Study On The Preparation And Properties Of Zirconium Carbied Nano Ceramic Fibers

Zirconium carbide(ZrC)ceramic has wide application in ultra-high temperature environment of more than 2000 ? due to its unique combination of high melting point,high hardness,good impact resistance and good conductivity.Many studies concerned the preparation and improvement of ZrC powders and composite materials,while rarely on ceramic fibers and thermal stability evaluation.It will contribute the study of fiber-reinforced composites in ultra-high-temperature environment if we conduct the researching of ZrC ceramic fibers.This paper aims to explore the preparation and properties of ZrC nano ceramic fibers by combined with sol-gel method and electrostatic spinning method.Based on the liquid precursor method for preparing ZrC ceramic,ZrC precursor sol was obtained after the mixture and concentration of inorganic substances and spinning additive Polyvinyl Pyrrolidone(PVP),and then ZrC nano ceramic fibers were prepared by sintering the precursor fibers which was produced by the electrospinning technique.The sample could be studied by a series of testing methods,such as TG-DSC,XRD,SEM,TEM,oxygen and nitrogen analyzer,material testing machine,etc.High temperature heat treatment method was used to study the thermal stability.The results were as follows.(1)Using the precursor solutions with 10 wt%PVP concentration,continuous uniform precursor fibers were fabricated by electrospinning method.The diameter of the fibers was about 400?430 nm.(2)ZrC nano ceramic fibers with good morphology could be obtained after calcination at 1300 ? for 2 h.The diameter of the ceramic fibers were about 285 nm.After sintering at 1500 ?for 2 h,the ceramic fibers had the lowest oxygen content of 9.0%,the minimum resistivity of 0.22 ?·cm and the maximum fracture strength of 0.198 MPa.(3)Thermal stability evaluation was investigated.The results showed that PVP could inhibit the growth of grain.When the concentration of PVP was 12 wt%,the ZrC nano ceramic fibers had good thermal stability,which could keep good morphology at 2500 ?.(4)The well-aligned precursor fibers were obtained through the rotating-drum method.When the spinning parameters were 22 kV,8 cm and 2500 r/min,the degree of orientation of the precursor fibers was best.After sintering at 1500 ? for 2 h,the electrical conductivity and mechanical properties of the directional ZrC nano ceramic fiber membranes were improved obviously.The resistivity was 0.14 ?·cm and the fracture strength was 3.450 MPa.