scholarly journals Evolution of physicochemical properties of quick lime at converter-smelting temperature

2021 ◽  
Vol 40 (1) ◽  
pp. 32-39
Author(s):  
Mengxu Zhang ◽  
Jianli Li ◽  
Zhengliang Xue ◽  
Renlin Zhu ◽  
Qiqiang Mou ◽  
...  
Keyword(s):  
Boundary Migration ◽  
Average Diameter ◽  
Dissolution Behavior ◽  
Grain Boundary Migration ◽  
Average Pore ◽  
Quick Lime ◽  
Volume Stability ◽  
Steel Making ◽  
Dissolution Efficiency ◽  
Lime Reactivity

Abstract The volume stability caused by the hydration of f-CaO is one of the main obstacles to the comprehensive utilization of steel-making slag. In view of the f-CaO produced by incomplete dissolution of lime, it is necessary to strengthen the dissolution behavior of lime in the converter process. The reactivity of lime determines the dissolution efficiency and is closely related to its microstructure. The experimental results show that the reactivity and porosity of quick lime decrease and the average diameter of pore increases with an increase in temperature. The CaO crystals gradually grow up under the action of grain boundary migration. When the temperature increased from 1,350 to 1,600°C, the lime reactivity decreased from 237.60 to 40.60 mL, the porosity decreased from 30.55 to 15.91%, the average pore diameter increased from 159.10 to 1471.80 nm, and the average CaO particle size increased from 0.33 to 9.61 µm. The results indicate that reactivity is decreased because of the deformation and growth of CaO crystals and the decrease in porosity in reactive lime. This will cause an obstacle to the dissolution of lime and is not conducive to the control of f-CaO in slag.

An Electro-Optical X-Ray Diffraction System for Grain Boundary Migration Measurements at Temperature

1971 ◽  
Vol 15 ◽  
pp. 435-445
Author(s):  
Robert E. Green
Keyword(s):  
Grain Boundary ◽  
Test Specimen ◽  
Boundary Migration ◽  
Aluminum Foil ◽  
Average Diameter ◽  
Absolute Measurement ◽  
Grain Boundary Migration ◽  
X Ray ◽  
Cold Worked ◽  
Considerable Work

Considerable work has been undertaken in order to gain an understanding of the mechanisms responsible for the generation of recrystallization textures developed upon annealing of cold-worked metals. Most direct measurements have consisted of measuring the increase in average diameter of the largest grain growing into a polycrystalline aggregate. Experimental measurements of individual boundaries migrating into deformed single crystals, though of a more fundamental nature, have been made by far fewer investigators. This is probably due to the increased experimental difficulties associated with careful control of such experiments. Most previous investigators have made grain boundary migration measurements by the heat-cool-etch method, despite the fact that it has several marked disadvantages. Other investigators have constructed an X-ray goniometer furnace and used it to measure grain boundary migration rates while the test specimen was maintained at temperature. Since there have been no published reports of the use of such a system in the past thirteen years, it must be concluded that the technique was unsuccessful in general.The system described in the present work is relatively simple in design and extremely simple to use. Not only does it permit absolute measurement of grain boundary position at temperature but it also permits boundary migration measurements to be made of extremely fast moving boundaries. The basic components of the system are as follows. A continuous spectrum X-ray beam is converted by a slit collimating system into a beam which is incident along the entire length of the test specimen. This beam is interrupted by a wire grid just prior to impingement on the test specimen. The test specimen is supported vertically in a furnace maintained at the temperature required for grain boundary migration. The various diffracted X-ray beams pass out of the furnace through a highly reflecting insulating baffle made from very thin aluminum foil and impinge on a fluorescent screen. This screen converts the X-ray image into a visible one which is amplified and recorded using the electro-optical system.

Measurement of solute segregation to grain boundaries in the AEM: A review

1988 ◽  
Vol 46 ◽  
pp. 606-607
Author(s):  
D. B. Williams ◽  
A. D. Romig
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Boundary Misorientation ◽  
Collector Plate ◽  
Segregation Process ◽  
Grain Boundary Misorientation ◽  
Structure Boundary ◽  
Equilibrium Segregation

The segregation of solute or imparity elements to grain boundaries can occur by three well-defined processes. The first is Gibbsian segregation in which an element of minimal matrix solubility confines itself to a monolayer at the grain boundary. Classical examples include Bi in Cu and S or P in Fe. The second process involves the depletion of excess matrix solute by volume diffusion to the boundary. In the boundary, the solute atoms diffuse rapidly to precipitates, causing them to grow by the ‘collector-plate mechanism.’ Such grain boundary diffusion is thought to initiate “Diffusion-Induced Grain Boundary Migration,” (DIGM). This process has been proposed as the origin of eutectoid transformations or discontinuous grain boundary reactions. The third segregation process is non-equilibrium segregation which result in a solute build-up around the boundary because of solute-vacancy interactions.All of these segregation phenomena usually occur on a sub-micron scale and are often affected by the nature of the grain boundary (misorientation, defect structure, boundary plane).

Domain coarsening by grain boundary migration in ordered Ni4Mo

1986 ◽  
Vol 44 ◽  
pp. 560-561
Author(s):  
K. Vasudevan ◽  
H. P. Kao ◽  
C. R. Brooks ◽  
E. E. Stansbury
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Short Range ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Rapid Cooling ◽  
Temperature Range ◽  
Fee Structure ◽  
Domain Coarsening ◽  
Boundary Reaction

The Ni4Mo alloy has a short-range ordered fee structure (α) above 868°C, but transforms below this temperature to an ordered bet structure (β) by rearrangement of atoms on the fee lattice. The disordered α, retained by rapid cooling, can be ordered by appropriate aging below 868°C. Initially, very fine β domains in six different but crystallographically related variants form and grow in size on further aging. However, in the temperature range 600-775°C, a coarsening reaction begins at the former α grain boundaries and the alloy also coarsens by this mechanism. The purpose of this paper is to report on TEM observations showing the characteristics of this grain boundary reaction.

STUDY OF THE GRAIN BOUNDARY MIGRATION IN A TRICRISTAL PURE ICE WITH BUBBLES

Anales AFA ◽  
2019 ◽  
Vol 30 (3) ◽  
pp. 47-51
Author(s):  
P.I. Achával ◽  
C. L. Di Prinzio
Keyword(s):  
Monte Carlo ◽  
Grain Boundary ◽  
Numerical Simulations ◽  
Triple Junction ◽  
Boundary Migration ◽  
Optical Microscope ◽  
Physical Parameters ◽  
Grain Boundary Migration

In this paper the migration of a grain triple junction in apure ice sample with bubbles at -5°C was studied for almost 3hs. This allowed tracking the progress of the Grain Boundary (BG) and its interaction with the bubbles. The evolution of the grain triple junction was recorded from successive photographs obtained witha LEICA® optical microscope. Simultaneously, numerical simulations were carried out using Monte Carlo to obtain some physical parameters characteristic of the BG migration on ice.

Effect of grain boundary migration on intergranular fracture in the weld metal of steels

2021 ◽  
pp. 1-9
Author(s):  
Suo Saruwatari ◽  
Takahiro Kamo ◽  
Yuki Nakata ◽  
Kota Kadoi ◽  
Hiroshige Inoue
Keyword(s):  
Grain Boundary ◽  
Weld Metal ◽  
Intergranular Fracture ◽  
Boundary Migration ◽  
Grain Boundary Migration

Increased Thermal Stability of Co-silicide Using Co-Ta Alloy Films

2001 ◽  
Vol 670 ◽  
Author(s):  
Min-Joo Kim ◽  
Hyo-Jick Choi ◽  
Dae-Hong Ko ◽  
Ja-Hum Ku ◽  
Siyoung Choi ◽  
...  
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Grain Boundary ◽  
Reaction Rate ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Alloy Films ◽  
Post Annealing ◽  
Alloy Process ◽  
Thermal Stability Of

ABSTRACTThe silicidation reactions and thermal stability of Co silicide formed from Co-Ta/Si systems have been investigated. In case of Co-Ta alloy process, the formation of low resistive CoSi2phase is delayed to about 660°C, as compared to conventional Co/Si system. Moreover, the presence of Ta in Co-Ta alloy films reduces the silicidation reaction rate, resulting in the strong preferential orientation in CoSi2 films. Upon high temperature post annealing in the furnace, the sheet resistance of Co-silicide formed from Co/Si systems increases significantly, while that of Co-Ta/Si systems maintains low. This is due to the formation of TaSi2 at the grain boundaries and surface of Co-silicide films, which prevents the grain boundary migration thereby slowing the agglomeration. Therefore, from our research, increased thermal stability of Co-silicide films was successfully obtained from Co-Ta alloy process.

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