scholarly journals Study on Upgradation in Carburizing Technologies for steel strength

2019 ◽  
pp. 78-84
Keyword(s):  
Surface Hardness ◽  
Carbon Diffusion ◽  
Lower Surface ◽  
Diffusion Controlled ◽  
Steel Strength ◽  
Carbon Transfer ◽  
Gas Carburizing ◽  
Kinetics Of ◽  
Plasma Carburizing ◽  
Carburizing Process

Carburizing technologies are used to provide strength on low quality metals. This technology is being developing with novel improvements significantly. The carburizing process consists of, first releasing Carbon mono-oxide from charcoal material and then transfers carbon to raw metal. There are favorable upgradation in these technologies from researchers which have a paramount industrial importance. In Vacuum gas carburizing, the steel metal is carburized with (Acetylene and Propane) gases. These gases are at low pressure and high temperature. The results show that the metal is 1.5 times harder than its raw form. There are also used mathematical models to validate the results. It used gas and solid phases for validation. In pulse carburizing, carbon diffusion on steel is investigated with heat treatment. This process includes several carburizing stages. This process is based on Darken bi velocity and drift velocity. It accounts to demonstrate the kinetics of carbon transfer on steel surface. This design is very useful by regarding carburizing time for this process design. In Plasma carburizing, the mixtures of gases are used to harden the steel. The carburizing temperature was varied in cementite and martensitic. The favorable results show that these specimens have (Lower surface roughness, higher surface hardness and Low wear rate). It is a most novel diffusion controlled novel process till the present time. The carburized metal is used in industry by including (Turbine gears and Air craft engine). Henceforth, It is of great importance to study the carburizing technologies for providing better strength on metal.

Pulse Carburization of Steel – Model of the Process

2014 ◽  
Vol 354 ◽  
pp. 145-152 ◽  
Author(s):  
M. Zajusz ◽  
K. Tkacz-Śmiech ◽  
K. Dychtoń ◽  
Marek Danielewski
Keyword(s):  
Potential Gradient ◽  
Computer Experiments ◽  
Carbon Diffusion ◽  
Diffusion In Solids ◽  
Treatment Conditions ◽  
Carbon Transfer ◽  
Gas Carburizing ◽  
Kinetics Of ◽  
And Diffusion ◽  
Carburizing Process

Gas carburizing is a widely used heat treatment process in which carbon is transferred into steel. The hardening reliability involves an active control of mass transfer during the process and this is why understanding diffusion in solids is so essential to model the process. The currently used models are often based on the simplest, one-dimensional form of the diffusion equation in which diffusivity depends on composition. The objective of this work is to develop a model of carbon diffusion in multicomponent alloy subjected to pulse carburizing. The model is based on the Darken method (bi-velocity method) in which the diffusion velocity depends on the diffusion potential gradient and is independent of the choice of the reference frame while the drift velocity is common for the carbon and steel components. Our model allows predicting the kinetics of carbon transfer at various treatment conditions and is applied to the pulse carburizing process at constant temperature. The process is carried out by repeating consecutively a carburization stage, when the carburizing gas is supplied into a carburizing chamber, and a diffusion stage at vacuum conditions, when the carburizing gas is exhausted and only the diffusion of carbon takes place. The numerical calculations are made for varying carburization and diffusion periods and are confirmed by the experimental results. On the basis of the series of computer experiments some findings that are important in designing the carburizing technology are formulated.

A Study on Properties and Kinetics of Carburizing Superplastic Duplex Stainless Steel

2006 ◽  
Vol 326-328 ◽  
pp. 1677-1680 ◽  
Author(s):  
Nik Rozlin Nik Masdek ◽  
Iswadi Jauhari ◽  
Raden Dadan Ramdan ◽  
Rafidah Hasan
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Carbon Diffusion ◽  
Carbon Layer ◽  
Case Depth ◽  
Hard Carbon ◽  
Metallographic Technique ◽  
New Type ◽  
Kinetics Of ◽  
Carburizing Process

In this study, a new type of surface carburizing process was introduced using superplastic duplex stainless steel (DSS). The superplastic DSS was carburized at temperatures ranging from 1123 K to 1223 K for various durations. Initial pressures of 25 MPa, 49 MPa and 74 MPa were applied to give the superplastic deformation effect on the carburized specimens. SEM studies revealed a thick, uniform, smooth and dense hard carbon layer was formed on the surface of the superplastic DSS. By using metallographic technique and SEM, the resulting case depth of carbon layer was between 15 /m to 76 /m. The kinetics of this process in terms of carbon diffusion and its variation with processing time and temperature was determined using Arrhenius equation. Activation energy (Q) was determined as 152 kJ/mol.

Enhancing Surface Properties of Fine Grain Duplex Stainless Steel via Superplastic Carburizing

2006 ◽  
Vol 15-17 ◽  
pp. 768-773 ◽  
Author(s):  
Nik Rozlin Nik Masdek ◽  
Iswadi Jauhari ◽  
Hiroyuki Ogiyama ◽  
Rafidah Hasan
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Surface Properties ◽  
Surface Hardness ◽  
Carbon Diffusion ◽  
Carbon Layer ◽  
Case Depth ◽  
Fine Grain ◽  
New Type ◽  
Kinetics Of

In this research, a new type of surface carburizing method which combines superplastic phenomenon and carburizing process called superplastic carburizing (SPC) was introduced. Thermo-mechanically treated duplex stainless steel (DSS) with fine grain microstructure and exhibits superplasticity was used as the superplastic material. The SPC was conducted at temperatures ranging from 1123 K to 1223 K for various durations. Initial loads of 25 MPa, 49 MPa and 74 MPa were applied to give the superplastic deformation effect on the carburized specimens. Metallographic studies revealed a thick, uniform, smooth and dense morphology of hard carbon layer formed at the surface of fine grain DSS. The resulting case depth of carbon layers were between 15 μm to 76 μm. A remarkable increase in surface hardness was observed in the range of 600 HV to 1600 HV. The kinetics of this process in terms of carbon diffusion and its variation with processing time and temperature was achieved using Arrhenius equation. Activation energy (Q) was determined as 151.87 kJ/mol. Based on the results obtained, SPC process can significantly enhance the surface properties of DSS.

scholarly journals Synthesis and Polymerization Kinetics of Rigid Tricyanate Ester

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1686
Author(s):  
Andrey Galukhin ◽  
Roman Nosov ◽  
Ilya Nikolaev ◽  
Elena Melnikova ◽  
Daut Islamov ◽  
...  
Keyword(s):  
Kinetic Analysis ◽  
Single Step ◽  
Polymerization Kinetics ◽  
Scanning Calorimetry ◽  
Modulated Differential Scanning Calorimetry ◽  
Diffusion Controlled ◽  
Polymerization Product ◽  
The One ◽  
Kinetics Of

A new rigid tricyanate ester consisting of seven conjugated aromatic units is synthesized, and its structure is confirmed by X-ray analysis. This ester undergoes thermally stimulated polymerization in a liquid state. Conventional and temperature-modulated differential scanning calorimetry techniques are employed to study the polymerization kinetics. A transition of polymerization from a kinetic- to a diffusion-controlled regime is detected. Kinetic analysis is performed by combining isoconversional and model-based computations. It demonstrates that polymerization in the kinetically controlled regime of the present monomer can be described as a quasi-single-step, auto-catalytic, process. The diffusion contribution is parameterized by the Fournier model. Kinetic analysis is complemented by characterization of thermal properties of the corresponding polymerization product by means of thermogravimetric and thermomechanical analyses. Overall, the obtained experimental results are consistent with our hypothesis about the relation between the rigidity and functionality of the cyanate ester monomer, on the one hand, and its reactivity and glass transition temperature of the corresponding polymer, on the other hand.

Primary products and processes in the γ-radiolysis of 2-methyltetrahydrofuran

1965 ◽  
Vol 285 (1402) ◽  
pp. 319-338 ◽  
Keyword(s):  
Glassy Phase ◽  
Kcal Mole ◽  
Radical Species ◽  
Molecule Reaction ◽  
Positive Ions ◽  
Primary Products ◽  
Diffusion Controlled ◽  
Thermal Bleaching ◽  
The Matrix ◽  
Kinetics Of

From a study of the u. v., visible, near i. r. and e. s. r. spectra induced by γ -irradiation at 77°K in glassy MTHF and in glassy MTHF containing various additives and from a study of controlled temperature increases on these spectra, the following conclusions are drawn. (1) The primary products of the radiolysis are electrons ( e - ) and positive ions ( MTHF + ) which undergo a rapid ion-molecule reaction to give O CH 3 radicals ( R ⋅). (2) e - can either be trapped in the glassy MTHF matrix or can be captured by either napththalene, ferric chloride, carbon tetrachloride, nitrous oxide or trans -stilbene if these substances are present. (3) The e - T are bleachable by light or heat and disappear independently of the radicals R⋅ without either augmentation of R⋅ or the production of any new radical species. (4) e - T and R⋅ disappear thermally and independently by second-order reactions, the rate constants being K e - + e - (M -1 S -1 ) = 10 12⋅4±1⋅1 exp ─ [0⋅85 ± 0⋅10 kcal/mole/ R ( T ─ 75)] and K R˙ + R˙ (M -1 S -1 ) = 10 13⋅3±1⋅4 exp ─ [1⋅20 ± 0⋅15 kcal/mole/ R ( T ─ 75)]. These rate expressions suggest that both reactions are diffusion controlled at low temperatures in the glassy phase. (5) The kinetics of the thermal bleaching of e - T indicate that the electrons migrate distances of about 150 Å from their parent positive ions before being trapped in the matrix. (6) The effect of FeCl 3 in reducing the formation of e - T at 77°K and its lack of effect on the thermal bleaching of e - T suggests that the reaction e - + FeCl 3 → FeCl 2 + Cl - only occurs before the electron is thermalized.

Vacancy-Mediated Diffusion and Diffusion-Controlled Processes in Ordered Binary Intermetallics by Kinetic Monte Carlo Simulations

2021 ◽  
Vol 29 ◽  
pp. 95-115
Author(s):  
Rafal Kozubski ◽  
Graeme E. Murch ◽  
Irina V. Belova
Keyword(s):  
Monte Carlo ◽  
Kinetic Monte Carlo ◽  
Simulation Studies ◽  
Self Diffusion ◽  
Monte Carlo Techniques ◽  
Diffusion Controlled ◽  
Kinetic Monte Carlo Simulations ◽  
Kinetic Effects ◽  
Kinetics Of ◽  
And Diffusion

We review the results of our Monte Carlo simulation studies carried out within the past two decades in the area of atomic-migration-controlled phenomena in intermetallic compounds. The review aims at showing the high potential of Monte Carlo methods in modelling both the equilibrium states of the systems and the kinetics of the running processes. We focus on three particular problems: (i) the atomistic origin of the complexity of the ‘order-order’ relaxations in γ’-Ni3Al; (ii) surface-induced ordering phenomena in γ-FePt and (iii) ‘order—order’ kinetics and self-diffusion in the ‘triple-defect’ β-NiAl. The latter investigation demonstrated how diverse Monte Carlo techniques may be used to model the phenomena where equilibrium thermodynamics interplays and competes with kinetic effects.

Heat Treatment Process and Parameter Design in Manufacturing

2000 ◽  
Author(s):  
Ramana V. Grandhi ◽  
Zhichao Li
Keyword(s):  
Heat Treatment ◽  
Volume Fraction ◽  
Surface Hardness ◽  
Surface Method ◽  
Design Variables ◽  
Element Simulation ◽  
Gas Carburizing ◽  
Quenchant Temperature ◽  
The Heat Transfer Coefficient ◽  
Material Temperature

Abstract The heat treatment operation which is carried out post manufacturing is optimized. Simulation of the carburizing and quenching processes with parameter optimization are combined to attain the desired surface hardness with controlled distortion of final products. Parameters of interest for optimization include, the carbon content of gas, carburizing dwell time, material temperature before quenching, quenchant temperature and the heat transfer coefficient. The response surface method is used to obtain closed-form models of the objective (surface hardness) and the two constraints (hardness variance and physical distortion) in terms of the design variables. A finite element simulation tool is used to predict the material response (volume fraction of different phases, temperature and stress/strain) during the carburizing and quenching processes. This paper summarizes the methodology that is used to optimize the carburizing and quenching processes of an axisymmetric disk.

Effect of Excess PbO on the Kinetics of the Growth of PMNT Polycrystals by Templated Grain Growth Method

2005 ◽  
Vol 475-479 ◽  
pp. 1137-1140
Author(s):  
Lili Zhao ◽  
Feng Gao ◽  
Wei Min Wang ◽  
Chang Sheng Tian
Keyword(s):  
Grain Growth ◽  
Templated Grain Growth ◽  
Experimental Conditions ◽  
Precipitation Mechanism ◽  
Oriented Structure ◽  
Diffusion Controlled ◽  
The Matrix ◽  
Growth Method ◽  
Final Composition ◽  
Kinetics Of

The oriented 0.67Pb (Mg1/3Nb2/3)O3-0.33PbTiO3 (PMNT) polycrystals were prepared by the conventional ceramic technique and the templated grain growth method adding excess PbO in the matrix. Kinetics of the development of oriented structure was investigated systemically. In the presence of PbO liquid phase, the oriented PMNT polycrystals mainly grow by the dissolution-precipitation mechanism. The diffusion is determined by the sintering temperature and the PbO-excess content in the matrix. The thickness of oriented PMNT polycrystals displays a t1/3 dependence, which is characteristic of diffusion-controlled growth. For the thicker oriented structure, 20% excess PbO in the PMNT matrix and 1150oC for 10h are the proper experimental conditions. Moreover, the addition of PbO in the matrix hardly affects the final composition of ceramic matrix.

omparisons of Silicide Formation by Rapid Thermal Annealing and Conventional Furnace Annealing

1987 ◽  
Vol 92 ◽  
Author(s):  
E. Ma ◽  
M. Natan ◽  
B.S. Lim ◽  
M-A. Nicolet
Keyword(s):  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Silicide Formation ◽  
X Ray Diffraction ◽  
Furnace Annealing ◽  
Cross Sectional ◽  
Conventional Furnace ◽  
Diffusion Controlled ◽  
Conventional Furnace Annealing ◽  
Kinetics Of

ABSTRACTSilicide formation induced by rapid thermal annealing (RTA) and conventional furnace annealing (CFA) in bilayers of sequentially deposited films of amorphous silicon and polycrystalline Co or Ni is studied with RBS, X-ray diffraction and TEM. Particular attention is paid to the reliability of the RTA temperature measurements in the study of the growth kinetics of the first interfacial compound, Co2Si and Ni2Si, for both RTA and CFA. It is found that the same diffusion-controlled kinetics applies for the silicide formation by RTA in argon and CFA in vacuum with a common activation energy of 2.1+0.2eV for Co2Si and 1.3+0.2eV for Ni Si. Co and Ni atoms are the dominant diffusing species; during silicide formation by both RTA and CFA. The microstructures of the Ni-silicide formed by the two annealing techniques, however, differs considerably from each other, as revealed by cross-sectional TEM studies.

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