Facile single-step ammonia heat-treatment and quenching process for the synthesis of improved Pt/N-graphene catalysts

2013 ◽  
Vol 266 ◽  
pp. 433-439 ◽  
Author(s):  
Bin Xiong ◽  
Yingke Zhou ◽  
Ryan O’Hayre ◽  
Zongping Shao
Keyword(s):  
Heat Treatment ◽  
Single Step ◽  
Quenching Process

Single-layer submicron-thick BaTiO3 coatings from poly(vinylpyrrolidone)-containing sols: Gel-to-ceramic film conversion, densification, and dielectric properties

2001 ◽  
Vol 16 (11) ◽  
pp. 3116-3123 ◽  
Author(s):  
Hiromitsu Kozuka ◽  
Atsushi Higuchi
Keyword(s):  
Heat Treatment ◽  
Condensation Reaction ◽  
Single Layer ◽  
Dip Coating ◽  
Single Step ◽  
Dielectric Constants ◽  
Isothermal Heat Treatment ◽  
Coating Films ◽  
Ceramic Film ◽  
C Decomposition

BaTiO3-coating films were prepared from a solution containing poly(vinylpyrrolidone) (PVP) of molar composition Ba(CH3COO)2:Ti(OC2H5)4:PVP:CH3COOH:H2O: C2H5OH = 1:1:0.5:27:4:5, via nonrepetitive, single-step dip-coating. The gel films were found to be converted into BaTiO3 films via evaporation of the solvent and CH3COOH below 210 °C, decomposition of PVP at 210–360 °C, decomposition of CH3COO− below 440 °C, and crystallization at 500–610 °C. The decomposition of PVP was accompanied by the progress of the condensation reaction, which resulted in significant reduction in film thickness. When the gel films were heated isothermally at 700 °C, crack-free BaTiO3 films as thick as 0.9 μm were obtained. When the gel films were heated isothermally at 360 °C and then at 700 °C, the film became denser. Higher dielectric constants around 290 were found for the film that underwent the isothermal heat treatment at 360 °C. A slower rate of PVP decomposition was thought to be the key for the film densification.

On the Influence of a Heat Treat for an Aluminizing Progress Based on Al Microparticles Slurry for Model Ni and Ni20Cr. Experimental and Theoretical Approaches.

2012 ◽  
Vol 323-325 ◽  
pp. 373-379 ◽  
Author(s):  
B. Rannou ◽  
M. Mollard ◽  
B. Bouchaud ◽  
J. Balmain ◽  
G. Bonnet ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Substrate Surface ◽  
Single Step ◽  
Alloying Element ◽  
Aluminum Particles ◽  
New Approach ◽  
Theoretical Approaches ◽  
Barrier Coating ◽  
Coating Characteristics ◽  
Good Agreement

The use of thermal barrier coating systems allows superalloys to withstand higher operating temperatures in aeroengine turbines. Aiming at providing oxidation protection to such substrates, an aluminum-rich layer is deposited to form the α-Al2O3scale over which a ceramic layer (i.e. YSZ layer) is applied to provide thermal insulation. A new approach is now being investigated within the FP7 European project « PARTICOAT », in which a single step process is employed by applying micro-sized aluminum particles. The particles are mixed in a binder and deposited by brushing or spraying on the substrate surface. During a heat treatment, the particles sinter and oxidize to form a top coat composed of hollow con-joint alumina spheres and simultaneously, an Al-rich diffusion zone is formed in the substrate. For a better understanding of the diffusion / growth processes, preliminary tests were carried out on pure nickel and Ni20Cr model alloys prior to further application on commercial superalloys. The effect of the heat treatment on the coating characteristics (number of layers, thickness, composition, homogeneity, etc.) was particularly investigated to emphasize the mechanisms of diffusion governing the growth of the coatings. The establishment of the diffused layers occurred very readily even at intermediate temperatures (650 and 700°C). However, the layers formed did not match perfectly with the thermodynamic modeling because of the quick incorporation of Ni into molten Al at intermediate temperatures (650°C). In contrast, at higher temperatures (700 and 1100°C) the phases predicted by Thermocalc are in good agreement with the observed thickness of the diffused layers. The incorporation of Cr as an alloying element restrained Al ingress by segregation of Cr even at very low temperatures aluminizing temperatures (625°C).

Uphill Quenching of Aluminum Alloys

2019 ◽  
Author(s):  
Wellington da Silva Mattos ◽  
George Edward Totten ◽  
Lauralice de Campos Franceschini Canale
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Residual Stress ◽  
Aluminum Alloys ◽  
Temperature Gradient ◽  
Dimensional Stability ◽  
Steam Chamber ◽  
Conventional Heat Treatment ◽  
Quenching Process ◽  
Uphill Quenching

This article describes the concept of uphill quenching process applied in the heat treatment of aluminum alloys. Uphill quenching is interesting since residual stress reductions of up to 80% has been reported. In addition, substantial improvements in dimensional stability have been achieved for several types of aluminum parts. Often, uphill quenching is applied after quenching and before aging during the heat treatment of aluminum alloys. The uphill quenching process consists of the immersion of the part in a cryogenic environment, and after homogenization of the temperature, the part is transferred to the hot steam chamber to obtain a temperature gradient that will maintain the mechanical properties gained with this process. The results obtained are lower residual stress and better dimensional stability. The aim of this article is to provide a review of this process and to compare it with conventional heat treatment.

scholarly journals Pengaruh Perlakuan Panas Quenching dan Tempering terhadap Laju Korosi pada Baja AISI 420

2017 ◽  
Vol 1 (2) ◽  
pp. 19
Author(s):  
Sotya Anggoro
Keyword(s):  
Heat Treatment ◽  
Stainless Steel ◽  
Corrosion Rate ◽  
Base Material ◽  
Air Cooling ◽  
Corrosion Resistant ◽  
A Value ◽  
Aisi 420 ◽  
Quenching Process ◽  
Cooling Media

<p>Corrosion occurs in almost all metals. Even corrosion-resistant metals are corroded, but their corrosion rate is different from ordinary or non-corrosion resistant metals. This study examines the corrosion rate that occurs in stainless steel that is stainless steel. Stainless steel contains high enough chromium levels that can reduce the rate of corrosion that occurs. The metal material to be studied is the AISI 420 steel, which belongs to the Martensitic Stainless Steel class. This study examined the effect of heat treatment on corrosion rate and hardness level of AISI 420 steel. The heat treatment carried out was Quenching at 1020<sup>o</sup>C with a holding time of 60minutes with an oil cooling medium. After quenching the subsequent heat treatment is tempering with temperature variations of temperature 200<sup>o</sup>C and 300<sup>o</sup>C with a resistance time of 45 minutes and air cooling media. The results of this study showed that the base material specimens had the highest corrosion rate of 0.569 mm/y. The lowest corrosion rate is in specimens with quenching process with a value of 0.267 mm/y. The highest Vickers hardness values were found in specimens with quenching process with a value of 551 kg/mm<sup>2</sup>. The lowest hardness value is in the specimen with tempering process at 300<sup>o</sup>C with 405 kg/mm<sup>2</sup>.</p>

Effect of Double-Step Solution Treatment on Rejuvenation Heat Treated Microstructure of IN-738 Superalloy

2020 ◽  
Vol 856 ◽  
pp. 36-42
Author(s):  
Chuleeporn Paa-Rai
Keyword(s):  
Heat Treatment ◽  
Image Analysis ◽  
Electron Microscope ◽  
Solution Treatment ◽  
Single Step ◽  
Double Step ◽  
Heat Treated ◽  
Cast Superalloy ◽  
Scanning Electron

This work investigates the effect of rejuvenation heat treatment, with double-step solution treatment at the temperature from 1150 °C to 1200 °C, on the recovered microstructure of IN-738 cast superalloy. The superalloy has been long-term exposed as a turbine blade in a gas turbine prior to this study. After double solution treatment and aging at 845 °C for 12 h and 24 h, the recovered microstructures were examined by using a scanning electron microscope. Coarse γ΄ particles, that have presented in damaged microstructures, could not be observed in the samples after the rejuvenation heat treatment. In addition, the image analysis illustrates that the reprecipitated γ΄ particles in the samples with double-step solution treatments increase significantly in sizes during aging than that in the samples with the single-step solution treatment. Furthermore, the measurement of the samples hardness presents that the as-receive sample hardness is improved after rejuvenation heat treatment studied in this work.

Effect of Non-Conventional Aging Treatments on the Tensile Properties of Non-Hipped Castings of Aluminum Alloy 354

2014 ◽  
Vol 875-877 ◽  
pp. 1397-1405 ◽  
Author(s):  
G. Dinesh Babu ◽  
M. Nageswara Rao
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Aluminum Alloy ◽  
Tensile Properties ◽  
Artificial Aging ◽  
Natural Aging ◽  
Single Step ◽  
Cast Aluminum Alloy ◽  
Cast Aluminum ◽  
Automobile Components

Cast aluminum alloy 354 is used extensively for production of critical automobile components, owing to its excellent castability and attractive combination of mechanical properties after heat-treatment. With the advent of higher performance engines, there has been a steady demand to further improve the mechanical behavior of the castings made of the alloy, among others, through improvements in processing. The present study explores the possibility of improving tensile properties of the alloy by adopting certain non-conventional aging treatments. The non-conventional treatments include aging cycles similar to T6I4 and T6I6 referred to in the published literature, artificial aging in two steps instead of in single step and artificial aging preceded by various natural aging times. The results show that none of these non-conventional treatments leads to improvement of all tensile properties compared to the standard T61 treatment. Significant hardening takes place in the alloy due to natural aging. Changing the time of natural aging preceding artificial aging was found to have little effect on tensile properties.

scholarly journals Investigation of a partial, inductive short-time heat treatment of thin metal sheets integrated into the forming process

2018 ◽  
Vol 190 ◽  
pp. 12008
Author(s):  
Benjamin Clausius ◽  
Petra Maier
Keyword(s):  
Heat Treatment ◽  
Strain Hardening ◽  
Sheet Thickness ◽  
Local Strain ◽  
Single Step ◽  
Thin Metal ◽  
Recrystallization Annealing ◽  
Forming Process ◽  
Metal Sheets ◽  
Short Time

Flanging is a widespread method in the sheet metal working industry to connect same or different materials by forming. Especially the sealing technology makes high demands on the flanging process: a low sheet thickness of the inner eyelet is necessary for proper sealing. The outer edges of the neck rings are mostly manufactured by shear cutting. The quality of the cut surface and the level of the local strain hardening influence decisively the limit of the flanging process by possible cracking. This paper is focused on the dependencies of these factors regarding thin metal sheets of different materials with a thickness down to 100 μm. It could be shown that strain hardening has a stronger effect on the process limits compared to the notch effect of the sheet edges when using standard values for the clearance of the shear cutting tool. Furthermore, a process is investigated with a partial inductive short-time heat treatment of the most deformed edge area. Due to the low thickness of the material and low heat capacities related thereto, it is possible to integrate a recrystallization annealing as single step into the forming process. As a result, the strain hardening can be removed from the affected zone directly between two forming steps to increase the process limits.

Investigation of Acoustic Signals During W1 Tool Steel Quenching

2015 ◽  
Author(s):  
Chetan P. Nikhare ◽  
Ihab Ragai ◽  
David Loker ◽  
Shannon Sweeney ◽  
Chris Conklin ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Tool Steel ◽  
Acoustic Emissions ◽  
Treatment Temperature ◽  
Carbon Steels ◽  
Design Parameters ◽  
Fluid Medium ◽  
Audible Sound ◽  
Quenching Process ◽  
Sound Signature

Quenching is an important part of the heat treatment process for strengthening medium and high carbon steels. In the heat treatment cycle, the metal is heated to a desired temperature (above the eutectoid temperature) in the furnace and then cooled in a fluid medium such as water, brine, oil or air. Depending on the cooling rate, the mechanical and metallurgical properties of the metal can be altered in order to achieve the specific design parameters that are required by the part. The process in which the metal is cooled rapidly is termed the quenching process. Due to rapid cooling in a medium, such as water, brine, or oil, the quenching process produces an audible sound signature, as well as, acoustic emissions. In this paper, W1 tool steel is investigated through the use of a beam former that is equipped with 32 microphones. Using this device, it is demonstrated that the audible sounds that are produced when quenching depend on the heat treatment temperature and the size of the specimen.

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