Implications of Diffusion on the Composition and Microstructures of Platinum Modified Aluminide Coatings on CMSX-4 Single Crystal Superalloy

2009 ◽  
Vol 289-292 ◽  
pp. 277-284 ◽  
Author(s):  
F. Pedraza
Keyword(s):  
Heat Treatment ◽  
High Pressure ◽  
Chemical Stability ◽  
Concentration Gradient ◽  
Diffusion Coefficients ◽  
State Of The Art ◽  
Metal Particles ◽  
Aluminide Coatings ◽  
Refractory Elements ◽  
Processing Steps

State-of-the-art aluminide coatings for high pressure aeroturbines rely on their chemical stability through the addition of platinum. In this work, the influence of diffusion on the composition and microstructure of Pt/Al coatings is investigated upon the different processing steps. Upon heat treatment of the electrodeposited Pt layers, the ready solubility of Pt in the ’-Ni3Al and its concentration gradient allow fast ingress of this element in the coating in spite of the higher diffusion coefficients of the substrate elements. The relatively high Pt contents at the surface thereafter promote Al ingress upon aluminisation by creating a greater concentration gradient between the coating atmosphere and the coating. This results in a -NiAl based coating grown by both Ni outward and Al inward diffusion. The diffusivity of Pt, Ni and Al being dependant on the stoichiometry of the -NiAl coating, different metal particles may precipitate mainly at the NiAl grain boundaries. In addition, the diffusion of the refractory elements towards the interdiffusion layer seems to be hurdled by increasing the Pt content. As a result of the countercurrent diffusion of species, different microstructures and compositions will appear across the coatings.

Xylooligosaccharides and their chemical stability under high-pressure processing combined with heat treatment

2021 ◽  
pp. 107167
Author(s):  
Eric Keven Silva ◽  
Henrique S. Arruda ◽  
Srujana Mekala ◽  
Glaucia M. Pastore ◽  
Maria Angela A. Meireles ◽  
...  
Keyword(s):  
Heat Treatment ◽  
High Pressure ◽  
Chemical Stability ◽  
High Pressure Processing

Revisiting the High-Pressure Properties of the Metal-Organic Frameworks ZIF-8 and ZIF-67

2020 ◽  
Author(s):  
Pia Vervoorts ◽  
Stefan Burger ◽  
Karina Hemmer ◽  
Gregor Kieslich
Keyword(s):  
High Pressure ◽  
State Of The Art ◽  
Energy Landscape ◽  
Structural Flexibility ◽  
Zeolitic Imidazolate Frameworks ◽  
Stimuli Responsive ◽  
X Ray Diffraction ◽  
X Ray ◽  
Open Questions ◽  
Metal Organic

The zeolitic imidazolate frameworks ZIF-8 and ZIF-67 harbour a series of fascinating stimuli responsive properties. Looking at their responsitivity to hydrostatic pressure as stimulus, open questions exist regarding the isotropic compression with non-penetrating pressure transmitting media. By applying a state-of-the-art high-pressure powder X-ray diffraction setup, we revisit the high-pressure behaviour of ZIF-8 and ZIF-67 up to <i>p</i> = 0.4 GPa in small pressure increments. We observe a drastic, reversible change of high-pressure powder X-ray diffraction data at <i>p</i> = 0.3 GPa, discovering large volume structural flexibility in ZIF-8 and ZIF-67. Our results imply a shallow underlying energy landscape in ZIF-8 and ZIF-67, an observation that might point at rich polymorphism of ZIF-8 and ZIF-67, similar to ZIF-4(Zn).<br>

Revisiting the High-Pressure Properties of the Metal-Organic Frameworks ZIF-8 and ZIF-67

2020 ◽  
Author(s):  
Pia Vervoorts ◽  
Stefan Burger ◽  
Karina Hemmer ◽  
Gregor Kieslich
Keyword(s):  
High Pressure ◽  
State Of The Art ◽  
Energy Landscape ◽  
Structural Flexibility ◽  
Zeolitic Imidazolate Frameworks ◽  
Stimuli Responsive ◽  
X Ray Diffraction ◽  
X Ray ◽  
Open Questions ◽  
Metal Organic

The zeolitic imidazolate frameworks ZIF-8 and ZIF-67 harbour a series of fascinating stimuli responsive properties. Looking at their responsitivity to hydrostatic pressure as stimulus, open questions exist regarding the isotropic compression with non-penetrating pressure transmitting media. By applying a state-of-the-art high-pressure powder X-ray diffraction setup, we revisit the high-pressure behaviour of ZIF-8 and ZIF-67 up to <i>p</i> = 0.4 GPa in small pressure increments. We observe a drastic, reversible change of high-pressure powder X-ray diffraction data at <i>p</i> = 0.3 GPa, discovering large volume structural flexibility in ZIF-8 and ZIF-67. Our results imply a shallow underlying energy landscape in ZIF-8 and ZIF-67, an observation that might point at rich polymorphism of ZIF-8 and ZIF-67, similar to ZIF-4(Zn).<br>

Comparison of Ricotta cheese made by high pressure treatment with that produced by heat treatment of sweet whey

2002 ◽  
Vol 22 (5) ◽  
pp. 601-615 ◽  
Author(s):  
Souhail Besbes ◽  
Christophe Blecker ◽  
Hamadi Attia ◽  
Carine Massaux ◽  
Claude Deroanne
Keyword(s):  
Heat Treatment ◽  
High Pressure ◽  
Pressure Treatment ◽  
High Pressure Treatment ◽  
Sweet Whey

scholarly journals Chemical Stability of FeOOH at High Pressure and Temperature, and Oxygen Recycling in Early Earth History

2021 ◽  
Author(s):  
Egor Koemets ◽  
Timofey Fedotenko ◽  
Saiana Khandarkhaeva ◽  
Maxim Bykov ◽  
Elena Bykova ◽  
...  
Keyword(s):  
High Pressure ◽  
Chemical Stability ◽  
Early Earth ◽  
High Pressure And Temperature ◽  
Earth History

Chemical stability of FeOOH at high pressure and temperature, and oxygen recycling in early Earth history

2021 ◽  
Author(s):  
Egor Koemets ◽  
Timofey Fedotenko ◽  
Saiana Khandarkhaeva ◽  
Maxim Bykov ◽  
Elena Bykova ◽  
...  
Keyword(s):  
High Pressure ◽  
Chemical Stability ◽  
Early Earth ◽  
High Pressure And Temperature ◽  
Earth History

scholarly journals Cavitation patterns in high-pressure homogenization nozzles with cylindrical orifices: Influence of mixing stream in Simultaneous Homogenization and Mixing

2021 ◽  
Author(s):  
V. Gall ◽  
E. Rütten ◽  
H. P. Karbstein
Keyword(s):  
High Pressure ◽  
Process Design ◽  
High Speed ◽  
State Of The Art ◽  
Back Pressure ◽  
High Pressure Homogenization ◽  
Unit Operation ◽  
Mixing Chamber ◽  
Cavitation Intensity ◽  
Droplet Sizes

AbstractHigh-pressure homogenization is the state of the art to produce high-quality emulsions with droplet sizes in the submicron range. In simultaneous homogenization and mixing (SHM), an additional mixing stream is inserted into a modified homogenization nozzle in order to create synergies between the unit operation homogenization and mixing. In this work, the influence of the mixing stream on cavitation patterns after a cylindrical orifice is investigated. Shadow-graphic images of the cavitation patterns were taken using a high-speed camera and an optically accessible mixing chamber. Results show that adding the mixing stream can contribute to coalescence of cavitation bubbles. Choked cavitation was observed at higher cavitation numbers σ with increasing mixing stream. The influence of the mixing stream became more significant at a higher orifice to outlet ratio, where a hydraulic flip was also observed at higher σ. The decrease of cavitation intensity with increasing back-pressure was found to be identical with conventional high-pressure homogenization. In the future, the results can be taken into account in the SHM process design to improve the efficiency of droplet break-up by preventing cavitation or at least hydraulic flip.

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