Electroactively smart vibration damping suspensions of diatomite/silicone oil

A comparative study of coal fly and bottom ashes as sustainable electroactive vibration damping materials

“…This approved that CFA particles form more durable electric field induced fibril-like structures than CBA which is consistent with the dielectric properties and ER flow curves discussed above. Compared to the previously reported diatomite/SO suspension system (25% under E = 3.5 kV mm -1 ), 35CFA/SO and 35CBA/SO showed excellent recoveries [9]. Thus, coal ash suspensions have better energy storage capacity than diatomite/SO system under applied electric field.…”

“…The better elastic modulus (G' = 680 kPa) and critical stress (τ c = 128 Pa) values of 35CFA/SO than 35CBA/SO were attributed to the better electroactive properties such as electrical conductivity (σ = 1.6×10 -6 S/cm), dielectric polarizability (Δε' = 6.7), ER eff (32.8) and Fe 2 O 3 content (11.2%) than 35CBA/SO. Compared to the reported elastic moduli of clays such as montmorillonite (G' = 10 kPa) and diatomite (G' = 30 kPa), 35CFA/SO system has also shown better overall viscoelastic properties [9,72].…”

“…This is in accordance with the dielectric results obtained in our study which revealed high dielectric constant for CFA/SO system (ε ∞ ' = 2.8) than CBA/SO system (ε ∞ ' = 2.4). It is also important to mention that CFA/SO and CBA/SO suspensions have higher polar- izability (∆ε' = ε 0 '-ε ∞ ') than some clay suspension systems such as diatomite/SO [9], sepiolite/SO [71], and montmorillonite/SO [72]. This may be related to the higher content of Fe 2 O 3 , which is an excellent dielectric material [73], in CFA and CBA than in diatomite (0.48%) [9], sepiolite (0.05%) [74], and montmorillonite (3.6%) [75].…”

“…On the other hand, diatomite and kaolin dispersions have higher electric field induced yield stress values than 35CFA/SO and 35CBA/SO. This may be attributed to the higher conductivities of diatomite (10 -3 S cm -1 ) [9] and kaolin (10 -4 S cm -1 ) [79] when compared to CFA (10 -6 S cm -1 ), CBA (10 -7 S cm -1 ), sepiolite (10 -12 S cm -1 ) [80], montmorillonite (10 -10 S cm -1 ) [81], and laponite (10 -5 S cm -1 ) [82]. The 35CFA/SO suspension have had higher ER activities than Na-fluorohectorite clay (τ y = 40 Pa at E = 2.0 kV mm -1 ), which is a synthetic and charged silica-based clay material [83].…”

“…It was conducted from the studies that the yield stresses of these suspensions were found to increase as follows: for alginate, from τ y = 0.5 Pa to τ y = 90 Pa under 3.0 kV mm -1 ; for cellulose, from τ y = 1.0 Pa to τ y = 1200 Pa under 3.0 kV mm -1 ; and for chitosan, from τ y = 30 Pa to τ y = 400 Pa under 7.0 kV mm -1 . In addition, some clays such as halloysite, diatomite, bentonite, and montmorillonite were reported as ER active particles due to their dielectric and electrical properties [7][8][9][10]. The high aspect ratio and charged surfaces of clays enable them to form fibril-like structures under on-electric field due to rising stiffness and resulting in increased viscosities of suspensions.…”