The SiC/Al4SiC4 composites with the improved mechanical properties and thermal conductivity were fabricated by the in-situ reaction of polycarbosilane(PCS)and Al powders using spark plasma sintering.The addition of 5 ...The SiC/Al4SiC4 composites with the improved mechanical properties and thermal conductivity were fabricated by the in-situ reaction of polycarbosilane(PCS)and Al powders using spark plasma sintering.The addition of 5 wt%yttrium(Y)sintering additive was useful to obtain fully dense samples after sintering at a relatively low temperature of 1650℃,due to the formation of a liquid phase during sintering.The average particle size of the in-situ formed SiC was^300 nm.The fracture toughness(4.9 MPa·m1/2),Vickers hardness(16.3 GPa),and thermal conductivity(15.8 W/(m·K))of the SiC/Al4SiC4 composite sintered at 1650℃were significantly higher than the hardness(13.2 GPa),fracture toughness(2.16 MPa·m1/2),and thermal conductivity(7.8 W/(m·K))of the monolithic Al4SiC4 ceramics.The improved mechanical and thermal properties of the composites were attributed to the high density,fine grain size,as well as the optimized grain boundary structure of the SiC/Al4SiC4 composites.展开更多
The Al4SiC4 - Al4 O4 C composites were synthesized using 1： 6. 5：2.6 of nudar rntio of kaolinite grog powder, carbon black, and aluminum powder as basic formulation, fixing the additions f kaolinite grog powder and ...The Al4SiC4 - Al4 O4 C composites were synthesized using 1： 6. 5：2.6 of nudar rntio of kaolinite grog powder, carbon black, and aluminum powder as basic formulation, fixing the additions f kaolinite grog powder and carbon black, vauing aluminum powder addition to make its proportion from 2. 6 to 3. 9, 5. 5, 7. 0, 8. 6, and 10. 4, respectively, adding phenolic resin as binder and absolute alcohol as dispersant, m＆ing well, pressing, drying, and firing at 1 700 for 2 h in a corundum tubularfizrnace in flowing argon. The eeffect cf Al addition on phase tvmposition and mierostrture of Al4SiC4 - Al4 O4 C composites wgs investigated by DTA - TG , XRD , and SEM. The results show that：（1 ） in a certain degree, more Al4SiC4 - Al4 O4 C forms with Al powder addition increasing; （2） the formed Al4SiC4 - Al4 O4 C two morphologies, narrwly, sheet atul block, atul their panicle sizes are. 5 - 15 n and 10 -20 p.m , respectively; （3） the A1 powder htition increase ha.s little effect on the grain shape and size of Al4SiC4 - Al4 O4 C： （4） ttw formed Al4O4C mainly distributes on ttw surfctce of the AluSiC4 grains with irregular shape atut partitle size below I p,m, and some of them bond together.展开更多
Al4SiC4/Al4O4C composites were synthesized based on m （ sintered clay） ： m （ active carbon ） ： m （ aluminum powder） =39： 27. 6： 33. 4, adding TiO2 powder （ anatase type, 0. 3%, 6%, 9%, respectively）, addin...Al4SiC4/Al4O4C composites were synthesized based on m （ sintered clay） ： m （ active carbon ） ： m （ aluminum powder） =39： 27. 6： 33. 4, adding TiO2 powder （ anatase type, 0. 3%, 6%, 9%, respectively）, adding 〈 10% phenolic resin as binder, mixing well, pressing, drying, firing in a corundum tubular furnace in flowing argon at 1 300, 1 400, 1 500, 1 600 and 1 700℃ for 2 h, respectively. Effect of TiO2 addition on phase composition and microstructure of Al4SiC4/Al4O4C composites was investigated by TGA, chemical analysis, XRD and SEM. The results show that ： （ 1 ） Ti in the specimens loses a little in the process of firing, all residual TiO2 transforms into TiC when the firing temperature is below 1 300℃, and the formed TiC exists stably at 1 300 - 1 700 ℃; （2） the TiO2 addition has little effect on phase composition of composites ; however, when more than 3% of TiO2 is added, the formation temperature of Al4SiC4 and Al4O4C increases from 1 500 ℃ to 1 600℃ ; （ 3 ） with the concentration of Ti^4＋ increasing, Ti^4＋ may react easily with Al4SiC4 and Al4O4C forrning the finite substitution solid solution resulting in lattice defect, which leads to the decomposition of Al4SiC4 at 1 700℃, the formation of more Al4O4C short fiber, and the formation of flake Al2O3 layer on suorface of the specimen.展开更多
基金This study was supported by the National Natural Science Foundation of China(Grant Nos.11975296 and 51811540402)the Natural Science Foundation of Ningbo City(Grant No.2018A610001).This work was also supported by the Slovak Research and Development Agency under the contract No.APVV-SK-CN-2017-0040.Peter TATARKO gratefully acknowledges the financial support of the project APVV-17-0328.
文摘The SiC/Al4SiC4 composites with the improved mechanical properties and thermal conductivity were fabricated by the in-situ reaction of polycarbosilane(PCS)and Al powders using spark plasma sintering.The addition of 5 wt%yttrium(Y)sintering additive was useful to obtain fully dense samples after sintering at a relatively low temperature of 1650℃,due to the formation of a liquid phase during sintering.The average particle size of the in-situ formed SiC was^300 nm.The fracture toughness(4.9 MPa·m1/2),Vickers hardness(16.3 GPa),and thermal conductivity(15.8 W/(m·K))of the SiC/Al4SiC4 composite sintered at 1650℃were significantly higher than the hardness(13.2 GPa),fracture toughness(2.16 MPa·m1/2),and thermal conductivity(7.8 W/(m·K))of the monolithic Al4SiC4 ceramics.The improved mechanical and thermal properties of the composites were attributed to the high density,fine grain size,as well as the optimized grain boundary structure of the SiC/Al4SiC4 composites.
文摘The Al4SiC4 - Al4 O4 C composites were synthesized using 1： 6. 5：2.6 of nudar rntio of kaolinite grog powder, carbon black, and aluminum powder as basic formulation, fixing the additions f kaolinite grog powder and carbon black, vauing aluminum powder addition to make its proportion from 2. 6 to 3. 9, 5. 5, 7. 0, 8. 6, and 10. 4, respectively, adding phenolic resin as binder and absolute alcohol as dispersant, m＆ing well, pressing, drying, and firing at 1 700 for 2 h in a corundum tubularfizrnace in flowing argon. The eeffect cf Al addition on phase tvmposition and mierostrture of Al4SiC4 - Al4 O4 C composites wgs investigated by DTA - TG , XRD , and SEM. The results show that：（1 ） in a certain degree, more Al4SiC4 - Al4 O4 C forms with Al powder addition increasing; （2） the formed Al4SiC4 - Al4 O4 C two morphologies, narrwly, sheet atul block, atul their panicle sizes are. 5 - 15 n and 10 -20 p.m , respectively; （3） the A1 powder htition increase ha.s little effect on the grain shape and size of Al4SiC4 - Al4 O4 C： （4） ttw formed Al4O4C mainly distributes on ttw surfctce of the AluSiC4 grains with irregular shape atut partitle size below I p,m, and some of them bond together.
基金supported by the National Science Foundation of China (NSFC) under Grant No.50772079the National Basic Research Program of China Earmarked Research Grant No.2009CB626605
文摘Al4SiC4/Al4O4C composites were synthesized based on m （ sintered clay） ： m （ active carbon ） ： m （ aluminum powder） =39： 27. 6： 33. 4, adding TiO2 powder （ anatase type, 0. 3%, 6%, 9%, respectively）, adding 〈 10% phenolic resin as binder, mixing well, pressing, drying, firing in a corundum tubular furnace in flowing argon at 1 300, 1 400, 1 500, 1 600 and 1 700℃ for 2 h, respectively. Effect of TiO2 addition on phase composition and microstructure of Al4SiC4/Al4O4C composites was investigated by TGA, chemical analysis, XRD and SEM. The results show that ： （ 1 ） Ti in the specimens loses a little in the process of firing, all residual TiO2 transforms into TiC when the firing temperature is below 1 300℃, and the formed TiC exists stably at 1 300 - 1 700 ℃; （2） the TiO2 addition has little effect on phase composition of composites ; however, when more than 3% of TiO2 is added, the formation temperature of Al4SiC4 and Al4O4C increases from 1 500 ℃ to 1 600℃ ; （ 3 ） with the concentration of Ti^4＋ increasing, Ti^4＋ may react easily with Al4SiC4 and Al4O4C forrning the finite substitution solid solution resulting in lattice defect, which leads to the decomposition of Al4SiC4 at 1 700℃, the formation of more Al4O4C short fiber, and the formation of flake Al2O3 layer on suorface of the specimen.
