The Effects of Substitutional Additions on Creep Behavior of Tetragonal and Hexagonal Nb-Silicides

2002 ◽  
Vol 753 ◽  
Author(s):  
B. P. Bewlay ◽  
C. L. Briant ◽  
E. T. Sylven ◽  
M. R. Jackson
Keyword(s):  
Creep Behavior ◽  
High Strength ◽  
Aircraft Engine ◽  
Great Promise ◽  
Silicide Phase ◽  
Monolithic Phases ◽  
Phase Ordering ◽  
The Stability

ABSTRACTNb-silicide based in-situ composites combine a ductile Nb-based solid solution with high-strength silicides, and they show great promise for aircraft engine applications. The Nb-silicide controls the high-temperature creep behavior of the composite. Previous work has shown that the silicide composition has an important effect on the creep rate, with particular attention on the role of Ti and Hf additions. The aim of the present study is to understand the effects of the substitutional elements on the stability of the silicide phase, ordering in the crystal lattice, including the hP16-tI32 transition, and the creep behavior of the monolithic phases. To pursue this goal monolithic alloys with a range of compositions were prepared and the creep rates were measured at temperatures of 1100–1350°C. The stress sensitivities of the creep rates of the monolithic phases were also determined.

Creep Studies of Monolithic Phases in Nb-Silicide Based In-Situ Composites

2000 ◽  
Vol 646 ◽  
Author(s):  
B.P. Bewlay ◽  
C.L. Briant ◽  
E.T. Sylven ◽  
M.R. Jackson ◽  
G. Xiao
Keyword(s):  
Solid Solution ◽  
Creep Rate ◽  
Creep Resistance ◽  
High Strength ◽  
Aircraft Engine ◽  
Great Promise ◽  
In Situ Composites ◽  
Monolithic Phases ◽  
The Individual

ABSTRACTNb-silicide composites combine a ductile Nb-based solid solution with high-strength silicides, and they show great promise for aircraft engine applications. Previous work has shown that the silicide composition has an important effect on the creep rate. If the Nb:(Hf+Ti) ratio is reduced below ∼1.5, the creep rate increases significantly. This observation could be related to the type of silicide present in the material. To understand the effect of each phase on the composite creep resistance, the creep rates of selected monolithic phases were determined. To pursue this goal, monolithic alloys with compositions similar to the Nb-based solid solution and to the silicide phases, Laves, and T2 phases, were prepared. The creep rates were measured under compression at 1100 and 1200°C. The stress sensitivities of the creep rates of the monolithic phases were also determined. These results allow quantification of the load bearing capability of the individual phases in the Nb-silicide based in-situ composites.

scholarly journals Strength Optimization of Thermally Bonded Spunbond Nonwovens

2007 ◽  
Vol 2 (1) ◽  
pp. 155892500700200 ◽  
Author(s):  
Nataliya Fedorova ◽  
Svetlana Verenich ◽  
Behnam Pourdeyhimi
Keyword(s):  
Mechanical Properties ◽  
High Strength ◽  
Low Density Polyethylene ◽  
Great Promise ◽  
Thermal Bonding ◽  
Bicomponent Fibers ◽  
Nonwoven Materials ◽  
Fiber Technology ◽  
Bicomponent Fiber

Recent research on all aspects of thermally point bonded nonwovens has led to considerable improvements in the understanding of material requirements for these nonwovens, the changes that occur during bonding and the resultant deterioration of the mechanical properties of the nonwoven materials. This paper addresses how one may use a bicomponent fiber technology to overcome the shortcomings of the thermal bonding and obtain high strength spunbond fabrics. In particular, we present the utility of islands-in-the-sea (I/S) bicomponent fibers for optimizing the strength of thermally bonded fabrics. To examine the role of various bonding temperatures on the fabric performance, pre-consolidated webs were formed and subsequently, thermally bonded. Thus, any influence introduced by potential variations in the structure was minimized. Point-bonded bicomponent samples made up of nylon-6 (N6) as the islands and low density polyethylene (PE) as the sea showed great promise with respect to their mechanical properties, suggesting that the use of bicomponent fibers can be beneficial for strength optimization of thermally bonded spunbond nonwovens.

scholarly journals Fundamental Role Of The H2A.Z C-Terminal Tail In The Formation Of Constitutive Heterochromatin

2021 ◽  
Author(s):  
László Imre ◽  
Péter Nánási ◽  
Rosevalentine Bosire ◽  
Ágota Csóti ◽  
Kata Nóra Enyedi ◽  
...  
Keyword(s):  
Posttranslational Modifications ◽  
Constitutive Heterochromatin ◽  
Large Fraction ◽  
Gene Expression Pattern ◽  
Histone Variant ◽  
Unusual Behavior ◽  
Isoform Specificity ◽  
The Stability

ABSTRACTNucleosome stability, a crucial determinant of gene regulation, was measured in a robust in situ assay to assess the molecular determinants of the stability of H2A.Z-containig nucleosomes. Surprisingly, a large fraction of H2A.Z detected by three different antibodies was released from the nucleosomes by salt together with H3, and was associated with H3K9me3 but not with H3K27me3 marked nucleosomes. This unusual behavior relied on the presence of the unstructured C-terminal chain of the histone variant, rather than on isoform specificity, posttranslational modifications or binding of the reader protein PWWPA2, as determined using cell lines expressing only particular forms of the variant. In the absence of this tail, or upon addition of an excess of the tail peptide to the nuclei of control cells, the canonical H2A-like stability features were readily restored and most of the H2A.Z-containing nucleosomes left the periphery and ended up in scattered foci in the nuclei. Concomitantly, the H3K9me3-marked constitutive heterochromatin was also dispersed, what was accompanied by increased overall nuclease sensitivity and significantly enhanced binding of intercalating dyes to the DNA. The DT40 cells expressing the tailless H2A.Z showed marked differences in their gene expression pattern and were distinguished by compromised DNA damage response. Thus, interactions involving a short H2A.Z peptide chain simultaneously determine the stability and accessibility features of chromatin involving the nucleosomes containing this histone variant and the localization of these large chromatin regions in the nucleus. Our data suggest that H2A.Z can function in both heterochromatic and in euchromatic scenarios depending on the molecular interactions involving its C-terminal unstructured tail, shedding light on the enigmatic double-faced character of this histone variant.

scholarly journals LncRNA AC245100.4 binds HSP90 to promote the proliferation of prostate cancer

Epigenomics ◽  
2020 ◽  
Vol 12 (15) ◽  
pp. 1257-1271
Author(s):  
Rongjun Cui ◽  
Chi Liu ◽  
Ping Lin ◽  
Hui Xie ◽  
Wei Wang ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Cell Counting ◽  
Chaperone Function ◽  
In Vivo Assays ◽  
Iκb Kinase ◽  
Rna Immunoprecipitation ◽  
The Stability

Aim: To investigate the role and mechanisms of AC245100.4 in prostate cancer. Materials & methods: The expression and location of AC245100.4 were examined using real-time PCR and  in situ hybridization. Cell Counting Kit-8, clone formation, flow cytometry and in vivo assays were conducted to determine the role of AC245100.4. RNA antisense purification with mass spectrometry and RNA immunoprecipitation were performed to identify proteins that bind to AC245100.4. Western blotting was performed to quantify the expression of protein. Results: AC245100.4 expression was upregulated in prostate cancer and mainly located in the cytoplasm. Knockdown of AC245100.4 inhibited proliferation of prostate cancer. Mechanistically, AC245100.4 bound to HSP90 and altered its chaperone function, increased the stability of IκB kinase and activated the NFκB signaling pathway. Conclusion: AC245100.4 promotes the proliferation of prostate cancer via binding of HSP90.

In-Situ resistance Measurements During Rapid Thermal Annealing for Process Characterization

1995 ◽  
Vol 387 ◽  
Author(s):  
E. G. Colgan ◽  
C. Cabral ◽  
L. A. Clevenger ◽  
J. M. E. Harper
Keyword(s):  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Silicide Phase ◽  
Heating Rates ◽  
Process Characterization ◽  
Process Learning ◽  
Silicon Structures ◽  
The Stability ◽  
Kinetics Of

AbstractMeasurement of resistance in-situ during rapid thermal annealing is a powerful technique for process characterization and optimization. A major advantage of in-situ resistance measurements is the very rapid process learning. With silicides, in-situ resistance measurements can quickly determine an appropriate thermal process in which a low resistance silicide phase is formed without the agglomeration or inversion of silicide/polycrystalline silicon structures. One example is an optimized two step anneal for CoSi2 formation which was developed in less than one day. Examples of process characterization include determining the phase formation kinetics of TiSi2 (C49 and C54), Co2Si, and CoSi2 using in-situ ramped resistance measurements. The stability of TiSi2 or CoSi2/poly-Si structures has also been characterized by isothermal measurements. Resistance measurements have been made at heating rates from 1 to 100°C/s and temperatures up to 1000°C. The sample temperature was calibrated by melting Ag, Al, or Au/Si eutectics.

In-Situ Resistance Measurements During Rapid Thermal Annealing for Process Characterization

1995 ◽  
Vol 389 ◽  
Author(s):  
E.G. Colgan ◽  
C. Cabral ◽  
L.A. Clevenger ◽  
J.M.E. Harper
Keyword(s):  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Silicide Phase ◽  
Heating Rates ◽  
Process Characterization ◽  
Process Learning ◽  
Silicon Structures ◽  
The Stability ◽  
Kinetics Of

ABSTRACTMeasurement of resistance in-situ during rapid thermal annealing is a powerful technique for process characterization and optimization. A major advantage of in-situ resistance measurements is the very rapid process learning. With silicides, in-situ resistance measurements can quickly determine an appropriate thermal process in which a low resistance silicide phase is formed without the agglomeration or inversion of silicide/polycrystalline silicon structures. One example is an optimized two step anneal for CoSi2 formation which was developed in less than one clay. Examples of process characterization include determining the phase formation kinetics of TiSi2 (C49 and C54), Co2Si, and CoSi2 using in-situ ramped resistance measurements. The stability of TiSi2 or CoSi2/poly-Si structures has also been characterized by isothermal measurements. Resistance measurements have been made at heating rates from 1 to 100°C/s and temperatures up to 1000°C. The sample temperature was calibrated by melting Ag, Al, or Au/Si eutectics.

A Novel Temperature Induced Gelation Forming Method

2008 ◽  
Vol 368-372 ◽  
pp. 669-671
Author(s):  
Xin Xu ◽  
Ren Li Fu ◽  
José Maria F. Ferreira
Keyword(s):  
Particle Surface ◽  
Adsorbed Layer ◽  
High Strength ◽  
Suspended Particles ◽  
Green Body ◽  
Gelation Mechanism ◽  
In Situ Gelation ◽  
The Stability

We describe the production of complex shaped ceramic green bodies with high strength and reliability using a novel forming method: temperature-induced gelation. Gelation is performed by moderately decreasing the temperature of the suspension, which induces in situ gelation and forms a network to bridge the suspended particles, leading to a stiff green body. The gelation mechanism is based on the separation of dispersant KD1 from solvent or the collapse of adsorbed layer on particle surface, which depends on the stability of starting suspensions.

Revealing the role of phosphoric acid in all-vanadium redox flow batteries with DFT calculations and in situ analysis

2018 ◽  
Vol 20 (36) ◽  
pp. 23664-23673 ◽  
Author(s):  
Fabio Jonas Oldenburg ◽  
Marta Bon ◽  
Daniele Perego ◽  
Daniela Polino ◽  
Teodoro Laino ◽  
...  
Keyword(s):  
Phosphoric Acid ◽  
Negative Electrode ◽  
Vanadium Redox Flow Battery ◽  
Redox Flow Battery ◽  
Battery Electrolyte ◽  
The Stability ◽  
Vanadium Redox ◽  
Kinetics Of

Phosphoric acid improves the stability of vanadium redox flow battery electrolyte and enhances the kinetics of the negative electrode.

The Effects of Substitutional Additions on Tensile Behavior of Nb-Silicide Based Composites

2004 ◽  
Vol 842 ◽  
Author(s):  
Laurent Cretegny ◽  
Bernard P. Bewlay ◽  
Ann M. Ritter ◽  
Melvin R. Jackson
Keyword(s):  
Solid Solution ◽  
High Temperature ◽  
Room Temperature ◽  
High Strength ◽  
Aircraft Engine ◽  
Tensile Behavior ◽  
Strengthening Mechanisms ◽  
Temperature Capability ◽  
High Temperature Tensile

ABSTRACTNb-silicide based in-situ composites consist of a ductile Nb-based solid solution with high-strength silicides, and they show excellent promise for aircraft engine applications. The Nb-silicide controls the high-temperature tensile behavior of the composite, and the Nb solid solution controls the low and intermediate temperature capability. The aim of the present study was to understand the effects of substitutional elements on the room temperature tensile behavior and identify the principal microstructural features contributing to strengthening mechanisms.

Effect of Mo Addition on Microstructure and Properties of Nb/Nb5Si3 In-Situ Composite

2004 ◽  
Vol 449-452 ◽  
pp. 753-756 ◽  
Author(s):  
Wei Li ◽  
Hai Bo Yang ◽  
Ai Dang Shan ◽  
Jian Sheng Wu
Keyword(s):  
Fracture Toughness ◽  
Room Temperature ◽  
Metastable Phase ◽  
High Strength ◽  
High Fracture Toughness ◽  
High Fracture ◽  
Ductile Phase ◽  
Temperature Fracture ◽  
The Stability

Nb/Nb5Si3 in-situ composites are very attractive structural materials for these materials perform a good balance in mechanical properties, including a high strength at high temperature (>1373K) and reasonably high fracture toughness at room temperature. Metastable phase Nb3Si plays an important role in the properties of Nb/Nb5Si3 composites by affecting microstructure and volume fracture of ductile phase. In this paper, Nb-10Si-xMo and Nb-18Si-xMo (x=0,5,15) are prepared by arc melting and annealed at 1473K for 100h. Single edge-notched bending (SENB) test was used to study the fracture toughness of Nb-Si-Mo alloys. The stability of metastable phase is analyzed by XRD. The room temperature fracture toughness of Nb-10Si is 10.47MPa(m)1/2 and higher than that of binary Nb-18Si alloys at near-eutectic compositions. The addition of Mo improves the fracture toughness of as cast Nb-Si alloys from 4.1 MPa(m)1/2 to 9.9MPa(m)1/2 at near-eutectic compositions and decreases it from 10.47 MPa(m)1/2 to 8.8MPa(m)1/2 at hypoeutectic compositions.

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