Influence of carbon nanotubes and silicon carbide whiskers on the mechanical loss due to grain boundary sliding in 3-mol% yttria-stabilized tetragonal zirconia polycrystals

2006 ◽  
Vol 442 (1-2) ◽  
pp. 175-178 ◽  
Author(s):  
C. Ionascu ◽  
R. Schaller
Keyword(s):  
Carbon Nanotubes ◽  
Silicon Carbide ◽  
Grain Boundary ◽  
Tetragonal Zirconia ◽  
Grain Boundary Sliding ◽  
Mechanical Loss ◽  
Silicon Carbide Whiskers ◽  
Boundary Sliding

High Temperature Mechanical Loss Spectrum of 3Y-TZP Zirconia Reinforced with Carbon Nanotubes or Silicon Carbide Whiskers

2008 ◽  
Vol 137 ◽  
pp. 29-34 ◽  
Author(s):  
Claudia Ionascu ◽  
Robert Schaller
Keyword(s):  
Carbon Nanotubes ◽  
Silicon Carbide ◽  
High Temperature ◽  
Grain Boundary ◽  
Grain Boundary Sliding ◽  
Mechanical Spectroscopy ◽  
Multiwalled Carbon ◽  
Fine Grained ◽  
Silicon Carbide Whiskers ◽  
Boundary Sliding

High temperature plasticity of fine-grained ceramics (ZrO2, Al2O3, etc) is usually associated with a grain boundary sliding process. The aim of the present research is then to improve the high-temperature mechanical strength of polycrystalline zirconia (3Y-TZP) through the insertion of multiwalled carbon nanotubes (CNTs) or silicon carbide whiskers (SiCw), which are susceptible to pin the grain boundaries. The effect of these nano-sized particles on grain boundary sliding has been studied by mechanical spectroscopy.

scholarly journals Effects of Carbon Nanotubes on Grain Boundary Sliding in Zirconia Polycrystals

2005 ◽  
Vol 17 (1) ◽  
pp. 88-91 ◽  
Author(s):  
M. Daraktchiev ◽  
B. Van de Moortèle ◽  
R. Schaller ◽  
E. Couteau ◽  
L. Forró
Keyword(s):  
Carbon Nanotubes ◽  
Grain Boundary ◽  
Grain Boundary Sliding ◽  
Boundary Sliding

Grain Boundary Characterization in Yttria-Stabilized Zirconia by TEM Spectrum Lines

2000 ◽  
Vol 6 (S2) ◽  
pp. 220-221
Author(s):  
N. D. Evans ◽  
P. H. Imamura ◽  
M. L. Mecartneyf
Keyword(s):  
Grain Boundary ◽  
Tetragonal Zirconia ◽  
Light Element ◽  
Grain Boundary Sliding ◽  
Crystalline Materials ◽  
Fine Grained ◽  
User Facility ◽  
Near Net Shape ◽  
Net Shape Forming ◽  
Boundary Sliding

The superplasticity exhibited by some fine-grained ceramics, notably 3-mol% yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP), offers interesting possibilities to lower manufacturing costs by near net shape forming. Both glassy and crystalline materials have been added to pure 3 Y-TZP to limit grain growth and promote grain boundary sliding during sintering and isostatic pressing. EDS spectrum lines have been used to characterize the distribution and extent of additive phases, but were not able to map some light-element components of additives (e.g., O and B in borosilicate glass). Additionally, quantification of the Si Kα peak was compromised by overlap with the Y L and Z L peaks. To both improve light element sensitivity and investigate potential changes in oxygen bonding at the grain boundaries, undoped 3 Y-TZP and 3 Y-TZP powders processed with 1 wt% barium silicate have been examined with TEM spectrum lines. Additionally, some elemental mapping has been performed. TEM specimens were examined in a 300 kV LaB6 Philips CM30T equipped with a Gatan imaging filter (GIF) at the ORNL SHaRE User Facility.

High Temperature Mechanical Spectroscopy Study of 3 mol% Yttria Stabilized Tetragonal Zirconia Reinforced with Carbon Nanotubes

2012 ◽  
Vol 184 ◽  
pp. 265-270 ◽  
Author(s):  
Mehdi Mazaheri ◽  
Daniele Mari ◽  
Robert Schaller ◽  
Gilbert Fantozzi
Keyword(s):  
Carbon Nanotubes ◽  
High Temperature ◽  
High Temperatures ◽  
Tetragonal Zirconia ◽  
Grain Boundary Sliding ◽  
Mechanical Spectroscopy ◽  
Mechanical Loss ◽  
Multiwalled Carbon ◽  
Restoring Force ◽  
Low Frequencies

Composites containing 3 mol% yttria stabilized tetragonal zirconia (3Y-TZP) reinforced with multiwalled carbon nanotubes (CNTs) with various amounts of CNTs (3Y-TZP / X wt% CNT, X= 0, 0.5, 1.5, 3 and 5) were processed by spark plasma sintering. Microscopic analysis proves that CNTs were well dispersed and embedded in grain boundaries of the sintered body. High temperature mechanical properties have been investigated using mechanical spectroscopy and low stress (6 MPa) creep. The isothermal spectrum (measured at 1600 K) consists of a mechanical loss peak at a frequency of about 0.1 Hz, which is superimposed on an exponential increase at low frequency. The absence of a well-marked peak in monolithic 3Y-TZP is justified considering that restoring force decreases at low frequencies or high temperatures due to the elasticity of neighboring grains. Therefore, strain is no more restricted and the mechanical loss increases exponentially, which is correlated to macroscopic creep. However, with CNT additions the mechanical loss decreases and a better resolved peak was observed. In parallel, the results have shown that the creep rate drastically decreases with CNT additions. These results can be interpreted by the pinning effect of CNTs which can hinder grain boundary sliding at high temperatures, resulting in a creep resistance improvement.

Examination of Fracture Interfaces in Silicon Nitride

1975 ◽  
Vol 33 ◽  
pp. 60-61
Author(s):  
Nancy J. Tighe
Keyword(s):  
Silicon Nitride ◽  
Grain Boundary ◽  
Crack Growth ◽  
Subcritical Crack Growth ◽  
Slow Crack Growth ◽  
Ceramic Materials ◽  
Grain Boundary Sliding ◽  
Boundary Phase ◽  
Turbine Engines ◽  
Boundary Sliding

Silicon nitride is one of the ceramic materials being considered for the components in gas turbine engines which will be exposed to temperatures of 1000 to 1400°C. Test specimens from hot-pressed billets exhibit flexural strengths of approximately 50 MN/m2 at 1000°C. However, the strength degrades rapidly to less than 20 MN/m2 at 1400°C. The strength degradition is attributed to subcritical crack growth phenomena evidenced by a stress rate dependence of the flexural strength and the stress intensity factor. This phenomena is termed slow crack growth and is associated with the onset of plastic deformation at the crack tip. Lange attributed the subcritical crack growth tb a glassy silicate grain boundary phase which decreased in viscosity with increased temperature and permitted a form of grain boundary sliding to occur.

INTERNAL FRICTION PEAKS CONNECTED WITH GRAIN BOUNDARY SLIDING IN Al

1983 ◽  
Vol 44 (C9) ◽  
pp. C9-759-C9-764
Author(s):  
E. Bonetti ◽  
A. Cavallini ◽  
E. Evangelista ◽  
P. Gondi
Keyword(s):  
Internal Friction ◽  
Grain Boundary ◽  
Grain Boundary Sliding ◽  
Boundary Sliding
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