Preparation of Continuous Alumina Fiber with Nano Grains by the Addition of Iron Sol.

Luqun Liu,Yunzhu Ma,Shuwei Yao,Juan Wang,Wensheng Liu

doi:10.3390/ma13235442

Abstract

Continuous alumina fiber exhibits excellent mechanical properties owing to its dense microstructure with fine grains. In this study, alumina fiber was prepared by the sol–gel method using iron sol as a nucleating agent. It was proposed that the α-Al2O3 grain size be adjusted based on the modification of colloidal particle size. The effect of holding temperature and reaction material ratio on the iron colloidal particle size was studied. The microstructure of alumina fiber was characterized by scanning electron microscopy (SEM). The experiment results indicated that iron colloidal particle size increases with the holding temperature and the NH4HCO3/Fe(NO3)3·9H2O ratio. The alumina fiber with uniform nano α-Al2O3 grains was obtained by calcination at 1400 °C for 5 min. The mean grain size tends to rise with the mean colloidal particle size. Using the iron sol as a nucleating agent, the fiber with a mean grain size of 22.5 nm could be formed. The tensile strength of fibers increased with the decrease of grain size.

Highlights

Continuous alumina fiber has been widely applied in various fields such as aerospace, military industry and automobile, owing to its high strength, high modulus and exceptional oxidation resistance [1,2,3,4,5,6]
The morphology of iron colloidal particles obtained at different holding temperature is shown in
The sol that was prepared at temperatures ranging from 25 to 70 ◦ C, its colloidal particle size mainly distributed in the range of

Summary

Introduction

Continuous alumina fiber has been widely applied in various fields such as aerospace, military industry and automobile, owing to its high strength, high modulus and exceptional oxidation resistance [1,2,3,4,5,6]. NextelTM 610 fiber and FP fiber are typical alumina fibers with high purity of α-Al2 O3 (>99 wt.%). The NextelTM 610 fiber, having a grain size of ~100 nm, exhibits high tensile strength of greater than 3.1 GPa [3], while the tensile strength of FP fiber is only about. 1.4 GPa due to its larger grains (>500 nm) [5]. Hay et al [6] found that the tensile strength of NextelTM. Controlling the grain size is essentially important in order to prepare high performance alumina fiber

Methods

Results

Conclusion