Zirconium Aluminum Carbides: New Precursors for Synthesizing ZrO2–Al2O3 Composites

He, Lingfeng; Bao, Yiwang; Zhou, Yanchun

doi:10.1111/j.1551-2916.2009.03281.x

Cited by 8 publications

(5 citation statements)

References 63 publications

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“…The oxidized grains of Hf-Al-C ceramics show a similar shape as those before oxidation and the t-HfO 2 and amorphous Al 2 O 3 are homogenously mixed at nanoscale, indicating that Hf and Al are oxidized simultaneously without an obvious diffusion. The nonselective oxidation of Hf-Al-C ceramics is similar to Zr-Al(Si)-C ceramics (Zr 2 Al 3 C 4 , Zr 2 [Al(Si)] 4 C 5 , Zr 3 [Al (Si)] 4 C 6 ), [16][17][18] which is most properly associated with their similar crystal structures. The crystal structures for all these carbides can be described as transition metal carbides in the NaCltype structure being interleaved by aluminum carbide units (for Zr-Al-Si-C compounds, about 11 mol% Al is replaced by Si).…”

Section: Discussionmentioning

confidence: 86%

Oxidation Behavior of Ternary Carbide Ceramics in Hf–Al–C System in Air

Nian

et al. 2010

Journal of the American Ceramic Society

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The oxidation behavior of Hf–Al–C ceramics containing 37.5 wt% Hf3Al3C5, 30.5 wt% Hf2Al4C5, and 32.0 wt% Hf3Al4C6 has been investigated at 900°–1300°C in air. The oxidation kinetics approximately follows a linear law with the activation energy of 194±12 kJ/mol. The oxidation resistance of Hf–Al–C ceramics at high temperature is superior to HfC. The oxide scale is porous and composed of well‐mixed t‐HfO2 and Al2O3 as well as residual free carbon. The stabilization mechanisms of t‐HfO2 and free carbon have been discussed. The simultaneous oxidation of Hf and Al in Hf–Al–C ceramics can be attributed to their close oxygen affinity as well as the strong coupling between Hf–C blocks and Al–C units in the crystal structures.

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Section: Discussionmentioning

confidence: 86%

Oxidation Behavior of Ternary Carbide Ceramics in Hf–Al–C System in Air

Nian

et al. 2010

Journal of the American Ceramic Society

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“…During service, high‐temperature exposure with extended periods often leads to inevitably sintering of the ceramic top coat . The detailed sintering behavior of TBCs has been intensively investigated . However, different regions of the top coat along through‐thickness direction are exposed to different temperatures under gradient thermal cyclic test.…”

Section: Resultsmentioning

confidence: 99%

“…26 The detailed sintering behavior of TBCs has been intensively investigated. 15,27 However, different regions of the top coat along through-thickness direction are exposed to different temperatures under gradient thermal cyclic test. The inner temperatures of YSZ coating decrease gradually from surface region to the interface between top coat and BC.…”

Section: Sintering Of the Top Coatmentioning

confidence: 99%

Sintering‐induced delamination of thermal barrier coatings by gradient thermal cyclic test

et al. 2017

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Lifetime is crucial to the application of advanced thermal barrier coatings (TBCs), and proper lifetime evaluation methods should be developed to predict the service lifetime of TBCs precisely and efficiently. In this study, plasma‐sprayed YSZ TBCs were subjected to gradient thermal cyclic tests under different surface temperatures, with the aim of elucidating the correlation between the coating surface temperature and the thermal cyclic lifetime. Results showed that the thermal cyclic lifetime of TBCs decreased with the increasing of surface temperatures. However, the failure modes of these TBCs subjected to thermal cyclic tests were irrespective of different surface/BC temperatures, that is, sintering‐induced delamination of the top coat. The thickness of thermally grown oxide (TGO) was significantly less than the critical TGO thickness to result in the failure of TBCs through the delamination of top coat. There was no phase transformation of the top coat after failure. In contrast, in the case concerning the top coat surface of the failure specimens, the elastic modulus and microhardness increased to a comparable level due to sintering despite of the various thermal cyclic conditions. Consequently, it is conclusive that the failure of TBCs subjected to gradient thermal cyclic test was primarily induced by sintering during high‐temperature exposure. A delamination model with multilayer splats was developed to assist in understanding the failure mechanism of TBCs through sintering‐induced delamination of the top coat. Based on the above‐described results, this study should aid in facilitating the lifetime evaluation of the TBCs, which are on active service at relatively lower temperatures, by an accelerated thermal cyclic test at higher temperatures in laboratory conditions.

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“…In general, micro‐structural features such as multiphases and porosity affect the Vickers hardness of ceramic materials . He et al have reported that the hardness of Al 2 O 3 ‐ZrO 2 composites is mainly influenced by the density of Al 2 O 3 , which may account for the decrease in Vickers hardness after ECD treatment, especially in NANOZR.…”

Section: Discussionmentioning

confidence: 99%

A novel method of surface modification by electrochemical deoxidation: Effect on surface characteristics and initial bioactivity of zirconia

Liu

Hong

et al. 2016

J Biomed Mater Res

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The aim of this study was to investigate and compare the surface characteristics and initial bioactivity of ceria-stabilized zirconia/alumina nanocomposite (NANOZR) with those of yttria-stabilized zirconia (3Y-TZP) and pure titanium (CpTi) following the use of three surface modification methods; polishing, sandblasting/acid-etching (SB-E) and electrochemical deoxidation (ECD). Physical properties including surface morphology, chemical composition, X-ray diffraction, surface wettability, surface roughness, and hardness were measured. Osteoblast-like MC3T3-E1 cells were used to examine cell morphology and attachment to the surfaces of the materials. ECD treated NANOZR (NANOZR-E) showed a well-arranged, self-organized microporous surface structure with significantly low contact angles when compared with the other specimens (p < 0.05). NANOZR-E also demonstrated a slight decrease in monoclinic phase content (-4.4 wt %). The morphology and attachment of MC3T3-E1 cells on NANOZR-E were similar to those on polished and SBE-treated CpTi surfaces. Higher cell affinity was observed on NANOZR-E when compared with ECD treated 3Y-TZP. The findings of this study indicate the effectiveness of the novel technique, ECD, in the formation of a microporous surface on NANOZR when compared with both CpTi and 3Y-TZP. Moreover, this method also appears to improve the biological activity of NANOZR during the initial stage. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2641-2652, 2017.

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Zirconium Aluminum Carbides: New Precursors for Synthesizing ZrO₂–Al₂O₃ Composites

Cited by 8 publications

References 63 publications

Oxidation Behavior of Ternary Carbide Ceramics in Hf–Al–C System in Air

Oxidation Behavior of Ternary Carbide Ceramics in Hf–Al–C System in Air

Sintering‐induced delamination of thermal barrier coatings by gradient thermal cyclic test

A novel method of surface modification by electrochemical deoxidation: Effect on surface characteristics and initial bioactivity of zirconia

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