scholarly journals Kinetic Analysis for High-Temperature Coarsening of γ″ Phase in Ni-Based Superalloy GH4169

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2096 ◽  
Author(s):  
Cheng Zhang ◽  
Liming Yu ◽  
Hui Wang
Keyword(s):  
Strengthening Phase ◽  
Long Term Stability ◽  
Diffusion Controlled ◽  
Coarsening Behavior ◽  
Before And After ◽  
Coarsening Kinetics ◽  
Kinetics Of ◽  
Coherent Relationship ◽  
Gh4169 Alloy

The growth of precipitates in Ni-based superalloy GH4169 is critical as it controls the mechanical properties and long-term stability of the alloy. In this paper, the coarsening behavior of the main strengthening phase γ″ in the temperature range from 800 °C to 900 °C is investigated. Two heat treatment steps, i.e., pre-precipitation of γ″ phase and coarsening of precipitates at high temperatures, were performed on the GH4169 alloy. It was found that there were three morphological forms of γ″ phase in chronological order: lip-shape, disc-shape, and irregular rectangle-shape with larger size. The coarsening kinetics of γ″ phase followed the Lifshitz-Slyozov-Wagner (LSW) time-law for diffusion-controlled growth, and the activation energies of γ″ phase before and after losing the coherent relationship with matrix were 261 kJ mol−1 and 271 kJ mol−1, respectively.

scholarly journals Potential of Advanced Consolidants for the Application on Sandstone Rocks: A Comparative Study

2019 ◽  
Author(s):  
Monika Remzova ◽  
Radek Zouzelka ◽  
Jaroslav Lukes ◽  
Jiri Rathousky
Keyword(s):  
Mechanical Strength ◽  
Mechanical Performance ◽  
Accelerated Weathering ◽  
Long Term Stability ◽  
Before And After ◽  
Application Potential ◽  
Degree Of Consolidation ◽  
Drilling Resistance

To achieve efficient and durable consolidation of weathered sandstone, the selection of a suitable consolidant is essential. To reasonably assess the suitability of different formulations, it is fundamental to compare their performance as a consolidant within a substrate, which reliably models the properties of deteriorated material. As a test substrate, the sandstone from quarries in Mšené in central Bohemia was selected, for its developed porosity and relatively low mechanical strength. To obtain relevant comparison of their application potential, both commercial (Remmers KSE OH and Surfapore) and self-developed consolidants were included. To test the long-term stability of each consolidant, the stone was subjected to accelerated weathering. The characterization of texture properties was based on the physical sorption of nitrogen and krypton, mercury intrusion porosimetry and water uptake. While the mechanical properties in microscale were determined by nanoindentation, the mechanical strength in macroscale before and after consolidation was measured by drilling resistance. Both commercial exhibited good mechanical performance with reasonable durability. The performance of our developed samples was comparable or, in some cases, superior. Very interesting were the consolidants containing TiO2 and ZnO nanoparticles, the former exhibiting comparable degree of consolidation and durability as commercial ones, with additional photocatalytic function, the latter unusually high increase in the mechanical strength, even after the weathering test. The diammonium hydrogen phosphate based consolidant showed exceptional durability in the weathering test, which makes it a promising product not only for carbonate but also sandstone materials.

Coarsening Kinetics of Grain Boundary in a Cast Nickel Base Superalloy during Long Term Aging

PRICM ◽  
2013 ◽  
pp. 317-325
Author(s):  
Qiang Zeng ◽  
Minghan Zhao ◽  
Ping Yan ◽  
Juntao Li ◽  
Jingchen Zhao ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Nickel Base Superalloy ◽  
Coarsening Kinetics ◽  
Nickel Base ◽  
Kinetics Of ◽  
Base Superalloy

The Effect of VikaneTm on the Stability of Cellulosic and Ligneous Materials -- Measurement of Deterioration by Chemical and Physical Methods

1990 ◽  
Vol 185 ◽  
Author(s):  
Helen D. Burgess ◽  
Nancy E. Binnie
Keyword(s):  
Hydrolytic Degradation ◽  
Degree Of Polymerization ◽  
Accelerated Ageing ◽  
Total Acid ◽  
Long Term Stability ◽  
Before And After ◽  
Pulp Fibres ◽  
General Scientific ◽  
The Stability

AbstractVikaneTM (sulphuryl fluoride) is a commercial fumigant[1] which is used for the control of pests in museum collections. This paper summarizes the results obtained through an investigation of the effect of VikaneTM on twenty-five paper and textile samples. Samples chosen were representative of artifacts present in North American collections (cotton, linen, jute, and wood pulp fibres, from 1622 to present).The effect of the fumigation treatment has been evaluated by chemical and physical analyses: (1) Acidity -- surface pH, cold extracted pH, total acid (iodometric titration), (2) Oxidative and Hydrolytic Degradation - viscometric average degree of polymerization, carbonyl content (hydrazone derivatization), (3) and Fumigant Residues (specific ion electrode). Analysis of unfumigated and fumigated samples was carried out before and after accelerated ageing (70°C and 50% relative humidity) in order to estimate the long term stability of fumigated samples.The data obtained show that commercial grade VikaneTM degrades cellulosic and ligneous fibres. A second set of experiments on two fibre types using a new experimental grade of VikaneTM gave significantly less degradation. The presentation of this work will concentrate upon a general scientific interpretation of results.It is anticipated that the conclusions will be applicable to a broad range of artifacts.

Unravelling the redox mechanism and kinetics of a highly active and selective Ni-based material during the oxidative dehydrogenation of ethane

2021 ◽  
Author(s):  
Carlos Alvarado-Camacho ◽  
Jeroen Poissonnier ◽  
Joris Thybaut ◽  
Carlos O. Castillo
Keyword(s):  
Oxidative Dehydrogenation ◽  
High Selectivity ◽  
Promising Alternative ◽  
Redox Mechanism ◽  
Long Term Stability ◽  
Highly Active ◽  
Ethane Oxidative Dehydrogenation ◽  
Mechanism And Kinetics ◽  
Kinetics Of

Ethane oxidative dehydrogenation (ODH-C2) is a promising alternative for producing ethylene. Even if SnO2-NiO catalysts are characterized by their long-term stability and high selectivity to ethylene, also in the absence...

Comparison of the Long-Term Stability of TiO2 Hydrosols with Different Concentration of Nanoparticles

2012 ◽  
Vol 77 ◽  
pp. 53-58 ◽  
Author(s):  
Olga Pavlova-Verevkina ◽  
Natalia Golubko ◽  
Alexander Sumbatov ◽  
Ludmila Ozerina
Keyword(s):  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Tio2 Nanoparticles ◽  
Hydrodynamic Radius ◽  
Slow Growth ◽  
Term Stability ◽  
Long Term Stability ◽  
The Mean ◽  
Kinetics Of

The long-term stability of two TiO2 hydrosols with concentration of TiO2 nanoparticles 1 and 12 mass.% was compared by turbidimetry and dynamic light scattering. The both sols were stabilized by HCl at pH=0.5. It was found that the mean hydrodynamic radius of particles and the turbidity of the sols increased slowly for six months of investigation and the kinetics of the “ageing” of the sols did not depend on TiO2 concentration. The obtained results will enable to determine mechanisms of the slow growth of nanoparticles and to modify nanoparticles structure.

scholarly journals Study on Mechanical Mechanism and Stability of Surrounding Rock in Fault Structure Roadway

2021 ◽  
Author(s):  
yuming lu ◽  
Wang Wei ◽  
Tang Zhiyu1
Keyword(s):  
Field Investigation ◽  
Surrounding Rock ◽  
Metal Mesh ◽  
Failure Characteristics ◽  
Deformation And Failure ◽  
Fault Structure ◽  
Long Term Stability ◽  
Before And After ◽  
Calculation Results

Abstract In order to study the deformation and failure mechanism of the fault passage, this paper makes a series of research on the fault passage through theoretical analysis, field investigation and numerical simulation. Firstly, the mechanical characteristics of the fault structure and the deformation and failure characteristics of the surrounding rock passing through the fault are summarized. Then, the numerical analysis is carried out before and after the tunnel passing through the fault. The results show that the original support scheme has large deformation and failure in the surrounding rock of the fault section, and the deterioration and expansion of the plastic zone leads to the failure of the support. Finally, the comprehensive support scheme and principle of "bolt + anchor cable + metal mesh + grouting" is put forward, and the support for the broken tunnel passing through the fault is strengthened. The calculation results show that the support scheme can keep the tunnel passing through the fault in a stable deformation range, which is conducive to the long-term stability of the surrounding rock.

Initiating crystal growth kinetics of α-HC(NH2)2PbI3 for flexible solar cells with long-term stability

Nano Energy ◽  
2016 ◽  
Vol 26 ◽  
pp. 438-445 ◽  
Author(s):  
Jun Xi ◽  
Zhaoxin Wu ◽  
Kai Xi ◽  
Hua Dong ◽  
Bin Xia ◽  
...  
Keyword(s):  
Solar Cells ◽  
Crystal Growth ◽  
Growth Kinetics ◽  
Term Stability ◽  
Long Term Stability ◽  
Crystal Growth Kinetics ◽  
Kinetics Of
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