SSIC Thermocouple Protection Tube

The pressureless sintered silicon carbide thermocouple protection tube has the characteristics of oxidation resistance, high thermal conductivity, corrosion resistance, thermal shock resistance and excellent high temperature strength, etc.

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It can withstand high temperature and the erosion of strong corrosive substances, which is the best material for making thermocouple protection tube. Silicon carbide thermocouple protection tube is usually used with the thermocouple, thermostat, thermometer, etc., mainly for protecting the sensor from being damaged by external forces, preventing the internal components from being corroded by harmful substances in the environment, and quickly and accurately transferring heat energy. Silicon carbide has a strong ability in heat resistance, oxidation resistance, heat shock resistance, wear-resistance and chemical stability, etc. It is an ideal material for a high-performance thermocouple protection tube.

At present, there are two series silicon carbide products of pressureless sintering silicon carbide (SSIC) and reaction sintering silicon carbide (SISIC), which are widely used in mining, metallurgy, chemical industry, electric power, petroleum, furnace, machinery, steel, energy, environmental protection, building materials, semiconductor, aerospace and other fields. Compared with reaction bonded silicon carbide, pressureless sintered silicon carbide has higher purity, better mechanical properties, more prominent corrosion resistance(Resistant to strong acid and alkali corrosion, It is also the only ceramic material which can resistant to hydrofluoric acid corrosion), higher wear resistance, because of there’s no free silicon in the material. It can be used longer service life in environments which other materials not meet.

Silicon carbide (SiC) is a lightweight ceramic material with high strength properties comparable to diamond. It has excellent thermal conductivity, low thermal expansion, and is resistant to acid corrosion. Silicon carbide is an excellent ceramic material suitable for applications requiring good corrosion resistance and wear resistance.

Silicon carbide is formed in two ways, reaction bonding and sintering. Each forming method greatly affects the end microstructure.

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.

Sintered SiC is produced from pure SiC powder with non-oxide sintering aids. Conventional ceramic forming processes are used and the material is sintered in an inert atmosphere at temperatures up to 2000ºC or higher.

Both forms of silicon carbide (SiC) are highly wear resistant with good mechanical properties, including high temperature strength and thermal shock resistance. Our engineers are always available to best advise you on the strengths and weaknesses of each ceramic for your particular needs.

The crystal structure of the SiC ceramic wear-resistant pipe is similar to that of the diamond tetrahedral structure. It is a compound composed mainly of covalent bonds. Its hardness is high (Mohs 9.3), its performance is stable, and its physical properties are similar to diamond. It is also known as emery. Black silicon carbide crystal Hardness is the second-order material for diamonds. It is mainly used for making abrasives and grinding wheels, and partly for the production of silicon carbide ceramics.

Properties

Silicon carbide (SiC) ceramics have a set of unique physical-chemical properties, such as high hardness and mechanical stability at high temperatures, excellent thermal conductivity and low coefficient of thermal expansion, high resistance to corrosion and oxidation, wide bandgap, and others.

• High hardness (second only to diamond)
• Low density 40% the density of steel – approximately the same as aluminium
• Low porosity
• Good wear resistance in sliding and abrasive environments
• Excellent corrosion resistance in most chemical environments
• Low thermal expansion and high thermal conductivity leading to excellent thermal shock resistance.

Properties of reaction bonded silicon carbide

Reaction Bonded SiC has the lowest cost production technique with a course grain. Reaction Bonded SiC provides somewhat lower hardness and use temperature, but higher thermal conductivity. Reaction bonded silicon carbide has high strength, high hardness, hig abrasion resistance, high temperature resistance, corrosion resistance, good oxidation resistance, good thermal shock resistance, good thermal conductivity, rapid cooling and rapid heat resistance and high temperature creep resistance, etc. It can be made into beam, roller, cooling air pipe, thermocouple protection pipe, temperature measuring pipe, burner nozzle, wear-resisting parts, corrosion-resisting parts, sealing parts and a variety special-shaped structural parts.

Properties of pressureless sintered silicon carbide

Compared with reaction bonded silicon carbide, pressureless sintered silicon carbide has higher purity, better mechanical properties, more prominent corrosion resistance ( Resistantto strong acid and alkali corrosion, It is also the only ceramic material which can resistant to hydrofluoric acid corrosion ), higher wear resistance, because of there’s no free silicon in the material can be used in other materials can not meet the environment, longer service life.

Advantages

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.

1. 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.
2. 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.
3. 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.
4. 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.
5. 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.

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.

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.