Microstructure and growth mechanism of ZrO2 nanorod network via oxyacetylene torch ablation

doi:10.1016/j.matlet.2014.03.012

Materials Letters

Volume 123, 15 May 2014, Pages 217-220

https://doi.org/10.1016/j.matlet.2014.03.012 Get rights and content

Highlights

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The ZrO₂ network nanorods are synthesized without a metal catalyst via oxyacetylene torch ablation.
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A developed VLS and OAG model is discussed as the growth mechanism.
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ZrO₂ nanoparticles act as the growth catalyst and growth site of ZrO₂ nanorods.
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ZrO₂ nanorods have a significant increase in length in the border region.

Abstract

In this work, the network structure of ZrO₂ nanorods was firstly synthesized without a metal catalyst. A developed vapor–liquid–solid (VLS) and oxide-assisted growth (OAG) model is discussed as the growth mechanism of ZrO₂ nanorods. ZrO₂ nanoparticles, as a growth catalyst, provide zirconium and oxygen atoms for the formation of the nanorods and serve as a growth site as well. In the center and transition regions, ZrO₂ nanorods with a diameter of 30–54 nm finally grow into a network of ZrO₂ layer during the cooling process. In the border region, due to the appropriate growth temperature and adequate ZrO₂ vapors, ZrO₂ nanorods with a significant increase in length are synthesized during the ablation process.

Graphical abstract

Introduction

Great research interest has been devoted to one-dimensional (1D) nanostructural materials such as carbon nanotubes [1], nanowires [2] and nanorods [3] owing to their small dimensions and unique physical characteristics. ZrO₂ nanorods have attracted much attention in the fields of superplastic structural ceramics and transformation toughening, electrochemical devices, catalysis and sensors [4] due to their crystalline perfection, large surface area and small dimensions. However, only few studies on the synthesis of ZrO₂ nanorods have been reported, except for using annealing the precursor powders originating from the inverse microemulsion system [5] and eggshell membranes as templates while using inexpensive inorganic salts as precursors [6]. The vapor–liquid–solid (VLS) process is a fundamental mechanism for the growth of ZrO₂ nanorods similar to other kinds of 1D nanomaterials [7].

Recently, Li et al. [8] reported a useful method of synthesizing silica nanowires via ablation of SiC-containing coating using an oxyacetylene torch. The average diameter of the obtained nanowires was only 150 nm with a length of more than 100 µm. This method could be extended for manufacturing other 1D nanoscale oxide materials by ablation of the corresponding original carbide coatings. To expand the preparation methods of ZrO₂ nanorods, here, ZrO₂ nanorods are fabricated by ablation of a ZrC nanostructural coating [9] using an oxyacetylene torch. The growth model and mechanism of ZrO₂ nanorods are proposed and discussed.

Section snippets

Experimental

The ZrC nanostructure coating was prepared on carbon/carbon (C/C) composites (∅30 mm×10 mm, 1.72 g/cm³, 2D) by chemical vapor deposition (CVD). The experimental procedures were described in our previous papers [10]. The ablation test was carried out in a flowing oxyacetylene torch environment according to the GJB323A-96 Ablation Standard of China with 4200 kW/m² heat flux [10]. Table 1 shows the ablation parameters of the oxyacetylene torch.

Phase composition and morphology of the coatings before

Results and discussion

The XRD result (Fig. 1a) indicates that the ablation products are mainly composed of monoclinic ZrO₂. The ablation morphology of the cross-section in the center region (Fig. 1b) shows some micropores filled by molten ZrO₂ in the dense coating after ablation, which results from the release of CO and CO₂ produced by the oxidation of ZrC during ablation. Additionally, it should be noted that the ZrO₂ layer composed of network nanorods is found firstly on the ablated coating surface (labeled by the

Conclusions

ZrC network nanorods were synthesized without a metal catalyst via ablation of ZrC nanostructure coating using an oxyacetylene torch in this work. The developed VLS and OAG model is proposed to illustrate the growth mechanism of the nanorods. Owing to the formation of ZrO₂ nanoparticles, acting as the catalyst and growth site, the appropriate temperature and the supplement of ZrO₂ vapor in different regions, the ZrO₂ network nanorods can be synthesized with different lengths from the center to

Acknowledgments

This work has been supported by the National Natural Science Foundation of China under Grant nos. 51272213 and 51221001.

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Based on the amount of stabilizer doped, it can be divided into tetragonal zirconia polycrystalline (TZP), partially stabilized zirconia (PSZ), fully stabilized zirconia (FSZ), etc. To date, various state-of-the-art strategies including high-temperature and high-pressure method [12], hydrothermal treatment [13,14], vapor ablation [15], template method [16] and molten-salt processing [17,18] have been reported for the synthesis of m-ZrO2 whiskers. Comparatively, only one pioneering work regarding chemical vapor deposition has been documented to prepare rod-like t-ZrO2 [19].
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Increasing contact area of the particles enables the carbothermal reduction of metal oxide and carbon at lower temperature and shorter time as compared to conventional techniques of carbide synthesis [19–24]. As-synthesized ZrC is always in particle form together with a few one-dimensional nanostructures like whiskers [12,25], nanorods [26,27] and nanofibers [11,28,29]. Among the one-dimensional structures, ZrC whisker is one of the very important reinforcement in composite materials, which not only can improve the ablation resistance but also enhance mechanical properties of the materials by forming mechanical interlocking with the matrix [30].
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View full text

Microstructure and growth mechanism of ZrO2 nanorod network via oxyacetylene torch ablation

Highlights

Abstract

Graphical abstract

Introduction

Section snippets

Experimental

Results and discussion

Conclusions

Acknowledgments

Self-oriented regular arrays of carbon nanotubes and their emission properties

Science

Room-temperature ultraviolet nanowire nanolasers

Science

Synthesis and crystallization of anisotropic shaped ZrO2 nanocrystalline powders by hydrothermal process

Mater Lett

Synthesis of dispersed ZrO2 nano-laminae composed of ZrO2 nanocrystals

Mater Lett

Synthesis and characterization of zirconia nanorods

J Am Ceram Soc

Microstructure and growth mechanism of ZrO₂ nanorod network via oxyacetylene torch ablation

Synthesis and crystallization of anisotropic shaped ZrO₂ nanocrystalline powders by hydrothermal process

Synthesis of dispersed ZrO₂ nano-laminae composed of ZrO₂ nanocrystals