Heat Curing and Delayed Ettringite Formation

1994 ◽  
Vol 370 ◽  
Author(s):  
M.C. Lewis ◽  
Karen L. Scrivener ◽  
S. Kelham
Keyword(s):  
Heat Treatment ◽  
Elevated Temperature ◽  
X Ray Diffraction ◽  
Delayed Ettringite Formation ◽  
X Ray ◽  
Preliminary Results ◽  
Ettringite Formation ◽  
Heat Curing ◽  
Xrd Studies ◽  
Over Time

AbstractThis paper reports some preliminary results from a study of the effect of elevated temperature curing on mortars and the phenomenon of delayed ettringite formation (DEF). Mortars made from cements with sulphate levels of 3%, 4%, and 5% and with 5% sulphate and added alkali were cured at 20 and 90° C and subsequently stored in water. Expansion measurements showed a pessimum effect with increasing S03 content. Mortars which expanded showed a corresponding decrease in strength. X-ray diffraction (XRD) studies indicated that no ettringite is present after heat treatment but re-forms over time within the material. However, the ultimate levels of ettringite reached do not correspond to the magnitude of expansion observed. X-ray microanalysis shows that immediately after the heat treatment the aluminate species and most of the sulphate species are incorporated within the C-S-H gel. The concentrations of these species decrease during expansion, such that at the end of expansion the amounts remaining correspond to the presence of AFm phase mixed with C-S-H.

Magnetization and XRD Studies of Laser Heat Treated SmCo5 Powders

2021 ◽  
Vol 1016 ◽  
pp. 1299-1304
Author(s):  
Naidu Seetala ◽  
Deidre Henderson ◽  
Jumel Jno-Baptiste ◽  
Hao Wen ◽  
Sheng Min Guo
Keyword(s):  
Heat Treatment ◽  
Hydrogen Gas ◽  
Vacuum Furnace ◽  
X Ray Diffraction ◽  
X Ray ◽  
Micro Particles ◽  
Laser Heat ◽  
Heat Treated ◽  
Xrd Studies ◽  
Hydride Phases

The microstructure and magnetization of SmCo5 micro-particles may be used as feedstock for 3D printing to make miniature strong magnets. Thus, the magnetic response and microstructures of commercially available SmCo5 micro-particles were studied under various heat treatments using a high wattage laser. The magnetization of laser heat treated powders at 50-watt showed an increase in magnetization, while the 75-watt melt showed a little to no change. Unfortunately, the coercivity of both laser heat treated samples decreased significantly. Oxidation during the heat treatment is suspected to result in low coercivity. Purging with argon-gas prior to laser heating showed improved coercivity. To further minimize the oxidation problem a set of SmCo5 powder was reduced prior to laser heat treatment using a constant flow of hydrogen gas while being heated at various temperatures from 100 oC to 400 oC for a period of ~4 hours. The results show that the magnetization generally increases with the temperature, while the coercivity decreases significantly. Another set of SmCo5 was annealed in a vacuum furnace for one hour at temperatures between 200 oC and 400 oC in order to confirm that no hydride phases were formed during reduction. The magnetization and coercivity showed similar variations with annealing temperature to those for the reduced powders confirming that these variations may be due to change in crystal structure rather than formation of hydrides. X-ray Diffraction (XRD) studies were performed to identify the changes in crystal phases.

scholarly journals Fractal Cracking Patterns in Concretes Exposed to Sulfate Attack

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2338 ◽  
Author(s):  
Jinwei Yao ◽  
Jiankang Chen ◽  
Chunsheng Lu
Keyword(s):  
Crack Nucleation ◽  
Fractal Dimensions ◽  
Sulfate Attack ◽  
Growth Patterns ◽  
X Ray Diffraction ◽  
Delayed Ettringite Formation ◽  
Crack Evolution ◽  
X Ray ◽  
Surface Cracking ◽  
Ettringite Formation

Sulfate attack tests were performed on concrete samples with three water-to-cement ratios, and micro-crack growth patterns on concrete surfaces were recorded. The expansive stress and crack nucleation caused by delayed ettringite formation (DEF) were studied using X-ray diffraction and scanning electron microscopy. By means of a digital image processing technology, fractal dimensions of surface cracking patterns were determined, which monotonously increase during corrosion. Moreover, it is shown that the change of fractal dimensions is directly proportional to accumulation of DEF, and therefore, a simple theoretical model could be proposed to describe the micro-crack evolution in concretes under sulfate attack.

scholarly journals X-ray Determination of Compressive Residual Stresses in Spring Steel Generated by High-Speed Water Quenching

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1154
Author(s):  
Diego E. Lozano ◽  
George E. Totten ◽  
Yaneth Bedolla-Gil ◽  
Martha Guerrero-Mata ◽  
Marcel Carpio ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stresses ◽  
High Speed ◽  
Spring Steel ◽  
X Ray Diffraction ◽  
Laboratory Equipment ◽  
X Ray ◽  
Water Chamber ◽  
Hardened Case ◽  
Compressive Residual Stresses

Automotive components manufacturers use the 5160 steel in leaf and coil springs. The industrial heat treatment process consists in austenitizing followed by the oil quenching and tempering process. Typically, compressive residual stresses are induced by shot peening on the surface of automotive springs to bestow compressive residual stresses that improve the fatigue resistance and increase the service life of the parts after heat treatment. In this work, a high-speed quenching was used to achieve compressive residual stresses on the surface of AISI/SAE 5160 steel samples by producing high thermal gradients and interrupting the cooling in order to generate a case-core microstructure. A special laboratory equipment was designed and built, which uses water as the quenching media in a high-speed water chamber. The severity of the cooling was characterized with embedded thermocouples to obtain the cooling curves at different depths from the surface. Samples were cooled for various times to produce different hardened case depths. The microstructure of specimens was observed with a scanning electron microscope (SEM). X-ray diffraction (XRD) was used to estimate the magnitude of residual stresses on the surface of the specimens. Compressive residual stresses at the surface and sub-surface of about −700 MPa were obtained.

scholarly journals Optical, XPS and XRD Studies of Semiconducting Copper Sulfide Layers on a Polyamide Film

2009 ◽  
Vol 2009 ◽  
pp. 1-8 ◽  
Author(s):  
Valentina Krylova ◽  
Mindaugas Andrulevičius
Keyword(s):  
Photoelectron Spectroscopy ◽  
Copper Sulfide ◽  
Diffusion Method ◽  
X Ray Diffraction ◽  
Xps Spectra ◽  
X Ray ◽  
Xrd Studies ◽  
Polyamide Film ◽  
Indirect Band Gap ◽  
Xrd Method

Copper sulfide layers were formed on polyamide PA 6 surface using the sorption-diffusion method. Polymer samples were immersed for 4 and 5 h in 0.15 mol⋅  solutions and acidified with HCl (0.1 mol⋅) at . After washing and drying, the samples were treated with Cu(I) salt solution. The samples were studied by UV/VIS, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) methods. All methods confirmed that on the surface of the polyamide film a layer of copper sulfide was formed. The copper sulfide layers are indirect band-gap semiconductors. The values of are 1.25 and 1.3 eV for 4 h and 5 h sulfured PA 6 respectively. Copper XPS spectra analyses showed Cu(I) bonds only in deeper layers of the formed film, while in sulfur XPS S 2p spectra dominating sulfide bonds were found after cleaning the surface with ions. It has been established by the XRD method that, beside , the layer contains as well. For PA 6 initially sulfured 4 h, grain size forchalcocite, , was  nm and fordjurleite, , it was 54.17 nm. The sheet resistance of the obtained layer varies from 6300 to 102 .

Heat treatment of fresh concrete by radio waves – Avoiding delayed ettringite formation

2017 ◽  
Vol 143 ◽  
pp. 580-588 ◽  
Author(s):  
Björn Höhlig ◽  
Christof Schröfl ◽  
Simone Hempel ◽  
Ina Noack ◽  
Viktor Mechtcherine ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Fresh Concrete ◽  
Radio Waves ◽  
Delayed Ettringite Formation ◽  
Ettringite Formation

Phase selection in precursor-derived yttrium aluminum garnet and related Al2O3–Y2O3 compositions

2005 ◽  
Vol 20 (4) ◽  
pp. 1017-1025 ◽  
Author(s):  
Ashutosh S. Gandhi ◽  
Carlos G. Levi
Keyword(s):  
Heat Treatment ◽  
Yttrium Aluminum Garnet ◽  
Lattice Parameter ◽  
Defect Structures ◽  
X Ray Diffraction ◽  
Phase Selection ◽  
X Ray ◽  
Yttrium Aluminum ◽  
Rich Side ◽  
Nitrate Solutions

Al2O3–Y2O3 powders were synthesized in the range of 25–55% Y2O3 by reverse coprecipitation of nitrate solutions. All starting powders were amorphous and formed primary yttrium aluminum garnet (YAG) upon crystallization. X-ray diffraction detected only garnet in compositions of 30–40% Y2O3 after heat treatment at 1250 °C. Compositions of 45–55% Y2O3 established a metastable YAG + Y4Al2O9 microstructure. The YAG phase field was metastably extended away from its stoichiometry, as indicated by a systematic increase in lattice parameter with Y2O3 content. Although some Al2O3 enrichment was achieved, YAG appears to tolerate greater off-stoichiometry on the Y2O3-rich side. Possible defect structures accommodating the solubility extension were examined. Phase selection results indicate that compositional inhomogeneity is not the only reason behind the appearance of hexagonal YAlO3, which is frequently reported during YAG synthesis.

In Situ X-Ray Diffraction Studies of Crystallization Growth Behavior in ZnO-Bi2O3-B2O3 Glass as a Route to Functional Optical Devices

MRS Advances ◽  
2018 ◽  
Vol 3 (11) ◽  
pp. 563-567 ◽  
Author(s):  
Quentin Altemose ◽  
Katrina Raichle ◽  
Brittani Schnable ◽  
Casey Schwarz ◽  
Myungkoo Kang ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Glass Ceramics ◽  
Treatment Temperature ◽  
Crystal Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
In Situ Xrd ◽  
Dsc Measurements ◽  
Transmission Window

ABSTRACTTransparent optical ZnO–Bi2O3–B2O3 (ZBB) glass-ceramics were created by the melt quenching technique. In this work, a melt of the glass containing stoichiometric ratios of Zn/Bi/B and As was studied. Differential scanning calorimeter (DSC) measurements was used to measure the thermal behavior. VIS/NIR transmission measurements were used to determine the transmission window. X-ray diffraction (XRD) was used to determine crystal phase. In this study, we explore new techniques and report a detailed study of in-situ XRD of the ZBB composition in order to correlate nucleation temperature, heat treatment temperature, and heat treatment duration with induced crystal phase.

TEM and X-Ray Examinations of Intermetallic Phases and Carbides Precipitation in an Fe-Ni Superalloy during Prolonged Ageing

2013 ◽  
Vol 212 ◽  
pp. 15-20
Author(s):  
Kazimierz J. Ducki ◽  
Jacek Mendala ◽  
Lilianna Wojtynek
Keyword(s):  
Heat Treatment ◽  
Solution Heat Treatment ◽  
Intermetallic Phase ◽  
Intermetallic Phases ◽  
Precipitation Process ◽  
Secondary Phases ◽  
X Ray Diffraction ◽  
Solid Samples ◽  
Structural Investigations ◽  
X Ray

The influence of prolonged ageing on the precipitation process of the secondary phases in an Fe-Ni superalloy of A-286 type has been studied. The samples were subjected to a solution heat treatment at 980°C for 2 h and water quenched, and then aged at temperatures of 715, 750 and 780°C at holding times from 0.5 to 500 h. Structural investigations were conducted using TEM and X-ray diffraction methods. The X-ray phase analyses performed on the isolates were obtained by anodic dissolution of the solid samples. After solution heat treatment the alloy has the structure of twinned austenite with a small amount of undissolved precipitates, such as carbide TiC, carbonitride TiC0.3N0.7, nitride TiN0.3, carbosulfide Ti4C2S2, Laves phase Ni2Si, and boride MoB. The application of ageing causes precipitation processes of γ-Ni3(Al,Ti), G (Ni16Ti6Si7), η (Ni3Ti), β (NiTi) and σ (Cr0.46Mo0.40Si0.14) intermetallic phases, as well as the carbide M23C6. It was found that the main phase precipitating during alloy ageing was the γ intermetallic phase.

Hardening of Selective Laser Melted M2 Steel

2021 ◽  
Author(s):  
Mei Yang ◽  
Yishu Zhang ◽  
Haoxing You ◽  
Richard Smith ◽  
Richard D. Sisson
Keyword(s):  
Heat Treatment ◽  
High Speed ◽  
Cutting Tools ◽  
High Speed Steel ◽  
High Hardness ◽  
Steel Part ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
Near Net Shape

Abstract Selective laser melting (SLM) is an additive manufacturing technique that can be used to make the near-net-shape metal parts. M2 is a high-speed steel widely used in cutting tools, which is due to its high hardness of this steel. Conventionally, the hardening heat treatment process, including quenching and tempering, is conducted to achieve the high hardness for M2 wrought parts. It was debated if the hardening is needed for additively manufactured M2 parts. In the present work, the M2 steel part is fabricated by SLM. It is found that the hardness of as-fabricated M2 SLM parts is much lower than the hardened M2 wrought parts. The characterization was conducted including X-ray diffraction (XRD), optical microscopy, Scanning Electron Microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) to investigate the microstructure evolution of as-fabricated, quenched, and tempered M2 SLM part. The M2 wrought part was heat-treated simultaneously with the SLM part for comparison. It was found the hardness of M2 SLM part after heat treatment is increased and comparable to the wrought part. Both quenched and tempered M2 SLM and wrought parts have the same microstructure, while the size of the carbides in the wrought part is larger than that in the SLM part.

scholarly journals Synchrotron Nano-Diffraction Study of Thermally Treated Asbestos Tremolite from Val d’Ala, Turin (Italy)

Minerals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 311 ◽  
Author(s):  
Carlotta Giacobbe ◽  
Jonathan Wright ◽  
Dario Di Giuseppe ◽  
Alessandro Zoboli ◽  
Mauro Zapparoli ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Heat Treatment ◽  
Risk Management ◽  
Structure Analysis ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
Adverse Health Effects ◽  
Nano Crystalline ◽  
Original Fibre

Nowadays, due to the adverse health effects associated with exposure to asbestos, its removal and thermal inertization has become one of the most promising ways for reducing waste risk management. Despite all the advances in structure analysis of fibers and characterization, some problems still remain that are very hard to solve. One challenge is the structure analysis of natural micro- and nano-crystalline samples, which do not form crystals large enough for single-crystal X-ray diffraction (SC-XRD), and their analysis is often hampered by reflection overlap and the coexistence of multiple fibres linked together. In this paper, we have used nano-focused synchrotron X-rays to refine the crystal structure of a micrometric tremolite fibres from Val d’Ala, Turin (Italy) after various heat treatment. The structure of the original fibre and after heating to 800 °C show minor differences, while the fibre that was heated at 1000 °C is recrystallized into pyroxene phases and cristobalite.

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