2018 Volume 59 Issue 2 Pages 280-289
Fe(NO3)3/TEOS (tetraethoxysilane, Si(OC2H5)4)) and Fe(NO3)3/boehmite catalyst sol-gels combined with different chemical vapor deposition (CVD) growing/calcining processes were individually adopted to fabricate different carbon nanotube (CNT) composite powders and make different CNT/silica and CNT/alumina composites. Experimental results indicate that the Fe(NO3)3/TEOS and Fe(NO3)3/boehmite catalyst sol-gels with different CVD growing/calcining processes generate different products. Among those different products, CNTs could improve the tribological performance, stabilize the friction coefficient and reduce weight losses of specimens. Furthermore, ceramic products such as cristobalite, α-Al2O3 transformed from the Fe(NO3)3/TEOS and Fe(NO3)3/boehmite catalyst sol-gels at higher calcining temperatures could increase hardness and friction coefficient of specimens, however, they also result in more fluctuant friction coefficient curves and higher weight losses. The final products from different catalyst sol-gels via the two-step growing/calcining process could provide better mechanical and tribological properties of the specimens. The weight losses of CNT contained specimens with stable phase (α-Al2O3 or cristobalite) from different catalyst sol-gels via the two-step growing/calcining process are 1/4 to 1/2 of CNT free specimens and CNT contained specimens with metastable phase (γ-Al2O3 and amorphous SiO2) via the one-step growing/calcining process, respectively.
