8 Characteristics of Honeycomb Ceramic Catalyst Carrier

The main material of honeycomb ceramic carrier is cordierite. The honeycomb ceramic material used for automobile exhaust treatment is often porous cordierite, which mainly provides an inert physical structure for carrying the catalyst coating. The thermal expansion coefficient of cordierite is 2.9X10-6/℃. The melting point is about 1460℃, and it has good thermal stability. Cordierite has two homogeneous multiphase variants, namely low-temperature cordierite and high-temperature cordierite. High-temperature cordierite is also known as Indialite, which belongs to the hexagonal system; low-temperature cordierite is what people usually call cordierite, which belongs to the orthorhombic system. Rongsheng cordierite honeycomb ceramic manufacturer provides high-quality cordierite honeycomb ceramic products. Contact Rongsheng for detailed information.

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Honeycomb Ceramic Catalyst Carrier

In order to have a larger catalytic surface in a smaller volume, the surface of the catalyst carrier is made into a honeycomb shape. The biggest advantage is that it has a large specific surface, a low thermal expansion coefficient, excellent thermal shock resistance, strong acid and alkali resistance and corrosion resistance, and has high mechanical strength.

As a carrier, honeycomb ceramic is a key component of the three-way catalytic converter. One of its important materials is cordierite, which is resistant to high temperatures, has a high continuous operating temperature of up to 1200°C, high strength and low linear expansion coefficient. The carrier adopts an effective surface and a suitable pore structure. The ceramic carrier has an opening rate of 400-600 mesh/inch2 and a minimum wall thickness of about 0.16mm. It can enhance the mechanical strength of the catalyst, and also improve its resistance to wear, impact, gravity, pressure, high temperature and phase change. Improve the conductivity of the catalyst and reduce the content of active components. Especially when using precious metal catalysts such as platinum, palladium and rhodium, the active components can be highly dispersed and the dosage can be reduced.

In short, the quality of the carrier is extremely important for the catalyst. The mesh number of the honeycomb ceramic carrier can be 200 mesh, 300 mesh, 400 mesh or 600 mesh. The cross-sectional shapes include circular, racetrack, elliptical and some special shapes according to customer requirements, in order to meet the needs of different application conditions.

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Characteristics of Honeycomb Ceramic Catalyst Carrier

Honeycomb ceramic catalyst carrier has eight significant advantages, as follows:

1. Thin pore wall, large specific surface area, low resistance, low bulk density, high compressive strength.
2. Small thermal expansion coefficient.
3. Good thermal shock resistance and thermal shock resistance.
4. Good matching with various catalyst active components.
5. Good cold start performance, low ignition temperature, fast heating, small gas resistance, high conversion efficiency.
6. Spiral, double S and three-core core structures can be produced according to user requirements.
7. It can be designed into cylindrical, runway and other special-shaped structures according to the requirements of different motor vehicles.
8. The product meets the manufacturing and supporting requirements of various scales and models of motor vehicles and meets Euro III and more stringent emission standards.

Application of Cordierite Ceramics

1. Square mirrors for photolithography

As one of the core units of a photolithography machine, the motion accuracy of the ultra-precision worktable directly affects the resolution of the photolithography machine. As the core component of the worktable, the square mirror guarantees the accuracy of the worktable and the efficiency of photolithography. The thermal load on the square mirror during operation will change continuously due to the influence of the heat flow in the working space, requiring its deformation to change as little as possible with temperature. At the same time, it is also necessary to deal with the distortion correction caused by its operation at higher acceleration and speed. Therefore, in order to meet the requirements of photolithography accuracy, the thermal expansion coefficient of the square mirror material must achieve near-zero expansion at the working temperature, and it must also have good mechanical properties. Cordierite ceramics are ideal materials for square mirrors for photolithography machines due to their low thermal expansion coefficient, excellent mechanical properties and low density. ASML has achieved mature application and promotion of cordierite ceramics in the mobile platform components of photolithography machines.

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2. Optical mirrors for optical communication

Cordierite has the characteristics of low thermal expansion, high mechanical strength and high rigidity, long-term dimensional stability, and radiation resistance, and can be used in space optical communication. Sony CSL has adopted Kyocera cordierite ceramic mirrors for small near-Earth orbit security laser communication terminals.

3. Refractory materials

Cordierite ceramics are often used as ceramic packaging materials and kiln tools during the use of kilns due to their low thermal expansion coefficient. At the same time, cordierite ceramics have the characteristics of low density, low thermal conductivity and good high-temperature stability, and can also be used in heat exchange devices with fast temperature changes, such as heat-resistant pots. There are a large number of gaps between the six-membered rings of cordierite crystals and between the upper and lower adjacent six-membered rings. This loose crystal structure gives it an extremely low thermal expansion coefficient, and can be used as a lost foam refractory coating during the casting process, improving the precision of the casting.

4. Catalyst carrier

Cordierite has a loose crystal structure and a low thermal expansion coefficient, so it can be made into a porous cordierite catalyst carrier. The service environment of the catalyst carrier material is complex and has high requirements for material performance. In particular, the monolithic catalyst used for automobile exhaust treatment, during the operation of the engine, due to the effect of thermal shock, the temperature of the exhaust gas rises to about 700°C in a few seconds. When the engine stops, the temperature drops rapidly to the ambient temperature. A good automobile exhaust monolithic catalyst needs to repeat this process thousands of times, and the carrier needs to support the catalyst and ensure mechanical strength. Cordierite ceramics also have good thermal shock resistance, thermal shock resistance, chemical stability and certain mechanical strength, and are also widely used in water pollution treatment.

5. Microwave communication dielectric materials

Cordierite ceramics have a low dielectric constant and a near-zero frequency temperature coefficient. It is an ideal low-dielectric high-frequency microwave dielectric ceramic, which is used in the preparation of electronic packaging dielectric resonant antennas, microwave device substrates, high-end microwave components and other devices.

Compactness of Magnesia-Aluminum Spinel Rich in Magnesium Oxide

Application of magnesia-alumina spinel bricks in cement kilns. At present, the chromium-free measures taken by the new dry process cement kiln are mainly to replace magnesia-chrome bricks with magnesia-dolomite bricks, magnesia-alumina spinel bricks, and magnesia-iron-alumina spinel bricks (referred to as magnesia-iron bricks). Its kiln lining performance is very outstanding, and it is the best material to replace magnesia-chrome bricks in domestic cement kilns.

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The magnesia-alumina spinel bricks produced by introducing ferroalumina spinel into magnesia refractory materials provide a new lining concept for cement rotary kilns. Its good structural flexibility and excellent kiln lining performance provide it with high adaptability. In recent years, magnesia-alumina spinel bricks have been fully used in the high-temperature zone of cement rotary kilns. Rongsheng refractory manufacturer can provide high-quality magnesia refractory brick products for cement kilns, including magnesia-dolomite bricks, magnesia-alumina spinel bricks, and magnesia-alumina spinel bricks. Contact Rongsheng for a free quote.

Material Properties of Magnesia-Alumina Spinel

Magnesia-alumina spinel is one of the most important refractory materials in the steel and cement industries. It has gradually replaced chromium spinel and is also a popular refractory material in the above fields. However, magnesium-chromium alloys and Al2O3-chromium alloys are gradually decreasing due to the environmental hazards of hexavalent chromium. Magnesium-alumina spinel has excellent refractory properties such as high refractoriness, moderate thermal expansion, thermal shock stability and resistance to slag erosion.

The densification of spinel by primary firing requires very high temperatures (>1700℃) because the oxide composition is accompanied by a 7% volume expansion during the spinel formation process. On the other hand, the expansion during the spinel formation process is beneficial for Al2O3-MgO-C (AMC) bricks. Because the expansion during the in-situ spinel formation process minimizes the gaps between bricks and prevents metal infiltration.

The formation and sintering of spinel have been studied by different researchers by changing the raw materials and processing steps. Mansour et al. pointed out that the most spinel is formed when the calcination temperature of raw materials MgCO3 and Al(OH)3 is 900℃ and 1100℃ respectively. Gray believes that hydroxide contributes to the formation of spinel and the densification of magnesium-aluminum spinel. Kostic et al. found that fine grinding of raw materials will increase its specific surface area and increase its structural defects, which will lead to the formation of low-temperature spinel.

Magnesia-Rich Magnesia-Alumina Spinel

Magnesia-rich magnesia-alumina spinel is mainly used in cement kilns because of its compatibility with the products of cement formation process. Compactness of MgO-rich magnesia-aluminum spinel. Alper in the study of MgO-Al2O3 binary system showed that the solubility of MgO in the spinel phase was 39%. Bailey et al. found that the presence of excess MgO in the spinel phase would restrict the growth of spinel grains and promote sintering. Cooper et al. found that 40% MgO in magnesia spinel bricks would improve its thermal and corrosion properties. India has a large reserve of magnesia ore, which contains impurities such as CaO, SiO2 and Fe2O3 that limit its application at high temperatures. In the present study, natural magnesia ore has harmful impurities SiO2 and CaO. As a magnesia-rich magnesia-alumina spinel aggregate, it was developed and compared with the aggregate prepared by synthetic calcined magnesia.

Dense Magnesium Aluminate Spinel

Through various experiments, researchers have a unique understanding of dense magnesium aluminate spinel bricks.

1) The density of sintered spinel generated by Salem magnesite (SS) increases sharply between 1400℃ and 1500℃, followed by a slight decrease at higher temperatures due to liquid phase sintering. The spinel generated by caustic magnesia (NS) densifies slowly below 1500℃, followed by an improvement in density at 1600℃. The NS sample is densified by solid phase sintering.

2) X-ray diffraction analysis of the SS sample sintered at 1600℃ shows that spinel and periclase are the main phases, and forsterite is the secondary phase. This is because SiO2 exists in natural magnesite, while the NS sample only contains periclase and spinel phases.

3) As the temperature increases from 1500℃ to 1600℃, the flexural strength of the NS sample increases due to its more compactness. However, compared with the SS sample sintered at 1500℃, the flexural strength of the SS sample sintered at 1600℃ is lower, which is due to the presence of the low melting point phase and the uneven particle size distribution.

Application of 7-Hole, 19-Hole, 31-Hole and 37-Hole Checker Bricks in Hot Blast Furnaces

Lattice brick, this term may not be common in the daily life of ordinary people, but in the iron-making industry, it is widely recognized and accepted as a heat transfer and heat storage body with many superior thermal characteristics such as strong heat exchange capacity, large heat storage area, smooth ventilation, and low resistance. Rongsheng Checker Bricks, English name Lattice brick, is a heat transfer medium, mainly used in the upper and middle parts of the heat storage chamber of the hot blast furnace to store heat. In the process of heating cold air into hot air, lattice brick plays an extremely important role.

7-Hole, 19-Hole, 31-Hole and 37-Hole Hot Blast Furnace Checker Bricks

Checker bricks, the name may sound a bit mysterious, but it actually plays a very important role in industry. In hot blast furnaces, glass kilns and coke oven regenerators, it is like a passionate heat transfer messenger, helping hot and cold gases to complete heat exchange.

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So, what is so special about checker bricks? First of all, its design is very clever, with bricks with grid holes arranged in an orderly manner. These grid holes allow hot and cold gases to pass freely, thereby achieving efficient heat exchange.

The characteristics of checker bricks are also quite significant:

• Strong heat exchange capacity: can quickly transfer heat to cold gas.
• Large heat storage area: store more heat and reduce energy consumption.
• Smooth ventilation: ensure smooth passage of gas without affecting heat exchange.
• Good volume stability: can maintain the shape even at high temperatures.
• High-temperature load creep performance: the performance remains stable under high temperatures and high load.

According to the material classification, checker bricks can be divided into clay, high alumina, mullite, silica and sillimanite and other types. And according to the specification classification, there are 7 holes, 19 holes, 31 holes and 37 holes and other options.

Whether in hot blast furnaces, glass kilns or coke oven regenerators, checker bricks are an indispensable part. It not only affects the operating efficiency of the entire system, but also directly affects the safety and stability of production. Therefore, choosing the right checker brick is a crucial decision for every industrial producer.

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The Volume Stability of the Hot Blast Furnace Checker Brick is Good

The checker brick has multiple transparent grid holes parallel to the side surface, as well as positioning protrusions and positioning grooves on two parallel surfaces. These designs not only make it ventilated smoothly and with low resistance, but also greatly enhance its heat exchange capacity and heat storage area. In addition, the checker brick has good volume stability, excellent high temperature load creep performance, high density and low porosity, which enables it to maintain excellent performance under high temperature and high pressure working environment.

Blast furnace hot blast furnaces usually adopt a checker brick regenerator structure, which transfers heat to the checker bricks by passing the high temperature flue gas after combustion through the holes of the checker bricks. Then during the air supply period, the cold air is heated into hot air through the checker bricks, and then sent to the blast furnace through the hot air pipe for combustion reaction. The aperture and heating area of ​​the checker bricks have a direct impact on the performance of the hot blast furnace. The old blast furnace hot blast furnace uses standard checker bricks with an aperture of 40 mm and a heating area of ​​32.7 square meters per cubic meter. The Kalugin top-fired hot blast furnace uses checker bricks with smaller apertures and larger heating areas, such as checker bricks with an aperture of 30 mm and a heating area of ​​48 square meters per cubic meter, and checker bricks with an aperture of 20 mm and a heating area of ​​64 square meters per cubic meter. These improvements not only improve the thermal efficiency of the hot blast furnace, but also significantly reduce the amount of refractory materials used and investment costs of the hot blast furnace.

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With the technological development of the ironmaking industry in the metallurgical industry, increasing the air temperature of the hot blast furnace has become an important measure. The technological development of the Kalugin top-fired hot blast furnace has enabled the maximum air temperature of the blast furnace hot blast furnace to reach 1350 degrees. Under this trend, 20 mm aperture checker bricks have become the first choice for modern hot blast furnaces due to their higher heating area and lower dosage. In blast furnace hot blast furnaces in Russia, China, Kazakhstan, Ukraine and other places, 20 mm aperture checker bricks have been widely used.

The application of checker bricks is not limited to blast furnace hot blast furnaces, it is also used in other industrial fields such as flame furnaces. According to different temperature zones and technical requirements, checker bricks of different materials are generally selected, such as siliceous checker bricks, clay bricks, high alumina bricks, mullite bricks, sillimanite bricks, etc. These checker bricks provide strong heat exchange and heat storage capacity for industrial production with their unique structure and performance.

In general, checker bricks have become an indispensable and important material in the ironmaking industry with their superior thermal properties and wide application fields. Its design and application not only reflect the continuous exploration and innovation of human beings in industrial technology, but also provide more possibilities and opportunities for our future industrial production. Contact Rongsheng for more information.