Enhanced thermoelectric and mechanical properties of p-type skutterudites with in situ formed Fe3Si nanoprecipitate

2017 ◽  
Vol 4 (10) ◽  
pp. 1697-1703 ◽  
Author(s):  
Shengyuan Peng ◽  
Jianhui Sun ◽  
Bo Cui ◽  
Xianfu Meng ◽  
Dandan Qin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Thermoelectric Properties ◽  
Indentation Fracture ◽  
Indentation Fracture Toughness ◽  
P Type

Hardness and indentation fracture toughness of La0.8Ti0.1Ga0.1Fe3CoSb12can be improved byin situformed Fe3Si, without sacrificing thermoelectric properties.

Synthesis and Properties of In-Situ MoSi2/SiC Composites

1993 ◽  
Vol 322 ◽  
Author(s):  
S. Jayashankar ◽  
S.E. Riddle ◽  
M. J. Kaufman
Keyword(s):  
Fracture Toughness ◽  
Mechanical Alloying ◽  
Room Temperature ◽  
Indentation Fracture ◽  
Processing Scheme ◽  
Indentation Fracture Toughness ◽  
Novel Processing ◽  
Sic Composites

AbstractCompositionally-tailored, silica-free, MoSi2/SiC composites with SiC content ranging from 0 to 40 percent were synthesized through a novel processing scheme involving mechanical alloying and in-situ reactions for the formation of the reinforcement. Room temperature indentation fracture toughness and hardness measurements were obtained from these silica-free composites and were compared with values obtained from silica-containing, conventionally-processed MoSi2/SiC composites.

Mechanical Characterization of Dense Hydroxyapatite Blocks

2006 ◽  
Vol 514-516 ◽  
pp. 1083-1086
Author(s):  
Cláudia M.S. Ranito ◽  
Fernando A. Costa Oliveira ◽  
João P. Borges
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Physical And Mechanical Properties ◽  
Full Density ◽  
Indentation Fracture ◽  
Mechanical Characterisation ◽  
Indentation Fracture Toughness ◽  
Ft Ir

Bioactive dense HAp ceramics possess a unique set of properties, which make them suitable as bone substitute. However, both physical and mechanical properties of HAp have to be evaluated in order to produce new materials that match the bone stiffness. This paper highlights the influence of both porosity and grain size on the four-point flexural strength and the indentation fracture toughness of pure dense HAp blocks sintered at 1300°C. Both discs and rectangular bars were produced by uniaxial pressing at 40MPa and sintered in static air at temperatures between 1150 and 1325°C for 1 h in order to assess the densification behaviour of the P120S medical grade HAp powder used. After sintering, both the density and the open porosity were measured. In addition to FT-IR, XRD and SEM, the mechanical properties of the dense HAp blocks, including Young´s modulus, flexural strength, Vicker´s hardness and fracture toughness, were characterized and whenever possible these properties were compared to those reported for cortical bone. Pressureless sintering to full density at temperatures below 1300°C does not occur for the stoichiometric powder used. The results obtained underline the importance of full mechanical characterisation of dense HAp so that new implant materials can be developed. There is a need to improve the microstructure and thus enhance mechanical strength of HAp ceramics, as it was found that flexural strength is closely related to the micropores present in the sintered samples.

Microstructure and Mechanical Properties of Sm1-xSrxCo0.2Fe0.8O3

2000 ◽  
Vol 15 (7) ◽  
pp. 1505-1513 ◽  
Author(s):  
Y-S. Chou ◽  
J. W. Stevenson ◽  
T. R. Armstrong ◽  
J. S. Hardy ◽  
K. Hasinska ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Fracture Behavior ◽  
Room Temperature ◽  
Indentation Fracture ◽  
Flexure Strength ◽  
Indentation Toughness ◽  
Indentation Fracture Toughness ◽  
Microhardness Indentation ◽  
Biaxial Flexure

The room temperature mechanical properties of a mixed conducting perovskite Sm1?xSrxCo0.2Fe0.8O3 (x = 0.2 to 0.8) were examined. Density, crystal phase, and microstructure were characterized. It was found that the grain size increased abruptly with increasing Sr content. Mechanical properties of elastic modulus, microhardness, indentation fracture toughness, and biaxial flexure strength were measured. Young's modulus of 180–193 GPa and shear modulus of 70–75 GPa were determined. The biaxial flexure strength was found to decrease with increasing Sr content from ∼70 to ∼20 MPa. The drop in strength was due to the occurrence of extensive cracking. Indentation toughness showed a similar trend to the strength in that it decreased with increasing Sr content from ∼1.1 to ∼0.7 MPa m1/2. In addition, fractography was used to characterize the fracture behavior in these materials.

Comparison of R-Curve Behavior of Si3N4 Measured by Indentation Method and Single-Edge V-Notched Beam Technique (SEVNB)

2009 ◽  
Vol 409 ◽  
pp. 308-312
Author(s):  
Jana Špaková ◽  
Ján Dusza
Keyword(s):  
Fracture Toughness ◽  
Crack Opening ◽  
Single Edge ◽  
Indentation Fracture ◽  
Indentation Method ◽  
Indentation Toughness ◽  
Indentation Fracture Toughness ◽  
Beam Technique

Study compare R-curve behaviour of silicon nitride obtained using Vickers indented beam specimens and single edge V-notched beam (SEVNB). R-curve measurement realized by Vickers indented beam was reported by Krause. Crack growth using single edge V-notched beam was observed in situ. The indentation experiments, in comparison with SEVNB method revealed higher R-curve values (KR=3.3 – 4.8 MPa.m1/2). The discrepancy in the R-curve results is attributed to inaccuracy related to the determination of indentation toughness. The indentation fracture toughness may include the aspects of crack opening behaviour, residual indentation stress intensity.

scholarly journals Analyzing Time on Sample During Nanoindentation

2016 ◽  
Vol 13 (2) ◽  
pp. 74-79 ◽  
Author(s):  
A. S. Bhattacharyya ◽  
P Kumar ◽  
N Rajak ◽  
R.P Kumar ◽  
A Sharma ◽  
...  
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Significant Contribution ◽  
Substrate Effect ◽  
Failure Zone ◽  
Indentation Fracture ◽  
Depth Sensing ◽  
Indentation Fracture Toughness ◽  
Depth Curves

Nanoindentation is an effective way of finding mechanical properties at nanoscale. They are especially useful for thin films where elimination of the substrate effect is required. The mechanism is based upon depth sensing indentation based on Oliver and Pharr modeling. The load-depth curves as well as time on sample were analyzed. Indentation impulse was found to have significant contribution in the nature of failure zone during indentation. Fracture toughness was also related to time on the sample.

scholarly journals Microwave Sintering of SiAlON Ceramics with TiN Addition

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1345 ◽  
Author(s):  
Özgür Sevgi Canarslan ◽  
Roberto Rosa ◽  
Levent Köroğlu ◽  
Erhan Ayas ◽  
Alpagut Kara ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Vickers Hardness ◽  
Microwave Sintering ◽  
Single Mode ◽  
Nominal Composition ◽  
Indentation Fracture ◽  
Microwave Furnace ◽  
Indentation Fracture Toughness ◽  
Difference Time

α-β SiAlON/TiN composites with nominal composition of α:β = 25:75 were fabricated by microwave sintering. The effect of titanium nitride addition on the phases, microstructure, microwave absorption ability and mechanical properties (Vickers hardness and fracture toughness) of the SiAlON-based composites were studied. Finite Difference Time Domain (FDTD) software was used for the numerical simulation in order to assess the most suitable experimental setup. Sintering trials were performed in a single mode microwave furnace operating at 2.45 GHz and a power output of 660 W, for a reaction time of 30 min. SiC blocks were used as a susceptor to accelerate the microwave processing by hybrid heating, with reduced heat losses from the surface of the material of the α-β SiAlON/TiN composites. The optimum comprehensive mechanical properties, corresponding to a relative density of 96%, Vickers hardness of 12.98 ± 1.81 GPa and Vickers indentation fracture toughness of 5.52 ± 0.71 MPa.m1/2 were obtained at 850 °C when the content of TiN was 5 wt.%.

Local Mechanical Properties of SiC - TiNbC Composite and its Constituents

2016 ◽  
Vol 368 ◽  
pp. 158-161 ◽  
Author(s):  
Martin Fides ◽  
Alexandra Kovalčíková ◽  
Pavol Hvizdoš ◽  
Richard Sedlák ◽  
Roman Bystrický ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Elasticity Modulus ◽  
Indentation Fracture ◽  
Final Density ◽  
Indentation Fracture Toughness ◽  
The Individual ◽  
Composite Hardness ◽  
Load Size ◽  
Good Agreement

SiC based composite with 50 % of additives (Ti and NbC with ratio of 9:16) has been prepared. The microstructure, porosity, and chemical composition were studied using SEM equipped with EDS analyser. Local mechanical properties such a hardness and elastic modulus of individual components of the composite were investigated by nanoindentation using Berkovich indenter tip. Hardness and fracture toughness of studied material as a whole was evaluated by means of classic Vickers macroindentation. Indentation cracks were observed and their propagation was analyzed. It was shown that the present phases were distributed uniformly. Moreover, final density was satisfactory with porosity lower than 1 %. The individual constituents shown similar elasticity modulus (550 - 590 GPa). Hardness (HIT) exhibited very pronounced load-size effect. At 10 mN load, hardness was 42.33 GPa ± 1.1 GPa for SiC and 35.73 GPa ± 0.9 GPa for TiNbC, while at 500 mN the composite hardness was 27.61 GPa ± 0.505 GPa. It is in good agreement with macrohardness values, when 27.6 GPa and 25 GPa has been measured for 1 and 10 kg loads, respectively. Indentation fracture toughness was 3.3 MPa.m1/2 ± 0.22 MPa.m1/2. Electrical conductivity was measured by four point probes method and its value was 8.8×104 ± 0.3×104 Sm-1.

A Transparent and Tough β-Si3N4 Ceramic with a Whiskery Microstructure

2015 ◽  
Vol 655 ◽  
pp. 1-5
Author(s):  
Peng Xi Li ◽  
Hong Qiang Wang ◽  
Liu Cheng Gui ◽  
Jun Li ◽  
Hai Long Zhang ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Amorphous Phase ◽  
Hot Pressing ◽  
High Density ◽  
Indentation Fracture ◽  
Indentation Fracture Toughness ◽  
Resultant Material

The transparent β-Si3N4ceramic with a whisker-like microstructure was prepared by hot-pressing at 2000 °C for 26 h, with MgSiN2as an additive. The resultant material achieves the maximum transmittance of 70 % at the wavelength of about 2.5 μm and the transmittance value keeps higher than 60 % in the range of 700-4500 nm wavelength, which is attributed to the very small amount of the intergranular amorphous phase along with high density. The present transparent β-Si3N4ceramic exhibits an indentation fracture toughness of 7.2±0.3 MPa m1/2.

In Situ Preparation and Mechanical Properties of (ZrB2+ZrC)/Zr3[Al(Si)]4C6 Composites

2014 ◽  
Vol 602-603 ◽  
pp. 438-442
Author(s):  
Lei Yu ◽  
Jian Yang ◽  
Tai Qiu
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Bending Strength ◽  
Coefficient Of Thermal Expansion ◽  
Raw Materials ◽  
Linear Increase ◽  
Fine Grain ◽  
Fine Grain Strengthening ◽  
Uniform Microstructure

Fully dense (ZrB2+ZrC)/Zr3[Al (Si)]4C6 composites with ZrB2 content varying from 0 to 15 vol.% and fixed ZrC content of 10 vol.% were successfully prepared by in situ hot-pressing in Ar atmosphere using ZrH2, Al, Si, C and B4C as raw materials. With the increase of ZrB2 content, both the bending strength and fracture toughness of the composites increase and then decrease. The synergistic action of ZrB2 and ZrC as reinforcements shows significant strengthening and toughing effect to the Zr3[Al (Si)]4C6 matrix. The composite with 10 vol.% ZrB2 shows the optimal mechanical properties: 516 MPa for bending strength and 6.52 MPa·m1/2 for fracture toughness. With the increase of ZrB2 content, the Vickers hardness of the composites shows a near-linear increase from 15.3 GPa to 16.7 GPa. The strengthening and toughening effect can be ascribed to the unique mechanical properties of ZrB2 and ZrC reinforcements, the differences in coefficient of thermal expansion and modulus between them and Zr3[Al (Si)]4C6 matrix, fine grain strengthening and uniform microstructure derived by the in situ synthesis reaction.

Fabrication of Bi-Te Based Thermoelectric Semiconductors by Using Hybrid Powders

2005 ◽  
Vol 297-300 ◽  
pp. 875-880
Author(s):  
Cheol Ho Lim ◽  
Ki Tae Kim ◽  
Yong Hwan Kim ◽  
Dong Choul Cho ◽  
Young Sup Lee ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Single Crystals ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Figure Of Merit ◽  
Bending Strength ◽  
Mixing Ratio ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
P Type

P-type Bi0.5Sb1.5Te3 compounds doped with 3wt% Te were fabricated by spark plasma sintering and their mechanical and thermoelectric properties were investigated. The sintered compounds with the bending strength of more than 50MPa and the figure-of-merit 2.9×10-3/K were obtained by controlling the mixing ratio of large powders (PL) and small powders (PS). Compared with the conventionally prepared single crystal thermoelectric materials, the bending strength was increased up to more than three times and the figure-of-merit Z was similar those of single crystals. It is expected that the mechanical properties could be improved by using hybrid powders without degradation of thermoelectric properties.

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