Effect of high‐pressure vapor pretreatment on the microstructure evolution and tensile strength of zirconia fibers

Abstract

High-strength zirconia (ZrO 2 ) continuous fibers, which are potential candidates as ultra-high temperature thermal insulators and reinforced materials, are typically fabricated by dry spinning an organozirconium precursor. However, the uncontrolled decomposition of organozirconium precursor usually occurs upon heat treatment that breaks the continuous fibers into pieces, resulting in the loss of tensile strength.Herein, in this contribution, we aimed to maintain the integrity of ZrO 2 precursor fibers during heat treatment. For this purpose, novel high-pressure vapor (HPV) pretreatment of ZrO 2 precursor fiber was introduced. The HPV pretreatment is considered to be efficient for the removal of the organics in precursor, promoting the formation of amorphous structures of Zr(OH) 4 and Zr(OH) 3 HCO 3 . Combining the studies of microstructures and tensile strengths, it was found that the amorphous structures played roles of cross-linking points, keeping the fibers integrity during the followed heat treatment. After HPV pretreatment, the high-strength ZrO 2 continuous fibers would be obtained by direct sintering in air without any atmosphere which substantially lowered the cost. The tensile strengths of sintered ZrO 2 continuous fibers pretreated by an optimized HPV procedure could reach up to as high as 1.299 GPa. The HPV pretreatment method provides a high-efficiency, low-cost technique for preparing high-quality ceramic fibers. K E Y W O R D Shigh-pressure vapor pretreatment, polyaceticzirconium, tensile strength, transition process

Development of lutetium oxide continuous fibers with excellent mechanical properties

“…In addition, the intensity of the XRD diffraction peaks of the samples was strong with the increase in the pretreatment temperature, which was because higher pretreatment temperature would cause more Lu 2 O 3 nanocrystals in the pretreated fibers. That could act as crystal nuclei in the subsequent heat treatment process, induce the crystallization of Lu 2 O 3 , and promote the growth of Lu 2 O 3 grains in the fibers [43]. Ultimately, this led to larger Lu 2 O 3 grain sizes and higher crystallinities in the fibers with high pretreatment temperatures (Fig.…”

Recent advances in ZrO2 nanofibers: From structural design to emerging applications

“…After the temperature of the melt decreased or the solvent evaporated, the jet gradually solidified to form NFs, which were collected on the collector. The synthesis of ZrO 2 NFs through centrifugal spinning commonly involves the following three stages: (i) preparation of the precursor solution or melt with a high-molecular-weight zirconium-based polymer [63,64]; (ii) preparation of precursor NFs by a centrifugal spinning machine (Fig. 3b) [65,66]; (iii) removal of organic components by high-temperature sintering (Fig.…”

Aluminum nitride‐based ceramics with excellent thermal shock resistances

“…6,7 Second phases can be introduced in the form of particles, 2,8,9 whiskers, 10,11 fibers, 12,13 etc. The most successful method to mitigate thermal shock damage to ceramics has been to incorporate continuous fibers into the ceramic matrix, [14][15][16] but the process of making ceramic matrix composites is too complex and the cost is very high, continuous fibers also reduce the hardness of ceramics. 17,18 The thermal shock resistance of ceramics could be enhanced by the introduction or generation of nanoparticles in the ceramic matrix, 19 and the resulting composite fracture mode could be changed from brittle catastrophic failure to non-brittle one.…”