the composites compact. In comparison with C/C composite, the compressive strength and particle erosion resistance were greatly enhanced while the density and thermal expansion coefficient (CTE) increased slightly. After adding the refiner, Si network involved dendritic Al in C/C-AlSi was transformed to refined mixed AlSi, Al bulk and Si surrounded dendritic Al, and two kinds of micro-cracks came into being, which resulted in the decreased strength, improved erosion property and increased CTE of C/C-AlSiR. Both AlSi textures and micro-cracks in the modified C/C composites determined the crack propagation and led to their different compressive behaviors and anti-erosion abilities.

Understanding the Role of a Cr Transition Layer in the Hot-Salt Corrosion Behavior of an AlSi Alloy Coating

“…Furthermore, the Si doping accelerated the selective oxidation of Al to generate an Al 2 O 3 protective layer. Unfortunately, during high-temperature corrosion exposure, the AlSi coatings suffered from significant elemental inter-diffusion [24][25][26][27][28][29][30]. According to the literature, the upward diffusion of Fe caused the creation of the (Fe 2 Al 5 + FeAl) alloy phase, which resulted in significant volume shrinkage and coating cracking.…”

Effect of preset interfacial ZrB2 particles on the microstructure and properties of C/C-AlSi composites

“…All the works indicated that the composites are promising materials for industrialization. In our recent study of C/C-AlSi, 22 the composites were prepared through pressure infiltration of eutectic AlSi into a fiber fabric based porous C/C skeleton in air, and the effect of grain refinement on the microstructure and property was discussed. To achieve a better and deeper infiltration, the C/C skeleton should be preheated to above 400 C which would result in oxidation of carbon and fast decreased strength of the C/C preform.…”