Effects of Carbon Nanotubes on Grain Boundary Sliding in Zirconia Polycrystals

Daraktchiev, M.; Moortèle, Bertrand Van de; Schaller, R.; Couteau, E.; Forró, Lászlø

doi:10.1002/adma.200400598

Cited by 22 publications

(14 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For CNTZrO 2 composites, it is reported that the reduction in the grain-boundary sliding caused by the addition of CNTs improves the creep resistance at high temperatures. 14) The high-temperature deformation of Si 3 N 4 ceramics mainly results from the grain-boundary sliding, due to the grain-boundary glassy phase. Although the high-temperature deformation behavior of the sample used in this study has not been studied yet, the swelling of the sample due to gas formation was probably restrained because the CNT dispersion improved the creep resistance.…”

Section: Resultsmentioning

confidence: 99%

Effect of CNT quantity and sintering temperature on electrical and mechanical properties of CNT-dispersed Si3N4 ceramics

Yoshio

Tatami

Wakihara

et al. 2011

J. Ceram. Soc. Japan

View full text Add to dashboard Cite

Electrically conductive carbon nanotube (CNT)-dispersed ceramics with high strength were fabricated by varying the CNT quantity and the firing temperature. We investigated the effect of these factors on density, electrical conductivity, bending strength, and microstructure of the developed ceramics. The relative density of the CNT dispersed Si 3 N 4 ceramics was higher than 90% except for the sample containing less than 1 wt % of CNTs and fired at a temperature of 1800°C. It was confirmed that CNTs exist in the samples with a higher density. The pullout length of CNTs on the fracture surface in samples fired at higher temperatures was shorter because of the degradation of the CNTs. By TEM observation, CNTs were found to exist in the grain boundary in the Si 3 N 4 ceramics, and their diameter was found to be almost the same as that of raw CNTs. Electrical conductivity appeared in the samples by adding CNTs more than 1 wt % though the sample by adding 0.5 wt % CNTs was insulator. The electrical conductivities of the samples increased with an increase in the firing temperature, which was explained by the grain growth of ¢-Si 3 N 4 . The bending strength of the samples with 1 wt % of CNTs was as high as that of samples without CNTs. Thus, CNT-dispersed Si 3 N 4 ceramics having both electrical conductivity and a higher bending strength were obtained by controlling the CNT quantity and the firing temperature.

show abstract

Section: Resultsmentioning

confidence: 99%

Effect of CNT quantity and sintering temperature on electrical and mechanical properties of CNT-dispersed Si3N4 ceramics

Yoshio

Tatami

Wakihara

et al. 2011

J. Ceram. Soc. Japan

View full text Add to dashboard Cite

show abstract

“…Regarding the high‐temperature mechanical properties of ceramic/CNTs composites, most studies reported in literature are related to mechanical spectroscopy measurements. Thus, a decrease in the high‐temperature background in 3YTZP/MWCNTs composites and an increase in the shear modulus with respect to monolithic 3YTZP has been reported by different authors . Daracktchiev et al .…”

Section: Introductionmentioning

confidence: 82%

“…Thus, a decrease in the high‐temperature background in 3YTZP/MWCNTs composites and an increase in the shear modulus with respect to monolithic 3YTZP has been reported by different authors . Daracktchiev et al . performed mechanical loss measurements in monolithic 3YTZP, SiO 2 ‐doped 3YTZP and 3YTZP with 5 wt% of MWCNTs, obtaining for the latter a significant decrease in the internal friction due to CNTs inclusions.…”

Section: Introductionmentioning

confidence: 88%

Influence of the Processing Route on the Carbon Nanotubes Dispersion and Creep Resistance of 3YTZP/SWCNTs Nanocomposites

et al. 2014

View full text Add to dashboard Cite

3YTZP matrix composites containing 2.5 vol% of single‐walled carbon nanotubes (SWCNT) were fabricated by Spark Plasma Sintering (SPS) at 1250°C, following different processing routines with the aim of optimizing the SWCNTs dispersion throughout the ceramic matrix. Microstructural characterization of the as‐fabricated samples has been performed by means of scanning electron microscopy (SEM). The specimens have been crept at 1200°C to correlate creep resistance and SWCNTs distribution. There are no creep experimental results on these nanocomposites reported in literature. Mechanical results show that the incorporation of SWCNTs into a 3YTZP matrix produces an increase in the strain rate at high temperature with respect to monolithic zirconia. The creep resistance of these nanocomposites decreases with the improvement of the SWCNTs dispersion, where a smaller SWCNTs agglomerate size and consequently a higher concentration of carbon nanotubes surrounding the 3YTZP grain boundaries is found. This fact indicates that SWCNTs act as a lubricant making grain‐boundary sliding easier during deformation of these composites.

show abstract

“…Samples were prepared as described previously [23]. Using single threads instead of bundles of fibers for dynamic mechanical thermal analysis prevents uncertainty in interpretation resulting from lack of uniformity of strain and from threads slipping past each other.…”

Section: Methodsmentioning

confidence: 99%

Toughness of Spider Silk at High and Low Temperatures

Yang¹,

Chen²,

Shao³

et al. 2005

Advanced Materials

113

View full text Add to dashboard Cite

The outstanding strength and toughness of certain spider and lepidopteran silks [1] has aroused considerable interest in recent years, [2] with research focusing primarily on the relationship between molecular structure and mechanical properties. [3] Environmental conditions such as ambient humidity, [4] acidity, [5] and UV radiation [6] all affect the mechanical properties of native silks to some degree. [7] Pronounced differences in mechanical properties were also observed when conditions such as the speed or temperature at spinning were varied [8] or when the silk was (or had been) submerged in solvents such as water, urea solution, or a range of alcohols, where it contracts in varying degrees. [9] Clearly, silk is affected by the ambient conditions both during spinning and during testing. Thus the mechanical properties of silks produced and tested under very specific conditions can be used as ªwindowsº to look into the interaction of production conditions and silk mechanics (studied by varying the extrusion conditions [8] ) as well as the details of the silk fine structure (examined by varying the testing conditions [9] ). Both are not without some importance to the spiders as they can affect the performance of the web. Spiders are ectotherms, and ambient temperature has a strong effect on spider behavior and life history, [10] in addition to affecting the material spun under those conditions. Climate further affects the material properties of silk and the engineering of the whole web, [2a,11] because webs are typically spun in the early morning, when humidity is high while temperature is low. Hence we may assume that evolution has led to a set of design criteria for silk that allow the material to function well over a range of temperatures (from ca. 0 C to 30 C), humidities (from ca. 20 to 100 RH (relative humidity)), and spinning speeds (from ca. 1 mm s ±1 to ca. 1000 mm s ±1 ). However, what about the properties outside that range? Moreover, as mentioned above, the inter-relation of environmental conditions and silk behavior can provide insights into the structure±func-tion relationship. Hence we posed, firstly, the question of whether a major spider silk, i.e., a silk that is normally used for lifelines and important supporting web-components, can perform outside the range of temperatures under which it evolved. Secondly, we were interested in the light that mechanical performance would shed on the structure of the material if we tested our silks under as wide a temperature regime as possible (i.e., ±60 to +150 C). Clearly, this would not only provide data of purely scientific value but also data of considerable commercial interest, as spider silk is often billed as a material with a great future. To study these questions (i.e., to examine the mechanical properties of a major spider silk over a wide temperature range), a dynamic mechanical thermal analyzer (DMTA) was used to measure both static and dynamic mechanical properties of single spider-silk threads. We measured the strain response of si...

show abstract

Effects of Carbon Nanotubes on Grain Boundary Sliding in Zirconia Polycrystals

Cited by 22 publications

References 24 publications

Effect of CNT quantity and sintering temperature on electrical and mechanical properties of CNT-dispersed Si3N4 ceramics

Effect of CNT quantity and sintering temperature on electrical and mechanical properties of CNT-dispersed Si3N4 ceramics

Influence of the Processing Route on the Carbon Nanotubes Dispersion and Creep Resistance of 3YTZP/SWCNTs Nanocomposites

Toughness of Spider Silk at High and Low Temperatures

Contact Info

Product

Resources

About