Effect of chemical vapor deposition of Si_3N_4, BN and B_4C coatings on the mechanical and dielectric properties of porous Si_3N_4 ceramic

摘要

The mechanical properties of porous Si_3N_4 ceramic are noticeably improved after chemical vapor deposition (CVD) of Si_3N_4, BN and B_4C coatings. The dielectric constant and loss of porous Si_3N_4 ceramic remain almost unchanged after CVD of BN, increase slightly after CVD of Si_3N_4, but increase greatly after CVD of B_4C. Overall, CVD of Si_3N_4 performs better than CVD of BN and B_4C in improving the mechanical properties and keeping the low dielectric constant and loss of porous Si_3N_4 ceramic.