manufacturing process of piezoelectric ceramic
Publish Time: 2018-11-21 Origin: Site
(1) The process method of piezoelectric ceramics is to use a ball mill (drum type, planetary type, agitating type and vibrating type ball mill), and add grinding balls (steel balls, agate balls, zirconium balls, etc.) and media (water, alcohol, etc.) to the raw materials. It is mechanical mixing or communication.
(2) Process principle
The grinding ball generates the centrifugal force, the friction force and the gravity force by the motor to form a collision, a cycle turning and a rotation motion, so that the powder in between is subjected to impact and friction grinding, thereby achieving mixing and pulverization refinement.
(3) Ball milling process
The specific ball milling process depends on different ball mills. The reasonable process parameters should be optimized by the experimental results (mixing degree after ball milling, particle size and distribution, amount of mixing, efficiency and cost, etc.), and high powder piezo cylinder tube can also refer to relevant process parameters.
Ball mill speed (determined by ball mill type, ball mill tank size, etc.) 2 Ball mill tank (diameter, lining material, etc.)Grinding ball (specific gravity, hardness, shape, wear rate)= powder filling amount (about 60%).The ratio of powder, ball and grinding media (determined by the water absorption of the piezoceramic tubes transducer and the specific gravity of the ball) . The role of grinding media (adhesion, splitting, flow, dispersion, etc.) Ball milling time (depending on the type of ball mill, feed particle size) And) ball milling method (dry, wet).Pre-firing (also known as synthesis) is a process in which a solid phase chemical reaction is completed by diffusion of atoms or ions in a raw material under heating to form a piezo ceramic.
Pre-burning process: Mounting is to mix the dried powder into the crucible, and press, puncture, cover and enter the furnace. The front door of the 500 °C is slightly opened to facilitate the removal of organic matter and moisture, and then the furnace door is closed. 2) Heating conditions (taking typical PZT as an example) Heating rate: depending on the amount of charge in the furnace. Maximum temperature: 850 °C (depending on the formula). Holding time: 1-2 hours at 650°C to generate PT. The temperature was maintained at about 850 ° C for 2 hours to generate PZT. Cooling rate: The power of soft PZT piezoceramic tubes crystal is turned off with the furnace and is discharged below 200 °C. Furnace atmosphere: Neutral or oxidizing atmosphere is preferred; reducing atmosphere will cause the powder to be reduced and blackened, and must be strictly controlled. The silicon carbon rod furnace is better than the resistance wire furnace.
Quality requirements for pre-fired porcelain:
Appearance: The color is normal and uniform; there is a certain expansion or contraction (depending on the specific formula of small piezo tubes transducer); the hardness is moderate. Chemical analysis: less free zirconium, titanium, lead is less than 0.5% phase analysis.it is perovskite phase, no impurity phase. Factors affecting calcination .The relationship between feedstock activity and particle size is in the 2012QkTrtDe formula, where t is the time required for the solid phase reaction; r is the particle diameter; D0 is the diffusion frequency factor; Q is the activation energy; Temperature; k is a constant. This indicates that the rate of the solid phase reaction is proportional to the diffusion state (D0), activity, and temperature of the raw material, and inversely proportional to the average diameter of the raw material particles. Synthesis temperature (described above). Heating rate and holding time. blank pressing force. Furnace temperature uniformity, atmosphere, etc.