Factors that affect sintering
2018-02-28
(1) crystallization of the chemical properties of the material
Lattice energy: large lattice energy, strong bond strength, firm structure, high temperature particle mobility, sintering difficult;
Cationic Polarity: Ions of little cationic polarity are difficult to sinter
Grain growth rate: grow 50 times, the relative density of 95%, grow 1500 times, the relative density of 60 to 80%
The second phase precipitates, grain growth 50 microns, the relative density of less than 90%.
(2) material dispersion (crush): the larger the surface area of the powder, the stronger the particle mobility, the higher the sintering activity
(3) sintering temperature and holding time
Linear relationship (sintering temperature ↑, holding time ↑, sintering speed ↓, but too much to improve the sintering temperature, prolonging the sintering time of no use.
(4) the compact body (to strengthen the contact between the particles)
Promote plastic flow at high temperatures; accelerate diffusion of particles (increase the number of defects).
5) admixture
(6) increase the porosity of the gas phase (sinter formation of isolated pores) Adsorption of gas film (impede direct contact, affecting mass transfer)
(7) atmosphere gas solubility in the solid phase is large, can promote sintering, or sintering does not benefit.
