Effect of sintering activation energy on Si3N4 composite ceramics

Preparation of 3D printed silicon nitride bioceramics by microwave sintering

“…In addition, due to the fact that both HPS and GPS belong to external heating, the heating element heats up the Si 3 N 4 material sample through thermal conduction or radiation. Therefore, there exists a local process of heating first and then gradually from the outside to the inside, which not only makes the degreasing process long-time, has multiple procedures, and has a high probability of defects, but also leads to inconsistent and uneven time for the liquid phase generation of internal sintering aids, resulting in irregular crystal structure growth under the action of the liquid phase during the Si 3 N 4 crystal phase transformation process, which has the significant effect on material performance 42 , 43 . …”

“…Compared with the HPS temperature of 1650 °C and the GPS temperature of 1700 °C, the phenomenon of volatilization and decomposition of samples during microwave sintering is significantly reduced. The overall self-heating method of Si 3 N 4 material effectively ensures the high uniformity of material heating, the uniform removal of organic binders, the uniform generation of liquid phase, and the uniform transformation of Si 3 N 4 crystal phase 42 . During the crystal phase transformation, the improvement of the uniform liquid phase effect allows the Si 3 N 4 crystal to grow fully, forming a more perfect and ideal Si 3 N 4 crystal structure with longer diameter, and the comprehensive mechanical performance of Si 3 N 4 material has been significantly improved 46 .…”

Sintering activation energies of anisotropic layered and particle alumina/zirconia-based composites and their mechanical response

“…Three types of ceramic materials were prepared i) monoliths (standardsnominally pure alumina or zirconia denoted as A and Z) ii) particle composites (i.e., homogeneous mixture of alumina and zirconia with given volume fraction), and iii) layered composites (i.e., alternating alumina and zirconia layers with various thickness). The particle composites (denoted as PC) were prepared by mixing of certain volume fraction of zirconia (i.e., 17,25,33,45,50,55,66,75, and 83 vol.%) into alumina. The depositions lasting 30 min were interrupted each 5 min and the suspensions were thoroughly stirred to prevent sedimentation of the particles.…”

“…A lot of works have been published up to now to establish activation energies of nominally monolithic ceramics. The most attention was paid to alumina [1][2][3][7][8][9][10][11][12][13], zirconia [3,7,9,[14][15][16], silicon nitride [17], zinc oxide [8], uranium dioxide [18,19], yttrium oxide [20], etc. Moreover, it was found that the sintering technique can also play a role in diffusion mechanisms in studied materials affecting the activation energy of sintering [8].…”

“…Moreover, it was found that the sintering technique can also play a role in diffusion mechanisms in studied materials affecting the activation energy of sintering [8]. Therefore, not only conventional sintering [1][2][3][7][8][9] but also microwave sintering [8], sintering in microwaveinduced oxygen plasma [21], spark plasma sintering [22], and liquid phase sintering [17] were considered to report complex data concerning activation energy of sintering at different conditions.…”