Carbide formation during isothermal, decomposition of alloyed austenite in hypereutectoid steels

1959 ◽  
Vol 1 (2) ◽  
pp. 23-26
Author(s):  
I. S. Anitov
Keyword(s):  
Carbide Formation ◽  
Isothermal Decomposition ◽  
Hypereutectoid Steels ◽  
Alloyed Austenite

Characterization of carbides in M50NiL

1991 ◽  
Vol 49 ◽  
pp. 606-607
Author(s):  
L. S. Lin ◽  
K. P. Gumz ◽  
A. V. Karg ◽  
C. C. Law
Keyword(s):  
Temperature Effects ◽  
Base Composition ◽  
Lattice Parameter ◽  
Control Surface ◽  
Carbide Formation ◽  
Particle Sizes ◽  
Low Carbon ◽  
Fee Structure ◽  
Heat Treated

Carbon and temperature effects on carbide formation in the carburized zone of M50NiL are of great importance because they can be used to control surface properties of bearings. A series of homogeneous alloys (with M50NiL as base composition) containing various levels of carbon in the range of 0.15% to 1.5% (in wt.%) and heat treated at temperatures between 650°C to 1100°C were selected for characterizations. Eleven samples were chosen for carbide characterization and chemical analysis and their identifications are listed in Table 1.Five different carbides consisting of M6C, M2C, M7C3 and M23C6 were found in all eleven samples examined as shown in Table 1. M6C carbides (with least carbon) were found to be the major carbide in low carbon alloys (<0.3% C) and their amounts decreased as the carbon content increased. In sample C (0.3% C), most particles (95%) encountered were M6C carbide with a particle sizes range between 0.05 to 0.25 um. The M6C carbide are enriched in both Mo and Fe and have a fee structure with lattice parameter a=1.105 nm (Figure 1).

Carbide formation during laser welding of SiC/aluminum composites

1993 ◽  
Author(s):  
Santosh Gopinathan ◽  
Narendra B. Dahotre ◽  
Mary Helen McCay ◽  
T. Dwayne McCay
Keyword(s):  
Laser Welding ◽  
Carbide Formation ◽  
Aluminum Composites

scholarly journals In-Situ Synchrotron X-ray Diffraction Investigation of Microstructural Evolutions During Low-Pressure Carburizing

2021 ◽  
Author(s):  
Ogün Baris Tapar ◽  
Jérémy Epp ◽  
Matthias Steinbacher ◽  
Jens Gibmeier
Keyword(s):  
Carbon Content ◽  
Carbon Diffusion ◽  
Low Pressure ◽  
Carbon Accumulation ◽  
Experimental Chamber ◽  
Carbide Formation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Carbon Supply

AbstractAn experimental heat treatment chamber and control system were developed to perform in-situ X-ray diffraction experiments during low-pressure carburizing (LPC) processes. Results from the experimental chamber and industrial furnace were compared, and it was proven that the built system is reliable for LPC experiments. In-situ X-ray diffraction investigations during LPC treatment were conducted at the German Electron Synchrotron Facility in Hamburg Germany. During the boost steps, carbon accumulation and carbide formation was observed at the surface. These accumulation and carbide formation decelerated the further carbon diffusion from atmosphere to the sample. In the early minutes of the diffusion steps, it is observed that cementite content continue to increase although there is no presence of gas. This effect is attributed to the high carbon accumulation at the surface during boost steps which acts as a carbon supply. During quenching, martensite at higher temperature had a lower c/a ratio than later formed ones. This difference is credited to the early transformation of austenite regions having lower carbon content. Also, it was noticed that the final carbon content dissolved in martensite reduced compared to carbon in austenite before quenching. This reduction was attributed to the auto-tempering effect.

scholarly journals Non-Isothermal Decomposition as Efficient and Simple Synthesis Method of NiO/C Nanoparticles for Asymmetric Supercapacitors

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 187
Author(s):  
Daria Chernysheva ◽  
Ludmila Pudova ◽  
Yuri Popov ◽  
Nina Smirnova ◽  
Olga Maslova ◽  
...  
Keyword(s):  
Nickel Oxide ◽  
Synthesis Method ◽  
Average Diameter ◽  
Carbon Support ◽  
Spherical Particles ◽  
Support Surface ◽  
Isothermal Decomposition ◽  
Step Method ◽  
Nickel Oxide Nanoparticles ◽  
Electrode Cell

A series of NiO/C nanocomposites with NiO concentrations ranging from 10 to 90 wt% was synthesized using a simple and efficient two-step method based on non-isothermal decomposition of Nickel(II) bis(acetylacetonate). X-ray diffraction (XRD) measurements of these NiO/C nanocomposites demonstrate the presence of β-NiO. NiO/C nanocomposites are composed of spherical particles distributed over the carbon support surface. The average diameter of nickel oxide spheres increases with the NiO content and are estimated as 36, 50 and 205 nm for nanocomposites with 10, 50 and 80 wt% NiO concentrations, respectively. In turn, each NiO sphere contains several nickel oxide nanoparticles, whose average sizes are 7–8 nm. According to the tests performed using a three-electrode cell, specific capacitance (SC) of NiO/C nanocomposites increases from 200 to 400 F/g as the NiO content achieves a maximum of 60 wt% concentration, after which the SC decreases. The study of the NiO/C composite showing the highest SC in three- and two-electrode cells reveals that its SC remains almost unchanged while increasing the current density, and the sample demonstrates excellent cycling stability properties. Finally, NiO/C (60% NiO) composites are shown to be promising materials for charging quartz clocks with a power rating of 1.5 V (30 min).

Carbide formation in the niobium-microalloyed 15Kh2MFA steel during heat treatment

2020 ◽  
Author(s):  
V. G. Teplukhin ◽  
A. S. Tsvetkov ◽  
A. I. Popov ◽  
D. N. Shabalin
Keyword(s):  
Heat Treatment ◽  
Carbide Formation ◽  
15Kh2mfa Steel

scholarly journals Influence of Phase Composition and Pretreatment on the Conversion of Iron Oxides into Iron Carbides in Syngas Atmospheres

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 773
Author(s):  
Aleks Arinchtein ◽  
Meng-Yang Ye ◽  
Michael Geske ◽  
Marvin Frisch ◽  
Ralph Kraehnert
Keyword(s):  
Phase Composition ◽  
Iron Oxide ◽  
Self Assembly ◽  
Iron Carbide ◽  
Active Phase ◽  
Physicochemical Analysis ◽  
Carbide Formation ◽  
Iron Carbides ◽  
Carbide Phases ◽  
Higher Hydrocarbons

CO2 Fischer–Tropsch synthesis (CO2–FTS) is a promising technology enabling conversion of CO2 into valuable chemical feedstocks via hydrogenation. Iron–based CO2–FTS catalysts are known for their high activities and selectivities towards the formation of higher hydrocarbons. Importantly, iron carbides are the presumed active phase strongly associated with the formation of higher hydrocarbons. Yet, many factors such as reaction temperature, atmosphere, and pressure can lead to complex transformations between different oxide and/or carbide phases, which, in turn, alter selectivity. Thus, understanding the mechanism and kinetics of carbide formation remains challenging. We propose model–type iron oxide films of controlled nanostructure and phase composition as model materials to study carbide formation in syngas atmospheres. In the present work, different iron oxide precursor films with controlled phase composition (hematite, ferrihydrite, maghemite, maghemite/magnetite) and ordered mesoporosity are synthesized using the evaporation–induced self–assembly (EISA) approach. The model materials are then exposed to a controlled atmosphere of CO/H2 at 300 °C. Physicochemical analysis of the treated materials indicates that all oxides convert into carbides with a core–shell structure. The structure appears to consist of crystalline carbide cores surrounded by a partially oxidized carbide shell of low crystallinity. Larger crystallites in the original iron oxide result in larger carbide cores. The presented simple route for the synthesis and analysis of soft–templated iron carbide films will enable the elucidation of the dynamics of the oxide to carbide transformation in future work.

Nanozirconium Carbide Powder Synthesis via Carbothermal Route

2013 ◽  
Vol 334-335 ◽  
pp. 381-386 ◽  
Author(s):  
F. Arianpour ◽  
F. Kazemi ◽  
Hamid Reza Rezaie ◽  
A. Asjodi ◽  
J. Liu
Keyword(s):  
Carbon Sources ◽  
Zirconium Carbide ◽  
Carbide Powder ◽  
Carbide Formation ◽  
Matrix Composites ◽  
Powder Synthesis ◽  
High Refractoriness ◽  
Heat Treated ◽  
Crystallite Sizes ◽  
20 Nm

Zirconium carbide (ZrC) has extended application in many ceramic and metal matrix composites especially used for ultra high temperature conditions. The synthesis of zirconium carbide powder is costly and difficult because of its high refractoriness and chemically inert properties. In this research, the synthesis of zirconium carbide nanopowder at low temperature via carbothermal reduction route was investigated according to thermodynamic data. The starting materials were zirconium acetate and sucrose as zirconium and carbon sources, respectively. After preparation of different carbon/zirconium ratio containing precursors, the dried precursors were heat treated at 1400°C and vacuum atmosphere. Also the ZrC formation was followed by thermal analysis of the produced precursors. The phase evolutions and microstructural studies were carried out using X-ray diffraction and scanning electron microscopy. The results showed that it is possible to synthesis zirconium carbide nanopowder with round shape and crystallite sizes smaller than 20 nm at low temperatures. Also according to thermodynamic calculations, it was concluded that by applying vacuum condition, the zirconium carbide formation can occur at less than 1000°C which is very effective on the size reducing of produced ZrC nanopowders.

New insensitive high-energy dense biopolymers from giant reed cellulosic fibers: synthesis, characterization, and non-isothermal decomposition kinetics

2021 ◽  
Author(s):  
Ahmed Fouzi Tarchoun ◽  
Djalal Trache ◽  
Thomas M. Klapoetke ◽  
Aimen Selmani ◽  
Mohamed Saada ◽  
...  
Keyword(s):  
High Energy ◽  
Decomposition Kinetics ◽  
Giant Reed ◽  
Isothermal Decomposition ◽  
Cellulosic Fibers

The aim of this research was the valorization of giant reed as an alternative bioresource material to produce new promising energetic biopolymers based on carbamated and nitrated ordinary cellulose and...

Silicon carbide formation by methane plasma immersion ion implantation into silicon

2003 ◽  
Vol 21 (4) ◽  
pp. 1375 ◽  
Author(s):  
Zhenghua An ◽  
Ricky K. Y. Fu ◽  
Peng Chen ◽  
Weili Liu ◽  
Paul K. Chu ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Ion Implantation ◽  
Carbide Formation ◽  
Plasma Immersion Ion Implantation
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