Technical Report No.57 (2014)
Shinagawa Technical Report
Director & Managing Executive Officer Ryoichi YOSHINO
From Tap Hole Mud to MgO-C Bricks: The History of a Successful 23-Year Partnership between Saint-Gobain Ceramics and Shinagawa Refractories
Eric SAKO, Douglas GALESI, Vladnilson RAMOS, Marcos FADEL,
Carlos LEÃO,Toshio HORIUCHI and Osamu NOMURA
Due to an increasing demand for high performance refractories from Brazilian market in the 80＇s, Saint-Gobain Ceramics and Shinagawa Refractories decided in 1990 to start a partnership that lasts more than twenty years and has proved its success year by year. From an improved tap hole mud technology to high-quality MgO-C bricks, Shinagawa and Saint-Gobain developed a strong brand in Brazil, contemplating what it takes to grow even more in the promising coming future.
Microstructural Deterioration of Alumina-carbon Refractories for Sliding Gate Plates due to Reactions with Molten Steel
Wei LIN, Fumihiko MIZOBUCHI, Naohide HAMAMOTO and Koji MORIWAKI
Laboratory experiments where alumina-carbon refractories for the sliding plates were immersed into three kinds of molten steel, i.e., ultralow carbon aluminum-killed steel, low carbon aluminumkilled steel and ultralow carbon silicon-killed steel, were carried out in this study. An alumina layer was formed on the surface of the refractory immersed part and a deteriorated zone in which the preexisted carbon and a part of alumina particles had disappeared appeared in the inside of the alumina surface layer in all cases of the steel grades. The mechanism is considered to be that alumina reacts with carbon to produce gases such as Al︵g︶ and CO in the refractories and then these gases form the alumina at the refractory-molten steel interface. The deteriorated zone was the deepest in the case of ultralow carbon aluminum-killed steel. This should be because this steel grade has a low carbon activity, which causes a strong driving force for the reactions between alumina and carbon in the refractories, and the denseness of the alumina surface layer is low, which is unable to prevent the gases diffusion into the molten steel.
Improved Coating Adhesion Test Method for Rotary Cement Kilns
Koichi IGABO, Masahiro KOGA, Kazuhiro INOUE and Masanori OGATA
In rotary cement kilns, the performance of refractory bricks depends largely on the formation of a cement coating on the hot face. A coating adhesion test was conducted by using a rotary slag testing apparatus with an automatic slag feeder and drainer. As a result, the coated specimens with a similar texture to actually used bricks were experimentally reproduced. Microstructure observation revealed that spinel grains of magnesia-spinel brick easily react with cement clinkers to form liquid phase, which infiltrates into the brick matrix to enhance coating adhesion through an anchor effect. However, infiltration of excess amount of liquid phase, derived from not only the spinel decomposition but also partial melting of cement clinker, can cause brick erosion at high temperature.
Examination to Evaluate Corrosion Resistance of Trough Castables for Blast Furnace
Kazuya NAKABO, Kosuke YASUO, Takashi IIDA and Masatsugu KITAMURA
Alumina-silicon carbide-carbon castable refractories are commonly used for the slag line of blast furnace main troughs, and nonoxide raw materials such as silicon carbide and carbon greatly contribute to durability improvement. However, these nonoxide materials are easily affected by oxidation. So, there is a possibility that the castable refractories will not demonstrate the estimated performance in an oxidizing atmosphere. Therefore in this study, we performed corrosion tests under various oxidizing conditions in order to evaluate the effect of oxidation and found out the proper method for estimating the corrosion resistance of materials. The results of the test performed under electric arc heating conditions of which oxidation influence is the least showed the same tendency with the actual use result. This result indicates that the influence of gas phase oxidation in actual use is little, and the corrosion test with electric arc heating is suitable for evaluating the durability of refractories for the slag line of the main trough.
Evaluation Method for Corrosion Resistance of ZrO2-C Material Used at SEN Slag Line
Hiroyasu NIITSUMA, Koji MORIWAKI and Wei LIN
The corrosion resistance of ZrO2 -C material used for the powder line of submerged entry nozzles (SEN) was evaluated by high frequency induction furnace method using molten steel and powder slag. However, some phenomena which never occur in steel continuous casting operation made it difficult to evaluate the refractory corrosion resistance with accuracy. For instance, the oxygen concentration of molten steel tends to increase, which causes the oxidation of steel components, followed by changes in powder slag composition during the test. In this work, we investigated influences of several test conditions and found that the evaluation method using pig iron instead of steel is suitable.
Method for Quantitative Analysis of Free Carbon in Boron Carbide Raw Materials
Katsushige IKEGAMI, Seiji NOBUHARA and Shigeki UCHIDA
When the purity of boron carbide raw materials is determined, it is important to quantitatively analyze the free carbon impurity. The method of wet chemical oxidation and coulometric analysis for the determination of the free carbon is provided in JIS R 2015 (Japanese Industrial Standards). In this study, it was found that the quantitative analysis could be performed approximately according to the JIS. However, the JIS has some problems about the accuracy of analysis. These problems were improved by the following countermeasures. : Selecting the optimum temperature during the wet chemical oxidation process, although it is different from that specified in JIS. Changing the CO and CO2 gas generated in the process to all CO2 by a small improvement in the apparatus. Selecting the optimum particle size of the samples in order to control the wet chemical oxidation speed of boron carbide to obtain a constant speed. Using the appropriate device and procedures with other improvements.
Technical Information on Products
Optimizing Taphole Clay Technology
Taphole clays, which are necessary for blast furnace operation, are one of the key products in our company. There is a large variety of taphole clay. The features of some typical examples from a large number of our products and a part of our activity in research and development for continued improvement of taphole clays will be introduced here.
Mortar for Silica Brick Lining
MK-95D-7：Satisfying DIN Requirement, MK-95D-8：Low Thermal Expansion
Kazuki SAKAWA and Natsumi HIGASHIKAWA
MK︲95D︲7 and MK︲95D︲8 are introduced in this report as silica mortars for silica brick lining. Both mortars exhibit good workability with excellent spreadability. MK︲95D︲7 completely satisfies DIN 1089 Part 3, which defines the specifications for mortar used in coke ovens. Although MK︲95D︲8 contains a larger amount of foreign oxides than specified in DIN specifications, it shows smaller thermal expansion. Thanks to this desirable characteristic, MK︲95D︲8 is suitable for short heating up schedule construction.
Large Size Jointless Monoblock Refractory Lining for Throat Area of RH Degassers…
Noritaka HASHIMOTO and Toshiaki NISHIKADO
A newly developed large size jointless monoblock refractory lining for the throat of RH degassers was investigated. This new technology eliminates red hot temperature on the outer shell surface, which is caused by steel penetration into the joint. Thus, the large size jointless monoblock throat allows to operate stably.
Excellent Al2O3-SiO2 Bricks in Abrasion Resistance
Koichiro MORI and Hirohumi MASUI
Various Al2O3-SiO2 bricks which are excellent in strength and abrasion resistance have been developed by adjusting manufacturing parameters such as raw material composition, molding and sintering. These bricks can be used not only for industrial furnaces which were the original target but also other various applications. We will introduce the features and some application examples of these bricks.
C-SiC Bricks for Industrial Furnaces Operating under Reducing Atmosphere
Hisashi TOMIYA, Masanori OGATA and Koichiro MORI
Although MgO-C bricks are widely used in the electric arc furnace for steelmaking, submerged arc furnaces (SAF) for ferroalloy-making are generally lined with carbon blocks. In the case of electric resistance furnaces (ERF) for ash-melting, which are based on SAF technology, C-SiC bricks are used. Because both SAF and ERF continuously operate under a reducing atmosphere, non-oxide refractories (carbon blocks, C-SiC bricks) perform well without oxidation. C-SiC bricks are characterized by high corrosion resistance to slag and high thermal conductivity. In addition, C-SiC bricks have better oxidation resistance than carbon blocks. C-SiC bricks can be substituted for carbon blocks in various types of industrial furnaces operating under a reducing atmosphere.
Refractory for Aluminum Alloy Melting Furnace Inductor
Moe KITANAKA and Makoto NAMBA
We have developed an SiC inductor block that has excellent thermal spalling resistance called CST︲S530. The developed product has better volume stability than the conventional one and the modulus of elasticity was greatly decreased. We expect a significant long service life and stable durability by applying CST-S530 to the inductor block for the aluminum alloy melting furnace.
Information on Products of Associated Companies
Shinagawa Refractories Australasia Pty. Ltd.
“New Generation Shotcrete Material for Alkali Rich Areas of The Australian Market”
Nathan LEICHT and Mark HERRING
In the Australian refractory market, the main users of shotcrete materials are in the industrial (non steel) markets, particularly the cement and lime industry where resistance to alkali attack is required. Shinagawa Refractories Australasia has developed the NOVACRETEⓇ range of shotcrete products with a focus on excellent installation characteristics across the range while maintaining the application specific formulations required in alkali rich environments.
Shinagawa Fine Ceramics Co., Ltd.
“Characterization and Application of Electrically-conductive α-SiAlON Ceramics”
Atsushi MAKIYA, Masahiro YOSHIKAWA and Kimiaki SASAKI
Electrically-conductive α︲SiAlON ceramics are sintered bodies of α︲SiAlON in which electrical conductive titanium nitride (TiN) particles are finely dispersed. In addition, this ceramics show excellent durability for abrasion due to their high strength and hardness. Recently, the applications of these ceramics have increased mainly for devices which require the removal of electrostatic charge.
Isolite Insulating Products Co., Ltd.
“High Quality Ceramic Fiber Board and Bio Soluble Fiber Product”…
Koji NAKASHIMA and Rokuro MAEDA
Isolite has developed the new high quality ceramic fiber board products ISOWOOL 1260 SI︲BOARD and ISOWOOL BSSR which is made of inorganic bio soluble fiber. SI︲BOARD is 40% better in heat insulation than conventional ISOWOOL 1260 BOARD and is used as heat insulation in industrial heaters to reduce fuel consumption. Because its strength against rupture is twice that of the conventional one, it can be handled more easily. BSSR shows sufficient properties satisfying the standards of bio soluble fiber, thus it is used not only as a substitute for ceramic fiber but as a fire protection material and for heat insulation of home appliances.