Process method of Si₃N₄ ceramic brazing sealed cavity for high-temperature application

Area of Science:

• Materials Science
• Ceramic Engineering
• Vacuum Technology

Background:

• Silicon nitride (Si3N4) ceramics are crucial for high-temperature applications.
• Developing robust vacuum-sealed cavities for extreme environments remains a challenge.
• Existing sealing methods often fail under high thermal stress.

Purpose of the Study:

• To develop a reliable vacuum-sealed cavity using Si3N4 ceramic suitable for high-temperature environments.
• To investigate the bonding strength and thermal stability of the prepared sealed cavities.
• To enable the development of high-temperature pressure sensors.

Main Methods:

• Utilized vacuum brazing and chemical reaction at 1,100°C and 0.5 MPa.
• Employed Si3N4 ceramic polishing, thinning, and inductively coupled plasma etching.
• Applied high-temperature metal filler (Ti-Zr-Cu-Ni) brazing process.

Main Results:

• Successfully prepared a vacuum-sealed Si3N4 ceramic cavity.
• Characterization via SEM and EDS confirmed intact cavity structure and well-bonded Si3N4 ceramics.
• Bonding interface strength exceeded 5.13 MPa and remained stable at 1,000-1,100°C for 1 hour.

Conclusions:

• The proposed vacuum brazing method effectively creates durable Si3N4 ceramic sealed cavities.
• The sealed cavities exhibit exceptional thermal stability, suitable for high-temperature applications.
• This technique paves the way for manufacturing high-temperature resistant pressure sensors.