Spark Plasma Sintering of α/β Si3N4 Ceramics with MgO-Al2O3 and MgO-Y2O3 as Sintering Additives

The effect of Al2O3-MgO additives on the microstructure of spark plasma sintered silicon nitride

“…However, the content of the β-phase described in Ref. [4] was almost twice higher as our results. Li et al [3] studied the microstructure of silicon nitride with Al 2 O 3 -MgO and MgO-AlPO 4 obtained by SPS at 1300°C and 1400°C.…”

“…The density of the investigated ceramics also slightly increases from 3.13 g/cm 3 to 3.14 g/cm 3 (90.2% and 90.5% from the theoretical density, respectively) with an increase in the temperature of spark plasma sintering from 1550°C to 1650°C, which leads to more complete densification. The density of SPSed silicon with analogous additions described by Yu et al [4], varied from~80% to 97% depending on the sintering temperature ranged from 1400°C to 1500°C, respectively. The density of the SPSed silicon with 4 wt% MgO and 6 wt% of Al 2 O 3 described by Yan et al varied from~76% to 96% depending on the sintering temperature ranged from 1300°C to 1500°C, respectively [17].…”

“…Magnesium oxide and aluminum oxide are the most promising sintering additives because of its relatively low cost. The influence of magnesium oxide on the microstructure and mechanical properties of silicon nitride a few have been reported [2,3], but, have not been as comprehensively studied as such compositions as MgO-Y 2 O 3 , Al 2 O 3 -Y 2 O 3 [4][5][6][7]. Previous studies concerned with mostly on performing the fruitful complex of high strength and thermal stability of silicon nitride [8][9][10][11][12][13][14][15].…”

“…Relatively low sintering temperatures proposed in our study can be also justified by the fact that magnesium oxide reduces the melting point of the silicate glass on the surface of silicon nitride powder according to some Refs. [4,18].…”

Preparation and anisotropic properties of textured structural ceramics: A review

“…α-Si 3 N 4 can transfer into β-Si 3 N 4 when sintering at high temperature [207]. Some β-Si 3 N 4 seeds or rare earth oxides can decrease the activation energy of phase transformation from α-Si 3 N 4 to β-Si 3 N 4 , promoting phase transformation [208][209][210][211][212]. With some β-Si 3 N 4 seeds in α-Si 3 N 4 , the nucleation of β-Si 3 N 4 grains will take place easily at seed particle.…”