The Role of Infiltration Temperature in the Reaction Bonding of Boron Carbide by Silicon Infiltration

Abstract

The present paper is concerned on the effect of infiltration temperature on the components, microstructure, and mechanical properties of reaction-bonded boron carbide (RBBC) ceramics. RBBC ceramics were fabricated by reactive infiltration of molten silicon (Si) into porous preforms containing boron carbide (B 4 C) and free carbon. It has been found that infiltration temperatures have significant influence on the infiltration reactions involved and therefore the evolution of different phases formed in the RBBC ceramics. An increase in grain size of boron carbide particles through the coalescence of neighboring grains was observed at certain infiltration temperatures. The morphology of silicon carbide (SiC) phases developed from discontinuous and cloud-like SiC to continuous and integrated SiC zones with the increase of infiltration temperatures. With increasing temperatures up to 1600°C, the hardness, flexural strength, and fracture toughness all increased. When the temperatures exceeded 1600°C, while the hardness and flexural strength decreased, the fracture toughness continued to increase.

Infiltration of Molten Silicon in a Porous Body of B 4 C Under Microwave Heating

“…In the present study we couldn't notice on any influence of the tretmant temperature on the hardness values. This finding is opposite to the results obtained in conventional method [18] where the influence of the infiltration temperature on the hardness values is strong. We used this data to modeling with Nemrodw software.…”

Gel‐casting process‐derived 3D‐interconnected porous carbon/B4C preform for reaction‐bonded boron carbide composites

“…It might cause the formation of “Necks” between neighboring boron carbide particles. As a result, the neighboring boron carbide particles further grew together and led to some coarsened boron carbide particles in the infiltrated sample . In contrast, the I‐GC composite shows much more uniform microstructures (Figure D‐F).…”

Reaction‐bonded B4C/SiC composites synthesized by microwave heating

“…The silicon used for the infiltration was in the form of lumps furnished by Alfa Aesar with the purity of 98.4% (0.45% of Fe, 0.08% of Al and 0.008% of Ca). According to the literature, conventional RBBC is usually fabricated under high vacuum (1.3 × 10 −2 ‐1.3 × 10 −3 Pa). This low pressure is incompatible with microwave heating because it promotes plasma formation into the microwave cavity.…”