炭/炭-陶瓷/炭多元复合材料的原位热压制备与性能

以纤维素和凹凸棒石(PG)为原料,在220℃下水热24h制备凹凸棒石/炭(PG/C)复合材料。采用浸渍-炭化工艺在炭/炭(C/C)复合材料中引入PG/C作为添加剂,一步热压对材料最终成型,原位获得C/C-陶瓷/C复合材料。研究了添加PG/C对C/C力学性能和抗氧化性能的影响。结果表明:PG/C在热压过程中转变为顽辉石/C,顽辉石/C通过"填充"和"桥联"起增强作用,顽辉石陶瓷表面负载纳米炭层有效避免了陶瓷相与基体炭间弱结合的产生。随着PG/C中表面负载纳米炭含量的减少,C/C的强度逐渐增加。当炭含量为13%的PG/C作为添加剂时,C/C的抗弯强度为263MPa,弹性模量为47GPa,相对于没有添加剂的C/C抗弯强度提高了45%,弹性模量提高了42%;相对于以PG作为添加剂的C/C抗弯强度提高了16%,弹性模量提高了27%。添加PG/C使C/C抗氧化性得到了提高;1 000℃下C/C的质量损失降低了12%~18%。

In-situ hot pressing preparation and properties of carbon/carbon-ceramic/carbon multiple composites

Palygorskite/carbon (PG/C)composites were synthesized via a hydrothermal route at 220 ℃ for 24 h using palygorskite and cellulose (PG)as raw materials.The obtained nano PG/C composites were introduced into the carbon/carbon (C/C)composites during the impregnation-carbonization process.Thus the C/C-ceramic/C com-posites were in-situ prepared by one-step hot pressing method.The mechanical and antioxidant properties were stud-ied for C/C composites using PG/C as additives.The results show that the PG/C converts to enstatite/C during hot pressing process.The resulted enstatite/C enhances the mechanical properties of C/C composites by filling and bridging,and the nano C layer loading on the surface of enstatite ceramic avoids weak-binding between ceramic phase and C matrix.Along with the decrease of nano C loading on surface of PG/C,the strength of C/C increases gradually.The PG/C with C content of 13% exhibits flexural strength of 263 MPa and elastic modulus of 47 GPa. Compared to that of C/C without additive,the values increases by 45% and 42% respectively.Compared to that of C/C introduced PG as additive,the value increases by 16% and 27% respectively.Also,the antioxidant properties of C/C improve due to the doped PG/C.The mass loss reduces by 12%-18% at 1 000 ℃.