Compressive and Thermal Characterization of Syntactic Foams Containing Hollow Silicon Carbide Particles with Porous Shell

摘要

Silicon carbide hollow particle (SiC_(HS)) reinforced vinyl ester matrix syntactic foams are prepared and characterized for compressive properties and coefficient of thermal expansion (CTE). Two types of SiC_(HS) were utilized in 60 vol % to prepare syntactic foams. These SiC_(HS) had ratio of inner to outer radius of 0.91 and 0.84 for the thin and thick walled particles. The specific compressive strength values were 33.4 and 38.8 kPa/kg/m~3 and the specific compressive modulus values were 0.8 MPa/kg/m~3 and 0.6 MPa/kg/ m~3 for the thin and thick walled SiCHS-filled syntactic foams, respectively. The shell of the hollow particles contained microporous voids, and the porosity was estimated as 16.6% and 24.8% in the walls of the thin and thick walled particles, respectively. The shell porosity adversely affected the specific compressive strength and the modulus of the syntactic foam. However, the SiC_(HS)-filled syntactic foams exhibited low CTE values (26.7 and 15.9 × 10~(-6)/℃). These CTE values were 65.1% and 79.3% lower than the CTE of the neat resin. Such properties can be useful for applications where syntactic foams are exposed to high temperatures and dimensional stability is important. A theoretical model is used to estimate the porosity level in the SiC shells and estimate the effective mechanical properties of the porous SiC material that forms the particle shell. Such analysis can help in using the models as predictive tools to estimate the mechanical properties of syntactic foams.