Crack Healing Behaviour and High Temperature Strength of Silicon Nitride Ceramics.

Crack‐healing and mechanical behaviour of Al2O3/SiC composites at elevated temperature

“…The sintering policies of the Al 2 O 3 /SiC are: (A) By adding 15 ∼20 mass% nanosize SiC particles to prevent the grain growth of Al 2 O 3 during sintering and increase strength similar to mullite/SiC 14–16 . (B) By adding 15–20 mass% nanosize SiC particles to induce the large self‐crack‐healing ability similar to mullite/SiC 8 , 16–19 and Si 3 N 4 /SiC 20–28 . (C) By distributing nanosize SiC particles in Al 2 O 3 grain to increase the heat‐resistance limit temperature ( T HR ) 9–12…”

“…Si 3 N 4 /SiC 20 , 22 , 27,28 and mullite/SiC 8 , 13 , 16 with very high crack‐healing ability have been developed, and several aspects of these problems have been studied systematically 16–28 . However, a systematic study has not been made completely on the above subjects of the Al 2 O 3 /SiC, yet.…”

“…[14][15][16] (B) By adding 15-20 mass% nanosize SiC particles to induce the large self-crack-healing ability similar to mullite/SiC 8,[16][17][18][19] and Si 3 N 4 /SiC. [20][21][22][23][24][25][26][27][28] (C) By distributing nanosize SiC particles in Al 2 O 3 grain to increase the heat-resistance limit temperature (T HR ). [9][10][11][12] However, if this Al 2 O 3 /SiC is to be used in structural engineering, many problems must be overcome similar to mullite/SiC and Si 3 N 4 /SiC: (1) the effect of healing conditions on the strength of the healed zone, 8,17,20,22 (2) the maximum crack size that can be healed completely, 8,21 (3) knowledge of the high-temperature strength of crackhealed zones, 17,20 (4) assessment of the cyclic-fatigue and static-fatigue strengths of a crack-healed ceramic component 18,19,22,25 and (5) whether this sample exhibits crackhealing ability during service similar to mullite/SiC 8,13 and Si 3 N 4 /SiC.…”

Crack-healing behavior and resultant strength properties of silicon carbide ceramic

“…Fig. 9 shows the effect of test temperature on the σ B of crack-healed structural ceramics developed by K. Ando et al 7,[23][24][25][26] The phase of grain boundary and crack-healed zone of Si 3 N 4 exhibited the glassy phase, thus the bending strength decreased suddenly over 1273 K. 23 On the other Fig. 9.…”

“…Therefore, the maximum crack size that can be healed completely is 2c max ≈ 50 m in surface length. The previous studies [23][24][25][26] showed that sufficient temperature and time is necessary for crack healing. However, the bending strength of specimens crack healed at 1573 K could not recovered despite increasing the holding time, as shown in Fig.…”