Silicon carbide ceramics are a kind of material with high strength, high thermal conductivity, acid and alkali corrosion resistance, it can adapt to the external environment well in the process of use, and is considered by the industry to be the best anti-corrosion heat exchange material. The strength of ordinary ceramic materials will decrease significantly at 1200~1400 °C, while the flexural strength of silicon carbide ceramics will remain at a high level of 500~600MPa at 1400 °C, and its working temperature can reach 1600~1700 degrees Celsius, and will not be melted and damaged, with strong stability, high thermal conductivity, ultra-high temperature stability, and stable structural properties. Silicon carbide ceramics are particularly prominent in chemical heat exchange applications.
Silicon carbide ceramic heat exchanger tubes
Silicon carbide ceramic heat exchanger
Silicon carbide ceramics have comprehensive anti-oxidation ability and anti-corrosion ability, and are recognized as "dream-type" heat exchange materials in the field of chemical anti-corrosion, and also have high insulation properties. Compared with traditional graphite, fluoroplastics, precious metals, glass-lined and other heat exchange materials, its heat exchange efficiency and service life have obvious competitive advantages, especially in some composite strong acid environments, its super corrosion resistance is irreplaceable, and plays an increasingly important role in promoting the improvement of equipment and technology in related fields.
Silicon carbide ceramic heat exchangers have the following advantages:
- The use of silicon carbide ceramic heat exchanger is straightforward, simple, fast, efficient, environmentally friendly and energy-saving. It does not need to be protected by cold air and high temperature, and the maintenance cost is low, and there is no need to operate it. The waste heat recovery and utilization of gas industrial kilns suitable for various environments especially solves the problem that the waste heat temperature of various high-temperature industrial kilns is too high to be utilized;
- The state requires that the temperature of the ceramic heat exchanger ≥ 1000 °C, because it is resistant to high temperature, so it can be placed in the high temperature area, the higher the temperature, the better the heat exchange effect, the more energy saving;
- Metal heat exchanger can be replaced at high temperature;
- Solve the problem of heat exchange and corrosion resistance in the chemical industry;
- Strong adaptability, high temperature resistance, corrosion resistance, high temperature strength, good oxidation resistance, stable thermal shock performance, and long service life.
The application of new processes is imperative
With the introduction of more national energy-saving and emission reduction policies, as well as the accelerated upgrading and development of chemical, metallurgical and other industries. The molding process of traditional ceramics has been difficult to meet the application trends of new processes, new products and new markets. The traditional ceramic molding process requires the help of molds to prepare ceramic products with a certain shape and strength, which is time-consuming and costly. Compared with traditional molding technology, 3D printing ceramic technology has intelligent, moldless, precise, and high-complexity manufacturing capabilities, and it can complete manufacturing that is impossible to complete with traditional processes.
Comparison of the characteristics of traditional ceramic molding and 3D printing molding process
The preparation of silicon carbide ceramics is also an important challenge for the 3D printing technology of special ceramics. Because silicon carbide ceramic materials will have defects during the molding process, such as porosity, cracks, inhomogeneity, etc., it is difficult for molded ceramic devices to resist brittle fracture, which greatly limits their mechanical properties. However, silicon carbide ceramic components with complex geometries are often difficult to manufacture with traditional processing technology, which greatly restricts the application of silicon carbide ceramics with complex structures.
A new approach – powder extrusion 3D printing
Starting from the blank forming process of silicon carbide ceramics, combined with the appropriate sintering process, the sintered silicon carbide ceramic blanks can reach near net shape, so as to reduce the amount of subsequent processing and ensure that the product performance meets the requirements of use, which will become the main research direction of the preparation process of silicon carbide ceramics with complex structure. Through its self-created powder extrusion printing technology (PEP) combined with the reactive sintering process, Shenghua 3D has realized the integrated manufacturing of silicon carbide heat exchange plates/blocks. This provides a new way to realize the near-size, lightweight and integrated preparation of silicon carbide ceramic heat exchange parts.
3D printed silicon carbide heat exchange plate/block (source: Shenghua 3D)
PEP technology is a metal/ceramic indirect 3D printing process combining "3D printing + powder metallurgy" launched by Shenghua 3D, which has the characteristics of low-temperature molding and high-temperature formability. This process reasonably avoids 3D printing with laser as the energy source, and adopts particle melt extrusion molding, and its extrusion nozzle system is simple in structure and operation, which better reduces the input cost. By printing the green billet first, and then going through the mature powder metallurgy debinding and sintering process, the silicon carbide structural parts with excellent structural properties are obtained.
In the preparation of silicon carbide thermal management devices, Shenghua 3D uses the advantages of PEP technology to realize the lightweight and integrated design and molding of silicon carbide heat exchanger structural parts by 3D printing method based on the self-developed carbon carbide particle material UPGM-SiC, and prints green billets with certain strength and density. Combined with the debinding and reactive sintering process of ceramic injection molding, the components with stable mechanical properties and near-net size were obtained. Its weight has been greatly reduced, it does not deform during use, the consumption of gas is reduced, and the service life is extended. In addition, the PEP printing process can optimize the heat exchanger structure more reasonably, so as to solve its common thermal compensation and gas sealing problems. It can significantly improve the energy-saving effect and further increase the production capacity.
Performance parameters of reactive sintered silicon carbide ceramics (source: Shenghua 3D)
Silicon carbide heat exchange components, with high strength, high temperature resistance, high thermal conductivity and comprehensive acid and alkali corrosion resistance, can be used as an excellent alternative to graphite, stainless steel, tantalum metal, Hastelloy, fluoroplastics and other traditional materials, its excellent heat exchange efficiency can meet the urgent needs of energy saving, emission reduction and environmental protection. It is the best choice and inevitable trend for heat exchange applications in high temperature, high pressure, strong corrosion, high wear and extreme environment in chemical, pharmaceutical, metallurgical and other industries.
As the pioneer and leader of China's metal and ceramic indirect 3D printing technology, Shenghua 3D now has the ability to prepare complex structural parts of silicon carbide ceramics, and is actively exploring more application fields. The company has built a ceramic 3D printing pre- and post-processing process with independent intellectual property rights, covering the whole process chain equipment such as material development, printing material mixer granulator, 3D printer, degreasing and sintering furnace, etc., and provides high-performance indirect 3D printing overall solutions and printing services for the application market.
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