- Email: [email protected]
Magnetic cluster and its applications
ARTICLE IN PRESS
Journal of Magnetism and Magnetic Materials 289 (2005) 9–12 www.elsevier.com/locate/jmmm
Magnetic cluster and its applications K. Shimadaa,, S. Shuchib, H. Kannob, Y. Wub, S. Kamiyamab a Cluster of Science and Technology, Fukushima University, 1 Kanayagawa, Fukushima 960-1296, Japan Department of Machine Intelligence and System Engineering, Faculty of System Science and Technology, Akita Prefectural University, 84-4, Aza-Ebinokuchi, Honjyo 015-0055, Japan
b
Available online 25 November 2004
Abstract We succeeded in extracting magnetic clusters from an intelligent fluid that is responsive to a magnetic field. We can freely control the scale of the magnetic cluster in the range between millimeter and micrometer, with the form remaining stable without the presence of a magnetic field. We discovered an algebraic rule governing the relation between the scale of the magnetic cluster and the strength of the applied magnetic field. We could use the behavior of the magnetic cluster in certain engineering applications. In the present paper, we introduce the effect of the magnetic cluster on damper, polishing and composite material. r 2004 Elsevier B.V. All rights reserved. Keywords: Magnetic fluid; Magnetic compound fluid (MCF); Magnetic cluster; Self-assembly; Nano-technology; Aggregation; Magnetic field; Damper; Polishing; Composite material
1. Introduction As part of the trend towards the development of nano- or micro-technology, many studies have been performed regarding the self-assembly of particles or molecules using chemical processes, electric fields, or other techniques [1,2]. In the case of clusters made of metal particles, nanometer- size clusters have been produced in a magnetic fluid [3,4], and millimeter size clusters have been produced for use as magnetic brushes in laser printers. These clusters made of millimeter- or nanometer-size clusters can be formed into stable shapes under a magnetic field. However, their applicability in other contexts is difficult due to the necessity of a
constant magnetic field. Thus, metal clusters which can maintain stable shapes without the presence of a magnetic field, and which can be formed on both microscopic and macroscopic scales could be applied to engineering contexts with a versatility not seen before. We have succeed in extracting magnetic clusters from a suspension or fluid, and the self-assembly of metal particles ranging from millimeter- and micrometer-size. Here, we report the successful extraction of magnetic clusters, and the creation of a system that allows the selfassembly. We also discuss various engineering applications utilizing the magnetic clusters.
2. Magnetic cluster Corresponding author. Department of Industrial System,
Faculty of Symbiotic Systems Science, Fukushima University, 1 Kanayagawa, Fukushima 960-1296, Japan. Tel./fax: +81 24 548 5214. E-mail address: [email protected] (K. Shimada).
Magnetic clusters can be extracted from magnetorheological fluid (MR) and magnetic compound fluid (MCF), because these fluids contain comparatively large particles of micrometer order magnetic particles. A solvent is poured into the mixed fluid. The solvent is
0304-8853/$ - see front matter r 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jmmm.2004.11.004
ARTICLE IN PRESS 10
K. Shimada et al. / Journal of Magnetism and Magnetic Materials 289 (2005) 9–12
then discarded under the application of a magnetic field induced by a permanent magnet. Thus, the magnetite and iron particles cannot be drained out. This second step of pouring and discarding is repeated many times. Finally, only magnetic clusters remain in the solvent. Thus, the magnetic clusters can be extracted from the mixing suspension. Next, the suspension of magnetic clusters in the absence of a magnetic field is shaken, and the magnetic clusters are then dispersed uniformly in the suspension. When a magnetic field of a specific strength is applied to the suspension, magnetic clusters of a fixed size can be again obtained according to the intensity of the magnetic field. The statistical value has a quantitative tendency. The mean value of length and width between the ends of the clusters follow the rule of the algebraic equations shown as follows, where Hmax means the maximum magnetic field intensity when using a permanent magnet:
Fig. 2. Magnetic clusters of Fig. 1 as seen by a SEM with multiplying ratio of 5000.
Lmean ¼ 4:00 108 H 2max 9:00 105 H max þ 6:00 101 ;
ð1Þ
W mean ¼ 4:00 109 H 2max 1:00 105 H max þ 1:48 101 :
ð2Þ
Fig. 1 and 2 show an example of magnetic clusters extracted from MCF and produced under Hmax ¼ 4100 G as observed via a microscope. MCF was made carbonyl iron HQ (Yamaishi Metal Company, Japan) at 20 g and water-based magnetic fluid (MF) W35 (35 wt%, Taiho Industry Company, Japan) at 10 cm3 mixed with 1 g oleic acid Na and 14.6 g water.
Fig. 3. Schematic diagram of MCF passive damper.
3. Applications 3.1. Damper
Fig. 1. Magnetic clusters produced under a magnetic field as seen by a microscope with a multiplying ratio of 60.
We can apply the MCF involving the magnetic clusters to a cylinder-type viscous passive damper having a single degree of freedom system equipped with a spring having a spring constant k and mass m as shown in Fig. 3, that is used as an experimental apparatus. The amplitude of the given oscillation zo is 8 mm. When the outer cylinder is oscillated, the motion
ARTICLE IN PRESS K. Shimada et al. / Journal of Magnetism and Magnetic Materials 289 (2005) 9–12
11
2.50 Steady mag. (/ = 20A)
MCF (W)
m = 60.4g, k = 56.8N / m
2.00
MCF (K) MF (W)
z/z0
1.50
MF (K) MRF (W)
1.00 0.50 0.00 0.00
1.00
2.00 f/fc
3.00
4.00
Fig. 4. Frequency characteristics of amplitude ratio under the magnetic field.
of the inner cylinder is measured as z. The amplitude of the oscillation of the mass under a steady magnetic field produced by applying a given current to a electromagnet I is shown in Fig. 4, where f is the frequency, fc is the measured natural frequency, K is the kerosene base and W is the water base. The amplitude ratio of MCF decreases to a greater degree than do those of MR and MF. This is due to the formation of magnetic clusters as shown in Fig. 1.
Fig. 5. Schematic diagram of MCF float-polishing apparatus.
3.2. Polishing
40
E Ra ¼
Ranon-mag Ramag ð%Þ: Ranon-mag
with polishing pad
35 Rate of polish ERa (%)
We can also apply MCF containing magnetic clusters to polishing. We used an experimental apparatus as shown in Fig. 5. The upper and lower magnetic poles were rotated at constant speeds of 800 and 300 rpm (reverse rotation), respectively. The test specimen disk was made of SUS304 and was attached to the surface of the lower magnetic pole. The polishing pad was attached to the surface of the upper magnetic pole. MCF was inserted between the testing specimen and the polishing pad. There was a 0.1 mm clearance between the testing specimen and the polishing pad. We used kerosene-based MCF containing abrasive particles of Al2O3, and also used MF and MR having Al2O3 for the sake of comparison. After a long polishing period, the mean surface roughness Ra becomes almost constant. After about 40 min, the change ratio of surface roughness obtained by MCF and determined by Eq. (3) was compared with those obtained by MR and MF in Fig. 6. The polishing effect of MCF is larger than those of MR and MF. This is because many magnetic clusters in MCF are aligned along the magnetic field lines and the abrasive particles can polish efficiently as shown in Fig. 7. Therefore, the magnetic cluster can be effectively used for float polishing with a large clearance between the test specimen and the polishing pad:
30
MR
25
MF MCF
20 15 10 5 0 -5
0
500
1000
1500
2000
Maximum magnetic field strength Hmax (Gauss) Fig. 6. The polishing ratio in terms of magnetic field strength.
(3) Fig. 7. Magnetic cluster near the polished material surface.
ARTICLE IN PRESS 12
K. Shimada et al. / Journal of Magnetism and Magnetic Materials 289 (2005) 9–12
mental apparatus of VSM, the magnetization of the rubber along a major axis of the magnetic clusters is 8.67 emu/g and that along the minor axis 9.00 emu/g. The saturation magnetization is guessed to correspond at extreme magnetic field intensity. At our used magnetic field intensity range, the magnetization of the silicon rubber containing magnetic clusters is anisotropic due to the presence of the clusters.
4. Conclusion Fig. 8. Photograph of surface of silicon rubber.
3.3. Composite material Magnetic clusters can be contained in any material, for example, magnetic rubber. Fig. 8 shows silicon rubber having magnetic clusters produced under 1952 G of a steady magnetic field as seen via a microscope having a multiplying ratio of 378. The suspension is a mixture of HQ at 80 g, HC50 (50 wt%) at 54.96 g, kerosene at 62.4 g, and 5.7 g of silicon rubber oil including additive at 0.57 g. At a magnetic field intensity 800 kA/m that is the maximum magnetic field strength in our used experi-
Magnetic clusters can be observed in MCF and MR. The effects of these clusters can be applied to damping devices, polishing processes and magnetization, and can be obtained anistropically in the case of MCF.
References [1] M.J. Yacaman, et al., J. Vac. Sci. Technol. B 19 (4) (2001) 1091. [2] K. Kaya, J. Vacuum Soc. Jpn. 35 (8) (1992) 691. [3] T. Sawada, et al., Proc. SPIE (1999) 389. [4] E. Tulcan, V. Sofonea, J. Magn. Magn. Mater. 201 (1999) 238.
Journal of Magnetism and Magnetic Materials 289 (2005) 9–12 www.elsevier.com/locate/jmmm
Magnetic cluster and its applications K. Shimadaa,, S. Shuchib, H. Kannob, Y. Wub, S. Kamiyamab a Cluster of Science and Technology, Fukushima University, 1 Kanayagawa, Fukushima 960-1296, Japan Department of Machine Intelligence and System Engineering, Faculty of System Science and Technology, Akita Prefectural University, 84-4, Aza-Ebinokuchi, Honjyo 015-0055, Japan
b
Available online 25 November 2004
Abstract We succeeded in extracting magnetic clusters from an intelligent fluid that is responsive to a magnetic field. We can freely control the scale of the magnetic cluster in the range between millimeter and micrometer, with the form remaining stable without the presence of a magnetic field. We discovered an algebraic rule governing the relation between the scale of the magnetic cluster and the strength of the applied magnetic field. We could use the behavior of the magnetic cluster in certain engineering applications. In the present paper, we introduce the effect of the magnetic cluster on damper, polishing and composite material. r 2004 Elsevier B.V. All rights reserved. Keywords: Magnetic fluid; Magnetic compound fluid (MCF); Magnetic cluster; Self-assembly; Nano-technology; Aggregation; Magnetic field; Damper; Polishing; Composite material
1. Introduction As part of the trend towards the development of nano- or micro-technology, many studies have been performed regarding the self-assembly of particles or molecules using chemical processes, electric fields, or other techniques [1,2]. In the case of clusters made of metal particles, nanometer- size clusters have been produced in a magnetic fluid [3,4], and millimeter size clusters have been produced for use as magnetic brushes in laser printers. These clusters made of millimeter- or nanometer-size clusters can be formed into stable shapes under a magnetic field. However, their applicability in other contexts is difficult due to the necessity of a
constant magnetic field. Thus, metal clusters which can maintain stable shapes without the presence of a magnetic field, and which can be formed on both microscopic and macroscopic scales could be applied to engineering contexts with a versatility not seen before. We have succeed in extracting magnetic clusters from a suspension or fluid, and the self-assembly of metal particles ranging from millimeter- and micrometer-size. Here, we report the successful extraction of magnetic clusters, and the creation of a system that allows the selfassembly. We also discuss various engineering applications utilizing the magnetic clusters.
2. Magnetic cluster Corresponding author. Department of Industrial System,
Faculty of Symbiotic Systems Science, Fukushima University, 1 Kanayagawa, Fukushima 960-1296, Japan. Tel./fax: +81 24 548 5214. E-mail address: [email protected] (K. Shimada).
Magnetic clusters can be extracted from magnetorheological fluid (MR) and magnetic compound fluid (MCF), because these fluids contain comparatively large particles of micrometer order magnetic particles. A solvent is poured into the mixed fluid. The solvent is
0304-8853/$ - see front matter r 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jmmm.2004.11.004
ARTICLE IN PRESS 10
K. Shimada et al. / Journal of Magnetism and Magnetic Materials 289 (2005) 9–12
then discarded under the application of a magnetic field induced by a permanent magnet. Thus, the magnetite and iron particles cannot be drained out. This second step of pouring and discarding is repeated many times. Finally, only magnetic clusters remain in the solvent. Thus, the magnetic clusters can be extracted from the mixing suspension. Next, the suspension of magnetic clusters in the absence of a magnetic field is shaken, and the magnetic clusters are then dispersed uniformly in the suspension. When a magnetic field of a specific strength is applied to the suspension, magnetic clusters of a fixed size can be again obtained according to the intensity of the magnetic field. The statistical value has a quantitative tendency. The mean value of length and width between the ends of the clusters follow the rule of the algebraic equations shown as follows, where Hmax means the maximum magnetic field intensity when using a permanent magnet:
Fig. 2. Magnetic clusters of Fig. 1 as seen by a SEM with multiplying ratio of 5000.
Lmean ¼ 4:00 108 H 2max 9:00 105 H max þ 6:00 101 ;
ð1Þ
W mean ¼ 4:00 109 H 2max 1:00 105 H max þ 1:48 101 :
ð2Þ
Fig. 1 and 2 show an example of magnetic clusters extracted from MCF and produced under Hmax ¼ 4100 G as observed via a microscope. MCF was made carbonyl iron HQ (Yamaishi Metal Company, Japan) at 20 g and water-based magnetic fluid (MF) W35 (35 wt%, Taiho Industry Company, Japan) at 10 cm3 mixed with 1 g oleic acid Na and 14.6 g water.
Fig. 3. Schematic diagram of MCF passive damper.
3. Applications 3.1. Damper
Fig. 1. Magnetic clusters produced under a magnetic field as seen by a microscope with a multiplying ratio of 60.
We can apply the MCF involving the magnetic clusters to a cylinder-type viscous passive damper having a single degree of freedom system equipped with a spring having a spring constant k and mass m as shown in Fig. 3, that is used as an experimental apparatus. The amplitude of the given oscillation zo is 8 mm. When the outer cylinder is oscillated, the motion
ARTICLE IN PRESS K. Shimada et al. / Journal of Magnetism and Magnetic Materials 289 (2005) 9–12
11
2.50 Steady mag. (/ = 20A)
MCF (W)
m = 60.4g, k = 56.8N / m
2.00
MCF (K) MF (W)
z/z0
1.50
MF (K) MRF (W)
1.00 0.50 0.00 0.00
1.00
2.00 f/fc
3.00
4.00
Fig. 4. Frequency characteristics of amplitude ratio under the magnetic field.
of the inner cylinder is measured as z. The amplitude of the oscillation of the mass under a steady magnetic field produced by applying a given current to a electromagnet I is shown in Fig. 4, where f is the frequency, fc is the measured natural frequency, K is the kerosene base and W is the water base. The amplitude ratio of MCF decreases to a greater degree than do those of MR and MF. This is due to the formation of magnetic clusters as shown in Fig. 1.
Fig. 5. Schematic diagram of MCF float-polishing apparatus.
3.2. Polishing
40
E Ra ¼
Ranon-mag Ramag ð%Þ: Ranon-mag
with polishing pad
35 Rate of polish ERa (%)
We can also apply MCF containing magnetic clusters to polishing. We used an experimental apparatus as shown in Fig. 5. The upper and lower magnetic poles were rotated at constant speeds of 800 and 300 rpm (reverse rotation), respectively. The test specimen disk was made of SUS304 and was attached to the surface of the lower magnetic pole. The polishing pad was attached to the surface of the upper magnetic pole. MCF was inserted between the testing specimen and the polishing pad. There was a 0.1 mm clearance between the testing specimen and the polishing pad. We used kerosene-based MCF containing abrasive particles of Al2O3, and also used MF and MR having Al2O3 for the sake of comparison. After a long polishing period, the mean surface roughness Ra becomes almost constant. After about 40 min, the change ratio of surface roughness obtained by MCF and determined by Eq. (3) was compared with those obtained by MR and MF in Fig. 6. The polishing effect of MCF is larger than those of MR and MF. This is because many magnetic clusters in MCF are aligned along the magnetic field lines and the abrasive particles can polish efficiently as shown in Fig. 7. Therefore, the magnetic cluster can be effectively used for float polishing with a large clearance between the test specimen and the polishing pad:
30
MR
25
MF MCF
20 15 10 5 0 -5
0
500
1000
1500
2000
Maximum magnetic field strength Hmax (Gauss) Fig. 6. The polishing ratio in terms of magnetic field strength.
(3) Fig. 7. Magnetic cluster near the polished material surface.
ARTICLE IN PRESS 12
K. Shimada et al. / Journal of Magnetism and Magnetic Materials 289 (2005) 9–12
mental apparatus of VSM, the magnetization of the rubber along a major axis of the magnetic clusters is 8.67 emu/g and that along the minor axis 9.00 emu/g. The saturation magnetization is guessed to correspond at extreme magnetic field intensity. At our used magnetic field intensity range, the magnetization of the silicon rubber containing magnetic clusters is anisotropic due to the presence of the clusters.
4. Conclusion Fig. 8. Photograph of surface of silicon rubber.
3.3. Composite material Magnetic clusters can be contained in any material, for example, magnetic rubber. Fig. 8 shows silicon rubber having magnetic clusters produced under 1952 G of a steady magnetic field as seen via a microscope having a multiplying ratio of 378. The suspension is a mixture of HQ at 80 g, HC50 (50 wt%) at 54.96 g, kerosene at 62.4 g, and 5.7 g of silicon rubber oil including additive at 0.57 g. At a magnetic field intensity 800 kA/m that is the maximum magnetic field strength in our used experi-
Magnetic clusters can be observed in MCF and MR. The effects of these clusters can be applied to damping devices, polishing processes and magnetization, and can be obtained anistropically in the case of MCF.
References [1] M.J. Yacaman, et al., J. Vac. Sci. Technol. B 19 (4) (2001) 1091. [2] K. Kaya, J. Vacuum Soc. Jpn. 35 (8) (1992) 691. [3] T. Sawada, et al., Proc. SPIE (1999) 389. [4] E. Tulcan, V. Sofonea, J. Magn. Magn. Mater. 201 (1999) 238.