B

4

C induced SiC/SiC composites were prepared by prepreg-melt infiltration method. Oxidation behavior and self-healing mechanisms of B

4

C modified SiC matrix was studied at different oxidized temperatures. Self-healing behavior of the SiC–B

4

C matrix has also been noticed

cracks were filled by the oxidation products at the high temperatures. Moreover

the oxidation resistance of the SiC/SiC–B

4

C composites at elevated temperature was also investigated. The results

demonstrate that when the oxidation temperature is 700 ℃

B

2

O

3

glasses are formed on the surface of ceramic by B4C oxides. B

2

O

3

is observed as the major phase in SiC matrix. With the temperature increasing

SiO

2

phases are formed

and combined with B

2

O

3

phases to form the liquid borosilicate glass. When the temperature rises to 1200 ℃

the borosilicate glass will decomposes into SiO

2

and gaseous B

2

O

3

. At 1350 ℃

the content of B

2

O

3

decreases rapidly for borosilicate glass decomposing into B

2

O

3

which volatilizes itself. On the other hand

high temperature will cause the viscosity of borosilicate glass to decrease

hence

accelerates the oxygen diffusion. SiC/SiC–B

4

C composites retain great mechanical properties at 1200 ℃ for 50 h. The main mechanisms are that borosilicate glass oxidized from B

4

C can heal cracks in the composites effectively.