Effects of in situ synthesis of CNTs/SiC_w on microstructure and properties of Al₂O₃–SiC–C composites

Abstract

Al 2 O 3 -SiC-C composites were prepared using tabular corundum, ball pitch and silicon carbide as the main raw materials. The carbon nanotubes (CNTs) and SiC whiskers (SiC w ) were in situ synthesized and their effects on the thermo-mechanical properties of Al 2 O 3 -SiC-C composites have been studied. The experimental results indicated that the high yield of SiC w and CNTs with large aspect ratio could be obtained due to addition of Ni(NO 3 ) 2 ·6H 2 O as catalyst in the composites. The cold modulus of rupture values were increased by 24% to 7.2 MPa, and the flexural modulus was increased from 19 GPa to 24 GPa. Additionally, the hot modulus of rupture reached a maximum value of 3.6 MPa, which presented a 71% increase over that of composites without catalyst. After three thermal shock cycles, the residual cold crush strength was improved from 57.1% to 76.9%. It is believed that the enhancement in the thermo-mechanical properties of Al 2 O 3 -SiC-C composites could be attributed to the reinforcement effect of SiC w and CNTs.

Effect of aggregate type on the mechanical properties and slag resistance of Al2O3‐SiC‐C hot metal ladle bricks

“…1 The required mechanical properties and slag resistance of Al 2 O 3 -SiC-C bricks used in hot metal ladles have become increasingly stringent, owing to advances in hot metal pretreatment technology that aggravate slag corrosion and the mechanical damage caused by hot metal flow during hot metal pretreatment. 2 To this end, many scholars have studied the types of carbon materials 3,4 and SiC particle size [5][6][7] in the matrix and introduced a series of additives 8,9 into the material to form a relatively complete system. As aggregates are the "skeleton" of refractory materials, differences in aggregate chemical composition and microstructure will directly affect the refractory performance and service life.…”

“…To this end, many scholars have studied the types of carbon materials 3,4 and SiC particle size 5–7 in the matrix and introduced a series of additives 8,9 into the material to form a relatively complete system. As aggregates are the “skeleton” of refractory materials, differences in aggregate chemical composition and microstructure will directly affect the refractory performance and service life.…”

Effect of in-situ carbon containing calcium aluminate cement on properties of Al2O3-SiC-C based trough castables

“…More importantly, owning to the particle sizes of graphite flakes (including modified graphite), and the non-hydrophilic property of graphitic carbon spheres, it is difficult for these carbon materials to be uniformly dispersed in castable matrices, which are crucial for the corrosion resistance of castables [17,18]. Recently, the modification of refractory matrixes by in-situ carbon composites has gained popularity [19][20][21][22]. The present authors synthesized insitu carbon-containing calcium aluminate cement (CCAC) with the phase composition close to that of Secar71 via the carbon bed sintering method, and found that the water dispersion and oxidation resistance of CCAC were enhanced, and that the corrosion resistance of the MgO-Al 2 O 3 castables bonded by CCAC were remarkably improved [23][24][25].…”

Improved corrosion resistance of Al2O3‐SiC‐C castables through in situ carbon containing aluminate cement as binder

“…More importantly, the improvements in corrosion resistance of the castables conferred by these technologies are limited because the carbon materials incorporated into the castables are difficult to be uniformly distributed in the castable matrices, which is crucial for corrosion resistance of castables, due to the particle sizes of graphite and modified graphite and the nonhydrophilic property of graphitic carbon spheres. Recently, according to Gong and co‐authors, carbon nanotubes (CNTs)/SiC whiskers were grown in situ in the Al 2 O 3 ‐SiC‐C composites with ball pitch as carbon source under the catalytic effect of Ni(NO 3 ) 2 ·6H 2 O. The mechanical properties of the Al 2 O 3 ‐SiC‐C materials were obviously improved due to the reinforced effect of in situ CNTs; the residual cold crush strength after three thermal shock cycles was improved from 57.1% to 76.9%.…”