Reaction bonded SiC is made by infiltrating compacts made of mixtures of SiC and carbon with liquid silicon. The silicon reacts with the carbon forming more SiC which bonds the initial SiC particles.
Silicon carbide properties
Silicon carbide (SiC), also known as carborundum, is a semiconductor containing silicon and carbon.
The characteristics of the elastic modulus and thermal expansion are given by the characteristics of the SiC crystal itself, and the thermal conductivity or thermal diffusivity of the silicon carbides tends to be substantially higher than those of the other structural ceramics. The combination of a high elastic modulus and moderate coefficient of thermal expansion makes the SiC susceptible to thermal shock damage. The resistance to thermal shock is significantly lower than that of silicon nitride, but higher than the structural zirconia ceramic. The behavior before thermal shock is also very dependent on the application. For example, very rapid temperature changes can lead to a preference for Si3N4 over SiC, while for moderate rates of temperature change the high thermal conductivity of SiC can lead to better performance.
New multiphase silicon carbide ceramics
The new multi-phase silicon carbide ceramic is made of silicon carbide as the main raw material, through reasonable particle assembly, adding silicon powder, alumina powder and binder, and then kneading, molding, drying and high-temperature sintering. It has excellent properties such as high hardness, good wear resistance, thermal stability and chemical corrosion resistance, especially it is insensitive to abrasive angle of attack. The new multi-phase silicon carbide ceramic is affixed as an lining material or embedded in the surface of related equipment, which can greatly improve the wear and corrosion life of the equipment. The abrasion resistance of the wear-resistant particles is three times that of alumina (corundum) ceramics and five times that of high-alloy wear-resistant cast steel. Therefore, it is widely used in thermal power, coal, mining, metallurgy, chemical, cement, port and other fields, and is currently a cost-effective wear-resistant material.
Structure: Silicon carbide ceramics are lined in ordinary carbon steel pipes to form silicon carbide/steel composite pipes. The inner lining silicon carbide adopts the unequal thickness eccentric circular structure type, that is, the outer side of the curved pipe and the lower half of the straight pipe are slightly thicker, so that the wear life of each part of the pipe is the same, and the waste is reduced. The outer side of the silicon carbide is wrapped with FRP to increase the overall strength level. The transition section can be made of ordinary carbon steel pipe or oxygen-aluminum composite wear-resistant steel pipe or flanged according to user requirements. Can be made into a straight tube or a shrimp waist bend.
Scope of application: Low-impact and strong abrasive wear such as conveying powder, block material and ash residue working at 450 °C and 1.0 Mpa.
Performance characteristics: The comprehensive performance is good, the silicon carbide ceramic has a very high wear resistance, and has certain impact resistance and adhesion performance after the outer glass fiber reinforced plastic. The use of steel pipe as the outer casing not only improves the mechanical strength and impact resistance of the pipe, but also facilitates installation and welding. The service life of the product is 3-5 times that of alloy cast steel pipe, cast stone pipe and alumina ceramic composite pipe, generally up to 60,000 hours, and has a very high performance price ratio.
Exponential parameters:
| Item | Unit | Data |
| Max Temperature of Application | ℃ | 1380℃ |
| Density | G/cm3 | ＞3.02 |
| Open Porosity | % | ＜0.1 |
| Bending Strength | Mpa | 250 (20℃ ) |
| MPa | 280 (1200℃ ) | |
| Modulus of Elasticity | GPa | 330 (20℃ ) |
| GPa | 300 ( 1200℃ ) | |
| Thermal Conductivity | W/m.k | 45 (1200℃ ) |
| Coefficient of Thermal Expansion | K-1×10-6 | 4.5 |
| Moh's Scale of Hardness | 13 | |
| Acid Alkaline-proof | excellent |
Features
Silicon carbide ceramic pipe is made of silicon carbide as the main raw material, adding a variety of chemical wear-resistant raw materials and antioxidants, effectively improving the wear resistance of the product to Si0. A high-performance silicon carbide product that is fired at a high temperature by making a high-temperature bonded phase.
Has the following characteristics:
- Stable size, deformation resistance and high temperature strength at high temperature;
- Resistance to thermal shock, abrasion and corrosion;
- Anti-oxidation, erosion resistance.
Working condition of silicon carbide ceramic wear-resistant pipe
Metallurgy and power industry: The reason why these two industries are put together is mainly because the two industries have a large number of metal pipes for the transmission of coal powder, ash, mud, and the like. After using the wear-resistant elbow pipe, the advantages of strong wear resistance, long life and easy installation are immediately highlighted.
Mining industry: If the wear-resistant elbow pipe is not used, the ordinary pipe is used for the transportation of the ore powder. Due to the filling of the mine and the transportation of the concentrate powder, the wear of the pipe is relatively large, so that the life of these pipes is only about one year. After wearing elbow pipes, the life of such pipes will be extended by a factor of five.
Coal industry: If long-distance wet transport of coal is required, the pipe has the requirements of good wear resistance and high corrosion resistance, and the pipe with wear-resistant elbow can meet these requirements well.
Advantages of silicon carbide ceramic liner and metal composite pipe:
- High strength: as the outer wall of the composite steel pipe is made of common ordinary steel pipe, the strength requirements of various processes are fully satisfied, under the support of the outer wall steel pipe.
- High wear resistance: Most of the inner wall of the steel pipe is a high wear-resistant ceramic which are selected according to the process requirements. The ceramic content is more than 95%. Thus, the product has good wear resistance.
- High anti corrosion: As the composite layer is made of corrosion-resistant materials, it seems to solve the main problems. It can be widely used in sites containing acid, alkali and salt.
- High bond strength: The matrix of the composite is made of organic polymer. On the basis of inorganic ceramic as a reinforcing agent, it is articulated under the environment of specific temperature, pressure and proper vacuum. At the same time, together with the inner wall of the steel pipe, the peeling strength is up to 14-16 MP which is is more than 100 times of the ordinary lining pipe. However, the difference of thermal expansion coefficient of composite layer leads to the phenomenon of inner liner falling off.
- Weather ability: This product can be used for 40 to 200 degrees for a long period of time. It can be as high as 260 degrees. This product is widely used in environmental protection, electric power, chemical industry, metallurgy, mining and other industries. It is an ideal substitute for lining plastic pipes.
And it has developed rapidly. When transporting the materials with the harder abrasion (such as ash dregs, slag, coal powder, mining dregs, the rest mines, cement, etc), it will exit the problem that the abrasion of pipes is too rapid. Especially, the abrasion of bent pipes is greatly more rapid.
When transporting the special abrasion materials or erosive materials, it will exit the problem that the damage of pipes is too rapid.
SiC Ceramic lined pipe and the traditional steel pipe, wear-resistant alloy cast steel pipe, cast stone pipe and steel, steel and other rubber pipe is essentially different. Ceramic lined pipe is the outer layer of steel, the inner layer is RBSiC ceramic. Moh’s hardness of up to 13. Wear resistance than carbon steel pipe more than 30 times higher.
At present, the use of our company’s high wear-resistant ceramic lined steel pipe dozens of thermal power plant practice shows that: ceramic lined steel pipe anti-wear ability, anti-fluid erosion ability.
In a duct, the elbow wear the fastest, in practice, Ceramic lined pipe used after 1 to 2 years to open the observation and measurement, the composite layer are no obvious wear or tear off, ceramic-coated steel pipe wear Than the thick-walled wear-resistant cast steel pipe increased by nearly 10 times.