Sintering and application of silicon carbide ceramics

Sintering and application of silicon carbide ceramics

Silicon carbide ceramic materials have the advantages of wear resistance, corrosion resistance, high hardness, low density and high high temperature strength, so they are rapidly popularized and developed in various fields in recent years. In aerospace, nuclear industry, petroleum industry, chemical industry, textile industry, food industry and other special environments, such as high temperature, high speed, corrosion resistance, vacuum, electrical insulation, non-magnetic, dry friction and so on, the incomparable substitution of this new ceramic material is gradually recognized by people.

In addition to the above advantages, the content of free silicon and free carbon in atmospheric pressure sintered silicon carbide ceramics is very small. For example, in the fine chemical industry, in the process of ultra pure fluid transportation, high cleanliness is required. Atmospheric pressure sintered silicon carbide ceramic materials can provide a very reliable transportation environment and protect the transportation environment. With the enhancement of people's awareness of environmental protection, atmospheric pressure sintered silicon carbide ceramic materials will eventually replace reaction sintered silicon carbide products in the chemical industry.

At present, the atmospheric Sintering SiC ceramic materials mainly have the following aspects of application:

1、 Bearing assembly of sealed magnetic drive pump

With the rapid development of fine chemical products, especially the further implementation of the international standard ISO14000 in the fine chemical industry, it puts forward higher requirements for the elimination of running, emitting, dripping and leaking, and the environmental protection of the chemical industry, especially for the transportation of corrosive liquid. The pursuit of zero leakage has become the main goal of environmental protection in the chemical industry.

The sealed magnetic drive pump uses the non-contact magnetic drive mode to generate torque and drive the pump shafting components to work. Its main features are as follows: the larger space is reduced, and the overall volume of the pump is reduced by 20% - 30%; the non-contact drive mode is adopted, and the bearing and shafting components are all placed inside the pump body to implement the full sealing, so as to realize the leakage free work. In this condition, the bearing life determines the overall life of the pump.

The seal ring made of normal pressure sintered silicon carbide ceramic material is used to replace the general mechanical seal, packing seal and other dynamic seals, so that the leakage is smaller, the reliability is higher and the service life is longer. For magnetic pump, maintenance free for a long time is usually required, and the time is about 5-8 years, which puts forward extremely strict requirements for the material selection of magnetic pump shafting components. For example, the pump shaft, thrust plate and shaft sleeve in the pump must be wear-resistant, corrosion-resistant and zero leakage after assembly: at present, atmospheric pressure sintered silicon carbide ceramics has become the most suitable material of choice.

2、 Mechanical seal ring

The high chemical corrosion resistance, high strength, high hardness, good wear resistance, small friction coefficient, low oxidation resistance, low creep at high temperature and good thermal stability of the sintered SiC ceramics under atmospheric pressure are ideal materials for manufacturing sealing rings. Because of the dense structure of the material matrix, the free silicon is free; Carbon content is very small, and it is widely used in high purity, super clean, fine chemical industry and other fields. The ultra precision machining of workpiece surface makes the friction coefficient smaller than alumina ceramics and cemented carbide when combined matching, so it has higher PV value, especially suitable for the transportation of strong acid, strong alkali and corrosive liquid. High density (310G) of SiC ceramic products sintered at atmospheric pressure / cm3 - 320g / Cm3) high hardness ( HPA95 ) , can be a variety of products, into a batch production of various complex mechanical sealing rings, such as flat ring, single-sided step ring, multi-stage ring, etc.

3、 Sandblasting nozzle

As a new substitute for cemented carbide and alumina ceramic materials, atmospheric sintering silicon carbide ceramics has become the second only to boron carbide ceramics, and is the most widely used material in sand blasting industry. Although the alumina ceramic nozzle is cheap, it is only used in the case of small sand blasting because of its low hardness and poor wear resistance. In practice, the service life of the sintered SiC ceramics is 4-7 times of that of alumina ceramics, and it is also a substitute for the cemented carbide with large proportion.

4、 Bulletproof board

Since the invention of ceramic armor by the British chobam, atmospheric pressure sintered silicon carbide ceramics have been widely used in bulletproof armor, such as the protection of vehicles and ships, as well as the protection of civil insurance cabinets and cash carriers, due to their high hardness, small specific gravity, good ballistic performance, more energy absorption after fragmentation and low price. The ballistic performance of SiC ceramics sintered at atmospheric pressure is better than that of alumina ceramics, and the comprehensive strength is about 70-80% of that of boron carbide ceramics. However, due to its low price, it is especially suitable for the occasions where the amount of SiC ceramics is large and the protective armor cannot be too thick or heavy. Atmospheric pressure sintered silicon carbide ceramic has the characteristics of high strength and good toughness. As a bulletproof armor material, it has very good resistance to multiple attacks, so the overall protection effect is better than that of ordinary silicon carbide ceramic. When it is used in cylindrical ceramic lightweight protective armor, its breaking point can reach more than 65 tons, and the protection effect is obviously better than that of ordinary silicon carbide ceramic cylindrical ceramic Protective armor.


Atmosphere protection sintering furnace designed and developed by Shanghai Haoyue

Haoyue technology is a high-tech enterprise integrating R & D, production and sales of electric furnace. The company has been focusing on advanced ceramics and composite materials, semiconductor materials, carbon materials and lithium and new energy materials and equipment in four major fields, with rich industry experience and professional technology, dedicated to serving customers, providing perfect integrated industrial solutions.

Updated date: 2021-04-20

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