The effect of multiple factors on the synthesis of mullite whiskers based on the S-L-S mechanism and the comparison of strengthening performance
Nan Yang, Ruoyu Zhang, Qin Tian, Yuqing Zhang, Xuemin Wei, Ziqing Wang, Zhaojie Feng, Mingchao Wang
Abstract
s Mullite whiskers were synthesized based on the S-L-S growth mechanism at high temperatures using nano-alumina sol and nano-silica sol as the main materials and ammonium molybdate tetrahydrate as an additive. The effects of the silica-aluminum ratio, addition of ammonium molybdate catalyst, sintering temperature , and sintering time on the generation of mullite whiskers were systematically investigated to determine the optimal synthesis conditions. It was shown that the best raw material formulation was (3Al 2 O 3 ·2.2SiO 2 ) 8 (MoO 3 ) 2 , which minimized the mass loss of precursor powder at 0–1200°C, with only 23.62%. The mullite whiskers generated by sintering for 1–3 h maintained good microforms without agglomeration. The optimal growth conditions were 1300°C sintering for 1 h. The resulting mullite whiskers grew along the [240] direction and had the largest aspect ratios up to 10.2–14.3. The highest generation rate was up to 94.5 wt% with a grain size of 81.6 nm. The BET surface area was 2.308 m 2 /g and the pore size was 5.44 nm. The mass loss at 0–1200°C was the least, only 1.32%, with good thermal stability . In addition, the effects of (xAl 2 O 3 ·ySiO 2 ) 8 (MoO 3 ) 2 (x:y=3:1.8, 3:2, 3:2.2) whiskers treated at 1300°C on the APSB adhesive and MSABS adhesive bonding were investigated in this paper, it was clear that whiskers with x:y=3:2.2 had the best enhancement effect. For APSB adhesive strength could be increased by up to 55% and the fracture displacement by 2.42 times. For MSABS adhesives, the strength could be increased by up to 47% and the fracture displacement by 1.49 times.