External pressure (uniaxial or isostatic) is usually necessary to form a th
in and defect-free joint in green state joining of Sic ceramics. A successf
ul method of joining Sic in the green state using a liquid polymer precurso
r, allylhydridopolycarbosilane (AHPCS), without applied pressure, is descri
bed. The thermal decomposition behavior of the polymer was examined, and de
fect formation during joint evolution was investigated by interrupting the
heat treatment at various stages. Cracks and pores were observed in the joi
nts formed by pure AHPCS during the pyrolysis of the polymer precursor. Add
ing Sic powder to the joining paste eliminated defect formation. Optimum Si
c loading in the paste was determined to be in the range of 25-35 vol%. Joi
nts formed by AHPCS + (SiC + 5 wt% B) paste were essentially indistinguisha
ble from the matrix and had an average strength of 323 MPa, comparable to t
hat of the control sample.