Effect of Dense Layer Formation on Dissolution Rate of MgO-C Refractory in Molten Slag

2006 ◽  
Vol 45 ◽  
pp. 162-166 ◽  
Author(s):  
Hiroyuki Sunayama ◽  
Masayasu Kawahara
Keyword(s):  
Chemical Composition ◽  
Corrosion Rate ◽  
Corrosion Test ◽  
Molten Slag ◽  
Cylindrical Specimen ◽  
Rotating Cylinder ◽  
Dense Layer ◽  
Layer Formation ◽  
The Matrix ◽  
Cylinder Method

The corrosion test for magnesia-carbon refractory, MgO-C, with dense layer has been carried out by a rotating cylinder method at 1673 K. The specimen, which was a cylinder of 25 mm diameter and 25mm height, was rotated in molten slag at 50 rpm. The chemical composition of slag was CaO-SiO2-FeO-MgO-CaF2. The corrosion rate was determined by the variation of radius of the cylindrical specimen against corrosion time. The decrease of radius was obtained by a calculation of dissolved MgO into the slag. In addition, the diameter of the specimen was measured with a slide calipers after the corrosion test. The cylindrical specimen was heated to form a dense layer before the corrosion test. The corrosion rate of the MgO-C refractory with dense layer was slower than that of the MgO-C refractory without dense layer. The oxidized layer, where the dense layer formed, dissolved at much the same rate as the MgO brick. The dense layer probably obstructed contact between slag and carbon in the matrix, and then oxidation of C by slag did not take place. Formation of the dense layer was effective to inhibit corrosion of MgO-C refractory by molten slag.

Corrosion behaviour and corrosion mechanism of corundum block and mullite block in hearth of blast furnace

2021 ◽  
Vol 118 (5) ◽  
pp. 511
Author(s):  
Shun Yao ◽  
Heng Zhou ◽  
Shengli Wu ◽  
Bo Song ◽  
Mingyin Kou
Keyword(s):  
Corrosion Resistance ◽  
Blast Furnace ◽  
High Temperature ◽  
Corrosion Rate ◽  
Molten Slag ◽  
Molten Iron ◽  
Transport Rate ◽  
Diffusive Transport ◽  
The Matrix ◽  
Corrosion Mechanisms

A ceramic cup is often used to prolong the hearth life of a blast furnace (BF). Corundum blocks and mullite blocks are two kinds of refractories widely used for building ceramic cups in China. Therefore, research on the corrosion resistance of these two kinds of refractories is beneficial to realize the BF longevity. In this study, the corrosion behaviours and corrosion mechanisms of molten slag and molten iron on corundum block and mullite block samples were investigated by corrosion tests. The results show that the slag corrosion resistance of corundum block was better than that of mullite block, and the corrosion mechanisms of molten slag on corundum block and mullite block were different. The aggregates fell from the matrix of the corundum sample when the matrix was corroded to a certain degree by slag, and the corrosion rate of slag on the corundum sample was controlled by the diffusive transport rate of a substance and the chemical reaction rate between slag and matrix. However, the aggregate and matrix of the mullite sample was corroded by slag at the same time, and the corrosion rate of slag on the mullite sample was controlled by the diffusive transport rate of Ca through the newly formed reaction layer. Moreover, the corundum block and mullite block had excellent iron corrosion resistance. The high temperature of molten iron led to an in situ reaction to generate a mullite phase in the corundum sample, and the high temperature affected the microstructure of the corundum block and mullite block.

scholarly journals Corrosion Behavior of Copper Bearing Steels and the Derived In-Situ Coating

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1462
Author(s):  
Na Li ◽  
Ling Yan ◽  
Shaodong Wang ◽  
Changshun Wang ◽  
Hongmei Zhang ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Copper Content ◽  
Corrosion Test ◽  
Electrochemical Corrosion ◽  
Rust Layer ◽  
Two Phase ◽  
Corrosion Condition ◽  
Bearing Steels ◽  
The Matrix

Using a period immersion wet/dry cyclic corrosion test, in-situ copper-coated steels prepared by corroding copper-bearing steels were investigated in this study. The steel with a higher copper content (>3%) has a higher initial corrosion rate due to its obvious two-phase microstructure. The corrosion rates of all copper bearing steels tend to be stable after a certain time of corrosion. A copper-rich layer is formed between the matrix and the rust layer, which is due to the diffusion of copper from the rust layer to the metal surface. The copper’s stability under this corrosion condition led to the formation of a thin copper-rich film, which was uncovered after removing the rust by choosing appropriate descaling reagents. The copper coating was generated from the matrix itself during the corrosion process at 25 °C, which provided a new approach for producing in-situ composite materials without any bonding defect. It is found that the corrosion rate, corrosion time, and copper content in steel all affect the formation of copper-rich layer. In addition to the noble copper surface, the electrochemical corrosion test results show that the corrosion resistance of copper-coated steel has been significantly improved.

Structural/Property Relationships for Optical Materials

1993 ◽  
Vol 329 ◽  
Author(s):  
Vivien D.
Keyword(s):  
Crystal Structure ◽  
Optical Properties ◽  
Electronic Structure ◽  
Chemical Composition ◽  
Field Strength ◽  
Optical Materials ◽  
Site Occupancy ◽  
Laser Materials ◽  
Crystal Field Strength ◽  
The Matrix

AbstractIn this paper the relationships between the crystal structure, chemical composition and electronic structure of laser materials, and their optical properties are discussed. A brief description is given of the different laser activators and of the influence of the matrix on laser characteristics in terms of crystal field strength, symmetry, covalency and phonon frequencies. The last part of the paper lays emphasis on the means to optimize the matrix-activator properties such as control of the oxidation state and site occupancy of the activator and influence of its concentration.

Viscosity Evaluation of Multi-phases Flux by Rotating Cylinder Method

2009 ◽  
Vol 95 (12) ◽  
pp. 807-812 ◽  
Author(s):  
Sohei Sukenaga ◽  
Shinichiro Haruki ◽  
Yoshinori Yamaoka ◽  
Noritaka Saito ◽  
Kunihiko Nakashima
Keyword(s):  
Rotating Cylinder ◽  
Cylinder Method

scholarly journals Superhydrophobicity in perfection: the outstanding properties of the lotus leaf

2011 ◽  
Vol 2 ◽  
pp. 152-161 ◽  
Author(s):  
Hans J Ensikat ◽  
Petra Ditsche-Kuru ◽  
Christoph Neinhuis ◽  
Wilhelm Barthlott
Keyword(s):  
Chemical Composition ◽  
Water Repellency ◽  
Contact Angles ◽  
Dense Layer ◽  
Lotus Effect ◽  
Nano Structure ◽  
Lotus Leaf ◽  
Water Drops ◽  
The Impact ◽  
Unique Chemical

Lotus leaves have become an icon for superhydrophobicity and self-cleaning surfaces, and have led to the concept of the ‘Lotus effect’. Although many other plants have superhydrophobic surfaces with almost similar contact angles, the lotus shows better stability and perfection of its water repellency. Here, we compare the relevant properties such as the micro- and nano-structure, the chemical composition of the waxes and the mechanical properties of lotus with its competitors. It soon becomes obvious that the upper epidermis of the lotus leaf has developed some unrivaled optimizations. The extraordinary shape and the density of the papillae are the basis for the extremely reduced contact area between surface and water drops. The exceptional dense layer of very small epicuticular wax tubules is a result of their unique chemical composition. The mechanical robustness of the papillae and the wax tubules reduce damage and are the basis for the perfection and durability of the water repellency. A reason for the optimization, particularly of the upper side of the lotus leaf, can be deduced from the fact that the stomata are located in the upper epidermis. Here, the impact of rain and contamination is higher than on the lower epidermis. The lotus plant has successfully developed an excellent protection for this delicate epistomatic surface of its leaves.

scholarly journals VIII.—Analysis of a Spherulite and the Matrix in a Natural and an Artificial Rock

1896 ◽  
Vol 3 (8) ◽  
pp. 365-371
Author(s):  
H. H. F. Hyndman ◽  
T. G. Bonney
Keyword(s):  
Chemical Composition ◽  
Distinct Difference ◽  
Artificial Rock ◽  
The Matrix ◽  
Basic Rocks

The differences in chemical composition between spherulites and the matrices which contain them have been determined by many analysts. Michel Lévy, in a long and comprehensive paper, quotes some former analyses by Delesse, comparing them with his own, which they closely resembled. Lagario gives many analyses which are especially valuable, as he compares results from acid with those from intermediate and basic rocks, and finds a distinct difference between them. The relations of these results will be briefly considered at the end of the present paper.

Effect of nickel content in the corrosion process of TiC/Cu-Ni composites immersed in synthetic seawater

MRS Advances ◽  
2019 ◽  
Vol 4 (63) ◽  
pp. 3475-3484
Author(s):  
Miguel A. Téllez-Villaseñor ◽  
Carlos A. León Patino ◽  
Ricardo Galván Martínez ◽  
Ena A. Aguilar Reyes
Keyword(s):  
Corrosion Rate ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Nickel Content ◽  
Corrosion Mechanism ◽  
Composite Surface ◽  
Synthetic Seawater ◽  
Ni Content ◽  
The Matrix ◽  
Static Conditions

ABSTRACTThe work presents an electrochemical study of the corrosion behaviour of two TiC/Cu-Ni metal matrix composites with a content of 10 and 20 wt.% Ni immersed in synthetic seawater. The composites were synthesized by a capillary infiltration technique, obtaining dense materials TiC/Cu-10Ni and TiC/Cu-20 Ni with a residual porosity of 1.8 and 1.7%, respectively. The corrosion rate (CR) was evaluated from the techniques of polarization curves (PC), linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS). Electrochemical measurements were carried out under static conditions, ambient temperature and atmospheric pressure at 24 hours exposure in the electrolytic medium. The corrosion rate is affected by the Ni content in the matrix, with less corrosion in the composite with a higher Ni content. The higher content of Ni in the Cu-Ni alloy provides higher passivation and stability to the corrosion products film that are absorbed on the composite surface. Microscopic examination (SEM) showed a characteristic morphology of a corrosion mechanism of the localized type (pits and crevices) generated by a differential aeration, where the TiC/Cu-10Ni composite showed greater degradation.

Study on the Crack Forming during Cold Forging Process of ML25Mn Steel

2012 ◽  
Vol 184-185 ◽  
pp. 1255-1258
Author(s):  
Zhuang Li ◽  
Di Wu ◽  
Wei Lv
Keyword(s):  
Chemical Composition ◽  
Surface Quality ◽  
High Hardness ◽  
Complex Oxides ◽  
Cold Forging ◽  
Internal Defects ◽  
Forging Process ◽  
Sem Observation ◽  
Metallic Inclusions ◽  
The Matrix

The important factors that affect the formability of the cold forging steel are its surface quality and internal defects. The cracking phenomenon was taken place during cold forging of ML25Mn steel. In this study, microstructural analyses were made on around the cracked regions of the steel. The reason of cracking, which occurred during cold forging for ML25Mn steel, was investigated based on SEM observation in detail. The results have shown that the crack forming during cold forging process is not related to the chemical composition for ML25Mn steel. Cracking is not resulted from high hardness of the steel rods. There are some non-metallic inclusions in the matrix of ML25Mn steel, and the film-like inclusions are composed of MnS, CaS and complex oxides containing Mg, Al, Mn, Fe, S, Ca and O. The formation of non-metallic inclusions is the result of the deoxidation and the solidification during smelting and casting of steel.

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