Microstructure and mechanical properties of silicon nitride ceramics prepared by pressureless sintering with MgO–Al2O3–SiO2 as sintering additive

The Carbothermal Reduction of Silica with Y2O3-MgO Powders

“…MgO-Y 2 O 3 was added into SiO 2 by CRN process in this technique, therefore the nanosized α-rich Si 3 N 4 is produced with a homogeneous additives distribution in the structure at low temperature (1400 • C-3 h). Adding a rare earth alone (< 10 wt%) is not as effective as sintering aid concurrent additions of rare earth and metal oxides are usually done to increase the sinterability [19]. When the synthesizing conditions (amount and type of additives and temperature) are compared with the previous works [12,13,20], it is seen that these conditions are better.…”

Microstructure and Properties of Porous Si3N4/Dense Si3N4 Joints Bonded Using RE–Si–Al–O–N (RE = Y or Yb) Glasses

“…Dense silicon nitride (D-Si 3 N 4 ) ceramics are considered to be important structure materials applicable for various industry parts [1] for its superior high temperature strength, thermal shock resistance, low thermal expansion coefficient, good wear, and corrosion resistance [2][3][4]. The porous Si 3 N 4 (P-Si 3 N 4 ) ceramics are emphasized for some engineering applications such as catalyst supports and gas filters due to its high mechanical strength, low dielectric constant, low density, and porous nature [5][6][7][8].…”

Investigation of the effect of ZrO2 and ZrO2/Al2O3 additions on the hot-pressing and properties of equimolecular mixtures of α- and β-Si3N4

“…The a-Si 3 N 4 , particles dissolve in the liquid and precipitate as b-Si 3 N 4 , via a reconstructive phase transformation. While sintering continues, the b-Si 3 N 4 , nuclei grow as elongated grains and form an interlocked grain structure [9,15,16,18,24,[27][28][29][30][31][32][33][34][35][36][37][38]. It has been noted that fully dense objects cannot be produced without the use of sintering additives.…”

“…It has been noted that fully dense objects cannot be produced without the use of sintering additives. As previously mentioned, the type and amount of sintering additives determine the nature and the properties of liquid formed [9,15,16,18,23,[27][28][29][30][31][32]. Al 2 O 3 , Y 2 O 3 , MgO, AlN as well as rare earth oxides have been used as sintering additives for silicon nitride.…”

“…Al 2 O 3 , Y 2 O 3 , MgO, AlN as well as rare earth oxides have been used as sintering additives for silicon nitride. Al 2 O 3 and Y 2 O 3 are considered the most common sintering additives but Y 2 O 3 is expensive [13,15,23,28,[38][39][40][41][42]. Fisher et al [14] reported that an alternative cheaper sintering additive would help to reduce the cost of producing Si 3 N 4 ceramics.…”