摘要
以碳化硅粉末、纳米碳黑、短碳纤维为原料,采用模压成型、反应烧结法制备了力学性能优异的碳化硅复合陶瓷。对短碳纤维增强反应烧结碳化硅复合陶瓷的机理进行了研究。结果表明:纳米碳黑由于其更高的反应活性,有效的抑制了短碳纤维与硅的反应,碳纤维仅外层与硅反应生成β-Si C,少量硅通过扩散进入碳纤维内层,短碳纤维得到有效保护。纳米碳黑完全反应的同时,碳纤维作为部分碳源填充了更多坯体气孔,更多气孔被Si之外的相填充使得复合陶瓷烧结体的残硅体积分数由20%降至12%,且有效的抑制了硅岛的形成。材料断口形貌中可观察到纤维拔出、纤维脱粘、和大量细小β-Si C晶粒拔出。相比于传统的反应烧结碳化硅陶瓷,添加碳纤维的碳化硅复合陶瓷的断裂韧性由4.06 MPa·m^(1/2)提升至5.11 MPa·m^(1/2);烧结体体积密度由3.04 g/cm^3降低至2.98 g/cm^3,弯曲强度由295 MPa提升至379MPa,碳化硅复合陶瓷的比强度提升了31%。
The short carbon fiber reinforced reaction bonded silicon carbide composite ceramic was fabricated by molding and reactive sintering, whose raw materials were silicon carbide powders, short carbon fiber and nano carbon black. The toughing mechanism of the silicon carbide composite ceramic was studied. The result shows that the reaction of carbon fiber with silicon is restrained greatly by nano carbon black due to its higher reactivity. Only the surface of carbon fiber reacts with silicon to form a Si C layer, and a small amount of silicon diffuse into the interior of carbon fiber. The volume of residual silicon of the composite decreases to 12% because the surface of carbon fiber acts as carbon material. We can see the fiber pullout, fiber debonding and intergranular fracture of fine β-Si C particles from the fracture surface morphology. Compared to the monolithic reaction bonded silicon carbide composite ceramic, the flexural strength increases from 295 MPa to 379 MPa, and the fracture toughness increases from 4.06 MPa·m^(1/2) to 5.11 MPa·m^(1/2); however, the bulk density decreases from 3.04 g/cm^3 to 2.98 g/cm^3, so an increase by 31% of specific strength are obtained.
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2015年第S1期183-186,共4页
Rare Metal Materials and Engineering
基金
国家自然科学基金(51372194)
教育部博士学科点专项科研基金(2012020111003)
关键词
碳化硅复合陶瓷
模压成型
短碳纤维
强韧化机理
silicon carbide composite ceramic
compression molding
short carbon fiber
toughening mechanism
