Why Choose Our Vacuum Sintering Furnaces

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Application of vacuum technology in ceramic sintering

Vacuum sintering is the most critical link in the preparation process of advanced ceramics. Its essence is the process of eliminating pores in the green body and completing densification. The sintering process has a direct impact on the grain size and pore content, and determines the final performance of advanced ceramic samples. Advanced ceramic preparation technology has developed at least, and there are many sintering methods. According to different factors such as pressure and sintering atmosphere, it can be divided into vacuum sintering, hot pressing sintering, etc. In these sintering methods, vacuum technology plays an important role.

1.Vacuum sintering

During the vacuum sintering process, the influence of atmosphere is complex and important. Sintering atmosphere is generally divided into three types: oxidation, reduction and neutral. Generally speaking, reducing atmosphere promotes the detachment of anions from the crystal surface, increases the diffusion coefficient, and is conducive to sintering; while oxidizing atmosphere is conducive to the diffusion of cations. Since oxide sintering is mostly controlled by O2 diffusion, reducing atmosphere (especially vacuum) is more suitable. Vacuum also promotes the discharge of gas inside the green body and accelerates densification, so that dense ceramics can be obtained by heating in a vacuum atmosphere.

The emergence of vacuum sintering technology has laid a technical foundation for the development of a variety of optical functional ceramics.

2.Vacuum hot pressing sintering

Hot pressing sintering is a process of applying pressure to powders that are difficult to sinter in a mold and sintering them at the same time. The mold is required to be conductive and pressure-resistant. Currently, graphite is the most widely used mold material. Graphite is easily oxidized at high temperatures, and it happens that the service life of graphite can be well extended under closed vacuum conditions. At the same time, vacuum conditions can promote the diffusion of anions. Therefore, vacuum hot pressing sintering has become an important sintering method.

Photofunctional ceramics can be prepared by vacuum hot pressing. The assistance of external pressure can effectively promote densification, shorten sintering time, and reduce energy consumption. In addition, for other ceramics that are difficult to sinter densely under normal pressure, vacuum hot pressing technology has also achieved better performance, such as the widely used ZnO and MgO ceramics.

Vacuum hot pressing sintering refers to pressurizing while sintering, which is conducive to contact between particles and flow mass transfer, reduces the sintering temperature, shortens the production cycle, and is widely used for the rapid preparation of silicon carbide ceramics. The vacuum hot pressing sintering furnace is a device that combines vacuum, atmosphere, hot pressing and high temperature sintering. It is suitable for high temperature hot forming of new materials such as powder metallurgy and functional ceramics. For example, it is used for vacuum sintering of metals such as transparent ceramics, industrial ceramics, and alloy materials composed of refractory metals, as well as high temperature sintering of ceramic materials such as silicon carbide and silicon nitride. It can also be used for heat treatment of powders and pressed blanks at a temperature below the melting point of the main components, with the purpose of improving their strength through metallurgical bonding between particles.

The vacuum hot pressing furnace is composed of a furnace body, a furnace cover, a heating and heat preservation and temperature measurement system, a vacuum system, an inflation system, a water cooling system, a control system, and a pressurization system. The upper pressure head is composed of an upper water-cooled pressure head and an upper graphite pressure head, and the lower pressure head is composed of a lower water-cooled pressure head and a lower graphite pressure head. The upper pressure head and the lower pressure head are inserted into the furnace body from the pressure head through holes on the upper and lower end surfaces of the furnace body and the heating chamber, respectively, and the upper graphite pressure head and the lower graphite pressure head are inserted into the heating chamber respectively, and the upper pressure head and the lower pressure head can move up and down.

Vacuum Hot Pressing Furnace

Spec\Model	RVP-3312	RVP-5513	RVP-5518
Working Zone Size (W*H*L)	320*320*1200mm	500*500*1300mm	500*500*1800mm
Max. Weight	250Kg	500Kg	800Kg
Max.Temperature	1800°C	1800°C	1800°C
Temperature uniformity under vacuum	±5°C	±5°C	±5°C
Temperature uniformity under pressure	±7.5°C	±10°C	±10°C
Heating Power	210Kw	300Kw	360Kw
Ultimate Vacuum	2Pa	2Pa	2Pa
Pressure Rising Rate	0.67Pa/h	0.67Pa/h	0.67Pa/h
Working pressure	20/60/100Bar	20/60/100Bar	20/60/100Bar
Process gas	Ar/N2/H2/CH4	Ar/N2/H2/CH4	Ar/N2/H2/CH4
The above specifications are defined according to cemented carbide part. The above parameters can be adjusted to the process requirements, they are not as acceptance standard, the detail spec. will be stated in the technical proposal and agreements.