Boron Carbide Ceramic Properties And Application
Boron carbide ceramic is an critical a part of new ceramics, which has a high melting point, excessive hardness, low density, wear resistance, and corrosion resistance. it's miles broadly used within the subject of nuclear strength, bulletproof armor, and wear-resistant materials.
At present, the depth and energy of the research on boron carbide ceramics are growing. further to the emergence of recent methods for the synthesis of high-purity and extremely-first-rate boron carbide powder, researchers also are dedicated to the development of superior and realistic sintering generation.
Ceramics boron carbide characteristics
Boron carbide ceramics are very difficult. Its microhardness is set 50000mpa (50gpa), subsequent to diamond (ninety-100gpa), and CBN (eighty-90gpa). Its grinding efficiency can attain 60% - 70% of a diamond, 1-2 instances of SiC, 1-2 times of corundum's grinding capacity. It has extremely good acid-base resistance and a small coefficient of thermal enlargement (4.5x10-6 ℃), so it has awesome thermal balance. it is able to take in thermal neutron qualitatively, but it has a vulnerable effect on resistance and high brittleness.
Boron carbide can resist air corrosion at a thousand ℃, however it is simple to oxidize in an oxidation environment at higher temperatures. Boron carbide has a excessive resistance to acid and alkali, and isn't wetted through maximum of the molten metals, and has excessive balance in contact with these materials.
instruction of boron carbide ceramics
Boron carbide ceramics may be created through various methods. To acquire dense B4C, hot pressing sintering is commonly used.
The B4C acquired by means of hot pressing sintering can attain 98% of the theoretical density. The training is accomplished in a vacuum burning urgent furnace or a widespread fiery urgent furnace. the nice and cozy pressing temperature is 2100 ℃, the stress is 80-100mpa, the temperature is saved for numerous minutes, and the pressure needs to be maintained when the warmth is reduced.
due to the vulnerable thermal shock resistance of B4C, the cooling need to be gradual. the hot urgent temperature should no longer be too excessive. while it reaches 2150 ℃, the B4C-C eutectic liquid phase will seem, but if the temperature is just too low, the product density will below. Boron carbide ceramic merchandise with high density and hardness may be received through the usage of B4C ultrafine powder.
In addition to warm urgent sintering, there is no pressing sintering. however the requirements of pressureless sintering for carbide powder and sintering temperature variety are very excessive. The consequences display that an vital condition for the densification of natural boron carbide through pressureless sintering is to apply ultrafine powder ≤ 3um, and the oxygen content is low enough. The sintering temperature range is 2250-2350 ℃.
The number one way of pressureless sintering with additives is to eliminate the oxide layer of boron carbide through components, to improve the activation of grain boundary and volume diffusion by using increasing the density of point defects or dislocations, to reap a higher frequency (90-ninety five%) at a barely lower temperature (2000-2200 ℃). The effects show that once Al and Si are used as sintering aids respectively and sintered at 2050 ℃ and atmospheric strain for 180min, the relative density of the composite ceramics is extra than ninety three%, such as 298mpa bending energy of the boron carbide ceramics containing Al and 344mpa bending electricity of the boron carbide ceramics containing Si.
Except, there also are warm isostatic pressing sintering and discharge plasma sintering techniques for boron carbide ceramics, in order to now not be defined right here. but, warm pressing is a preferred approach to prepare natural boron carbide ceramics.
utility of boron carbide ceramics
1. Bulletproof armor subject
Because of its lightweight, awesome high hardness, and high elastic modulus, B4C ceramics are the satisfactory substances for a bulletproof vest, helmet, and armor.
At present, boron carbide ceramics are widely used in ceramic armor materials. compared with different bulletproof substances, B4C ceramics are lighter and more tough. it's far particularly appropriate for armed helicopters and other aircraft as bulletproof armor materials, that can successfully face up to shells. Boron carbide ceramics, produced with the aid of BAE systems advanced Ceramics, had been used because the "interceptor" bulletproof garb for the united states army.
2. Wear-resistant era
Inside the discipline of wear-resistant era and engineering, diverse nozzles made of B4C with excessive hardness are used for the desander nozzle and the nozzle for excessive-stress jet water cutting of deliver rust elimination. Boron carbide is used as the abrasive material for other hard substances along with cemented carbide and engineering ceramics in the technique of sharpening, satisfactory grinding or grinding, which could notably reduce the cost of grinding process.
3. Thermoelectric couple
Based totally on the thermoelectric belongings of B4C, a temperature differential couple able to measuring 2200 ℃ become prepared via sintering in Japan and Germany, which changed into used for the measurement and manipulate of excessive temperature. because of its excessive thermal electricity and balance, it is able to be used reliably for a long time, and the temperature may be measured repeatedly.
Boron carbide ceramics is a great deal good sized, which has many great houses and has been widely used. And in the future, it will be greater.
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