- Email: [email protected]
Characteristics of magnetic compound fluid (MCF) in a rotating rheometer
Journal of Magnetism and Magnetic Materials 252 (2002) 235–237
Characteristics of magnetic compound fluid (MCF) in a rotating rheometer K. Shimadaa,*, Y. Akagamib, T. Fujitac, T. Miyazakic, S. Kamiyamaa, A. Shibayamac a
Faculty of Systems Science and Technology, Akita Prefectural University, 84-4, Aza-Ebinokuchi, Honjyo 015-0055, Japan b Akita Prefectural Industrial Technology Center, 4-11 Aza-Sanuki, Arayamachi, Akita 010-1623, Japan c Akita University, 1-1 Tegatagakuenmachi, Akita 010-8502, Japan
Abstract As a new intelligent or smart fluid, we propose a magnetic compound fluid (MCF). This fluid has nm size magnetite and mm size iron particles in a solvent. The magnetic field effect on flow characteristics of MCF can demonstrate midpoint between magnetic fluid (MF) and magneto-rheological fluid (MRF). For example, the magnitude of shear stress to shear rate under a steady magnetic field in MCF can be larger than MRF by varying the compound rate of the magnetite and iron particles. This report shows an experimental data of shear stress to shear rate of MCF in rotating rheometers of cone and concentric cylinder types under transverse and longitudinal magnetic fields. r 2002 Elsevier Science B.V. All rights reserved. Keywords: Magnetic fluid; Intelligent fluid; Magneto-rheological fluid; Shear stress; Shear rate; Rotating rheometer; Magnetic field
1. Introduction The magnetic pressure and the apparent viscosity under a magnetic field of magnetic fluid (MF) is smaller than the one of magneto-rheological fluid (MRF). However, the stability of the particles distribution in a solvent of MF is better than the one of MRF. Especially, in case of higher magnetic field and mass concentration, MRF is different from MF, and MRF is appropriate to be dealt with a kind of powder rather than a fluid [1]. On the other hand, MRF has a yield. Therefore, the engineering applications are different between MF and MRF. When we consider the engineering applications, we need larger magnetic pressure and apparent viscosity under a magnetic field, and more stable distribution of particles while maintaining the behavior as a fluid.
*Corresponding author. Tel./fax: +81-184-27-2112. E-mail address: [email protected] (K. Shimada).
In the present, therefore, we propose a magnetic fluid compounded by nm-sized magnetite and mm-sized iron particles in a solvent, as a new magnetic intelligent or smart fluid. We measure the relation of shear stress to shear rate with using rotating rheometer.
2. MCF and experimental method Our proposed MCF have 10 nm magnetite coated with oleic acid and 1.2–1.6 mm iron (HQ) in a kerosene. It is compounded by MF and MRF. We examine the shear stress to shear rate with rotating rheometers of cone and concentric cylinder types under a uniform magnetic field. In the case of cone type, the magnetic field is applied transverse to the lower plate. In the case of concentric cylinder type, the magnetic fields are applied transversely and longitudinally to the cylinder axis [2]. The temperature of the fluid is constant at room temperature. We measure only MF and MRF at the same vol% of the particles in order to compare them.
0304-8853/02/$ - see front matter r 2002 Elsevier Science B.V. All rights reserved. PII: S 0 3 0 4 - 8 8 5 3 ( 0 2 ) 0 0 6 4 6 - 7
K. Shimada et al. / Journal of Magnetism and Magnetic Materials 252 (2002) 235–237
Fig. 1 shows the comparison of shear stress to shear rate curves with and without magnetic field strength. For more compound rate of iron particles, the shear stress is larger at the same magnetic field strength. Thus, the shear stress to shear rate can be varied by the compound rate of iron and magnetite particles. On the other hand, at the highest magnetic field strength, the shear stress to shear rate becomes larger non-monotonously. The cause is guessed to be due to the cluster, becoming more larger and longer with increasing magnetic field strength, as shown in Fig. 3. Fig. 2 shows the comparison of stress–strain curve according to the type of application of the magnetic field. As shown in Fig. 1(a), in case of cone type, the shear stress is constant with increasing shear rate. However, as shown in Fig. 2, it is linear to the shear rate because of the effect of shear flow. On the other hand, from Fig. 2, the shear stress to shear rate is varied by the direction of applying magnetic field. The schematic model of the aggregated particles can be guessed as shown in Fig. 3. The iron particles are aligned with connecting magnetite particles. As a result, many long chains occur. The phenomena of these clusters of chain were easily observed through microscope. The cause of experimental results in Figs. 1 and 2 are based on these aggromeration of clusters.
Fig. 4 shows the comparison of shear stress to shear rate curves due to the compound rate of magnetite and iron. By varying the compound rate, the shear rate can be increased than MRF. The cause is also due to the model of Fig. 3. Finally, as shown in Fig. 3, MCF has larger and longer chain by applying magnetic field than MF.
18
0 gauss 150 gauss 250 gauss
15 Shear stress [Pa]
3. Results and discussion
12 9 6 3 0
0
(a)
20 40 Shear rate [1/s]
60
350
0 gauss 200 gauss 400 gauss
300 Shear stress [Pa]
236
250 200 150 100 50 0
0
(b)
25
0 gauss 200 gauss 400 gauss
Shear stress [Pa]
20 15
20 40 Shear rate [1/s]
60
Fig. 2. Shear stress to shear rate curves with concentric cylinder type rheometer. Fe3O4: 26.4 vol%, HQ: 30.8 vol%. (a) Under transverse magnetic field; (b) under longitudinal magnetic field.
10 5 0
0
20 40 Shear rate [1/s]
(a)
60
Shear stress [Pa]
250
0 gauss 200 gauss 400 gauss 600 gauss 800 gauss
200 150 100 50 0 0
(b)
20 40 Shear rate [1/s]
60
Fig. 1. Shear stress to shear rate curves with cone-type rheometer: (a) Fe3O4: 26.4 vol%, HQ: 30.8 vol%; (b) Fe3O4: 8.44 vol%, HQ: 30.8 vol%.
Fig. 3. Model of particles of MCF.
K. Shimada et al. / Journal of Magnetism and Magnetic Materials 252 (2002) 235–237 2.5
0 gauss 100 gauss 200 gauss 300 gauss
Shear stress [Pa]
2
4. Conclusion
1
0
0
20
(a)
40 60 80 Shear rate [1/s]
100
120
0.09
Shear stress [Pa]
Therefore, MCF is effective in a magnetic polishing. We succeeded the clear polishing with MCF in another experimental investigation.
1.5
0.5
0 gauss 100 gauss 200 gauss 300 gauss
0.06
As a new intelligent or smart fluid, we propose a magnetic compound fluid (MCF). The tendency of shear stress to shear rate of MCF can be varied by the compound rate of magnetite and iron, the type of rotating shear flow and the direction of applying a magnetic field.
References 0.03
0
0
(b)
237
20
40 60 80 Shear rate [1/s]
100
120
Fig. 4. Shear stress to shear rate curves with concentric cylinder type rheometer under longitudinal magnetic field. (a) MCF with Fe3O4: 40.1 vol%, HQ: 2.54 vol%; (b) MRF with HQ: 2.54 vol%.
[1] G.L. Gulley, R. Tao, Proceedings of the Seventh International Conference on ERF MRS, 1999, p. 331. [2] T. Fujita, J. Mochizuki, I.J. Lin, J. Magn. Magn. Mater. 122 (1993) 29.
Characteristics of magnetic compound fluid (MCF) in a rotating rheometer K. Shimadaa,*, Y. Akagamib, T. Fujitac, T. Miyazakic, S. Kamiyamaa, A. Shibayamac a
Faculty of Systems Science and Technology, Akita Prefectural University, 84-4, Aza-Ebinokuchi, Honjyo 015-0055, Japan b Akita Prefectural Industrial Technology Center, 4-11 Aza-Sanuki, Arayamachi, Akita 010-1623, Japan c Akita University, 1-1 Tegatagakuenmachi, Akita 010-8502, Japan
Abstract As a new intelligent or smart fluid, we propose a magnetic compound fluid (MCF). This fluid has nm size magnetite and mm size iron particles in a solvent. The magnetic field effect on flow characteristics of MCF can demonstrate midpoint between magnetic fluid (MF) and magneto-rheological fluid (MRF). For example, the magnitude of shear stress to shear rate under a steady magnetic field in MCF can be larger than MRF by varying the compound rate of the magnetite and iron particles. This report shows an experimental data of shear stress to shear rate of MCF in rotating rheometers of cone and concentric cylinder types under transverse and longitudinal magnetic fields. r 2002 Elsevier Science B.V. All rights reserved. Keywords: Magnetic fluid; Intelligent fluid; Magneto-rheological fluid; Shear stress; Shear rate; Rotating rheometer; Magnetic field
1. Introduction The magnetic pressure and the apparent viscosity under a magnetic field of magnetic fluid (MF) is smaller than the one of magneto-rheological fluid (MRF). However, the stability of the particles distribution in a solvent of MF is better than the one of MRF. Especially, in case of higher magnetic field and mass concentration, MRF is different from MF, and MRF is appropriate to be dealt with a kind of powder rather than a fluid [1]. On the other hand, MRF has a yield. Therefore, the engineering applications are different between MF and MRF. When we consider the engineering applications, we need larger magnetic pressure and apparent viscosity under a magnetic field, and more stable distribution of particles while maintaining the behavior as a fluid.
*Corresponding author. Tel./fax: +81-184-27-2112. E-mail address: [email protected] (K. Shimada).
In the present, therefore, we propose a magnetic fluid compounded by nm-sized magnetite and mm-sized iron particles in a solvent, as a new magnetic intelligent or smart fluid. We measure the relation of shear stress to shear rate with using rotating rheometer.
2. MCF and experimental method Our proposed MCF have 10 nm magnetite coated with oleic acid and 1.2–1.6 mm iron (HQ) in a kerosene. It is compounded by MF and MRF. We examine the shear stress to shear rate with rotating rheometers of cone and concentric cylinder types under a uniform magnetic field. In the case of cone type, the magnetic field is applied transverse to the lower plate. In the case of concentric cylinder type, the magnetic fields are applied transversely and longitudinally to the cylinder axis [2]. The temperature of the fluid is constant at room temperature. We measure only MF and MRF at the same vol% of the particles in order to compare them.
0304-8853/02/$ - see front matter r 2002 Elsevier Science B.V. All rights reserved. PII: S 0 3 0 4 - 8 8 5 3 ( 0 2 ) 0 0 6 4 6 - 7
K. Shimada et al. / Journal of Magnetism and Magnetic Materials 252 (2002) 235–237
Fig. 1 shows the comparison of shear stress to shear rate curves with and without magnetic field strength. For more compound rate of iron particles, the shear stress is larger at the same magnetic field strength. Thus, the shear stress to shear rate can be varied by the compound rate of iron and magnetite particles. On the other hand, at the highest magnetic field strength, the shear stress to shear rate becomes larger non-monotonously. The cause is guessed to be due to the cluster, becoming more larger and longer with increasing magnetic field strength, as shown in Fig. 3. Fig. 2 shows the comparison of stress–strain curve according to the type of application of the magnetic field. As shown in Fig. 1(a), in case of cone type, the shear stress is constant with increasing shear rate. However, as shown in Fig. 2, it is linear to the shear rate because of the effect of shear flow. On the other hand, from Fig. 2, the shear stress to shear rate is varied by the direction of applying magnetic field. The schematic model of the aggregated particles can be guessed as shown in Fig. 3. The iron particles are aligned with connecting magnetite particles. As a result, many long chains occur. The phenomena of these clusters of chain were easily observed through microscope. The cause of experimental results in Figs. 1 and 2 are based on these aggromeration of clusters.
Fig. 4 shows the comparison of shear stress to shear rate curves due to the compound rate of magnetite and iron. By varying the compound rate, the shear rate can be increased than MRF. The cause is also due to the model of Fig. 3. Finally, as shown in Fig. 3, MCF has larger and longer chain by applying magnetic field than MF.
18
0 gauss 150 gauss 250 gauss
15 Shear stress [Pa]
3. Results and discussion
12 9 6 3 0
0
(a)
20 40 Shear rate [1/s]
60
350
0 gauss 200 gauss 400 gauss
300 Shear stress [Pa]
236
250 200 150 100 50 0
0
(b)
25
0 gauss 200 gauss 400 gauss
Shear stress [Pa]
20 15
20 40 Shear rate [1/s]
60
Fig. 2. Shear stress to shear rate curves with concentric cylinder type rheometer. Fe3O4: 26.4 vol%, HQ: 30.8 vol%. (a) Under transverse magnetic field; (b) under longitudinal magnetic field.
10 5 0
0
20 40 Shear rate [1/s]
(a)
60
Shear stress [Pa]
250
0 gauss 200 gauss 400 gauss 600 gauss 800 gauss
200 150 100 50 0 0
(b)
20 40 Shear rate [1/s]
60
Fig. 1. Shear stress to shear rate curves with cone-type rheometer: (a) Fe3O4: 26.4 vol%, HQ: 30.8 vol%; (b) Fe3O4: 8.44 vol%, HQ: 30.8 vol%.
Fig. 3. Model of particles of MCF.
K. Shimada et al. / Journal of Magnetism and Magnetic Materials 252 (2002) 235–237 2.5
0 gauss 100 gauss 200 gauss 300 gauss
Shear stress [Pa]
2
4. Conclusion
1
0
0
20
(a)
40 60 80 Shear rate [1/s]
100
120
0.09
Shear stress [Pa]
Therefore, MCF is effective in a magnetic polishing. We succeeded the clear polishing with MCF in another experimental investigation.
1.5
0.5
0 gauss 100 gauss 200 gauss 300 gauss
0.06
As a new intelligent or smart fluid, we propose a magnetic compound fluid (MCF). The tendency of shear stress to shear rate of MCF can be varied by the compound rate of magnetite and iron, the type of rotating shear flow and the direction of applying a magnetic field.
References 0.03
0
0
(b)
237
20
40 60 80 Shear rate [1/s]
100
120
Fig. 4. Shear stress to shear rate curves with concentric cylinder type rheometer under longitudinal magnetic field. (a) MCF with Fe3O4: 40.1 vol%, HQ: 2.54 vol%; (b) MRF with HQ: 2.54 vol%.
[1] G.L. Gulley, R. Tao, Proceedings of the Seventh International Conference on ERF MRS, 1999, p. 331. [2] T. Fujita, J. Mochizuki, I.J. Lin, J. Magn. Magn. Mater. 122 (1993) 29.