- Email: [email protected]
carbon nanoparticles with core–shell structure synthesized by arc discharge method
Journal of Alloys and Compounds 579 (2013) 529–532
Contents lists available at SciVerse ScienceDirect
Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jalcom
Aluminum–silicon and aluminum–silicon/carbon nanoparticles with core–shell structure synthesized by arc discharge method Kelimu Tulugan a, Hyeongjo Kim a, Wonzoo Park b, YongBum Choi d, Wonjo Park c,⇑ a
Department of Energy and Mechanical, Graduation School, Gyeongsang National University, TongYong, Gyeongnam 650-160, Republic of Korea Department of Electrical Engineering, Yeungnam University, Gyeongsan, Gyeonbuk 712-749, Republic of Korea c Department of Energy and Mechanical Engineering, The Institute of Marine Industry, Gyeongsang National University, TongYong, Gyeongnam 650-160, Republic of Korea d Division of Materials and Manufacturing, Faculty of Engineering, Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima, 739-8527, Japan b
a r t i c l e
i n f o
Article history: Received 8 April 2013 Received in revised form 17 June 2013 Accepted 18 June 2013 Available online 27 June 2013 Keywords: Nanoscale compounds Oxidation Phase stability Microstructure
a b s t r a c t Al–Si and carbon coated Al–Si nanoparticles were prepared by DC arc discharge method. The morphology and chemical composition of the as prepared nanoparticles were investigated by X-ray diffraction, highresolution transmission electron microscopy (HRTEM). The Al–Si nanoparticles have a core shell structure with an Al2O3 shell around 5 nm. In the Al–Si nanoparticles there is no trace of metallic compounds, and in the carbon coated Al–Si nanoparticles, the only compounds is Al4C3. Ó 2013 Elsevier B.V. All rights reserved.
1. Introduction In recent years, the nanoparticles with shell/core structures have attracted great interests as the potential applications in lots of fields [1–4]. The outer shell can protect metallic nanoparticles against environmental degradation. In particular, the outer shells can be a component consisting of the nano-composites through the ‘‘shell/core’’ type microstructure. These excellent properties would open the ways for practical application in many fields [5]. Aluminum alloys are not only light weight materials, but also have excellent thermal conductivity, electrical conductivity, corrosion resistance, and workability. For these previous reasons, aluminum is widely used in structural components, electrical conductors, and consumer products. Among the newly developed aluminum alloys, rapidly solidified Al–Si alloys have superior mechanical properties, such as high strength, modulus, wear resistance and elevated temperature strength relative to conventional alloys [6,7]. Also Al–Si alloys are well known as typical high strength and lightweight materials, which are widely used in automotive and aerospace industries due to their higher strength; good wear resistance and low thermal expansion co-efficient [8]. ⇑ Corresponding author. Address: Department of Mechanical and Precision Engineering, Gyeongsang National University, Chundaegookchi-gil 38, Tongyeong City, Gyeongsangnam-do 650-160, Republic of Korea. Tel.: +82 55 772 9113; fax: +82 55 772 9119. E-mail address: [email protected] (W. Park). 0925-8388/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jallcom.2013.06.116
However, there was a lack of study on the nanoparticles of Al–Si system, and most of the samples were prepared by ball-milling method, with which the impurities were inevitably of the as-prepared powders. DC arc discharge has unique advantages, such as low impurity introduced into the powder, and distinct ‘‘core/shell’’ nanostructure, in this work a modified arc discharge method was employed to prepare Al–Si and carbon coated Al–Si nanoparticles. Phase structure, composition and morphology were investigated.
2. Experiment The manufacturing flow path is listed as follow: (1) Clean the inner chamber to prevent intermingling of foreign substance. (2) Set the cathode and anode materials. (3) Close the reactor and start evacuation. (4) Fill the chamber with hydrogen and argon at certain molar ratio. (5) Activate the water cooling system, then strike, stabilize the arc and move the cathode through hydraulic pressure in three dimensions. (6) Remove the cathode, shut down the power system and wait till all the nanoparticles deposits on the inner wall of the chamber. (7) Inject 5 kPa of air to form the oxide film to prevent further oxidation. (8) Standing for at least 8 h, then collect the nanoparticles from the chamber. As a raw material, Al–Si alloys bulk was first prepared by Al and Si micro size powders (>99.9% in purity) in molar ratio of 5:1. By using the arc-discharge synthesis method, the raw material bulk was mounted on the water-cooled copper electrode and served as an anode to be evaporated, meanwhile, a tungsten rod acted as the cathode. Then chamber has been evacuated, a mixture atmosphere of hydrogen and argon (1:1 in molar ratio) was then introduced to 0.04 MPa as a source of plasma and the condensing gas. As the arc was ignited between two electrodes, the alloys bulk was melted and evaporated. Finally, after passivating process, the nano sized Al–Si particles were obtained in the chamber.
530
K. Tulugan et al. / Journal of Alloys and Compounds 579 (2013) 529–532
For carbon coating, 0.76 g of glucose (C6H12O6) was dissolved in 8 ml ethylene glycol, and then dissolved glucose solution was mixed with 1 g of Al–Si nano powder. The mixture solution was dried in vacuum furnace at 150 °C for 12 h. The dried mixture was heated up to 600 °C in Ar atmosphere and kept for 0.5 h.
3. Results and discussion 3.1. Structure of Al–Si and carbon coated Al–Si Al–Si is a simple eutectic system with two solid solution phases, FCC (Al) and diamond cubic (Si), as shown in Fig. 1. The Al–Si phase diagram is a straightforward, classic example of a eutectic system where each element has little, if any solubility in the other. Aluminum melts at 660.452 °C while silicon melts at 1414 °C. (Vol. 5, No. 1, Bulletin of Alloy Phase Diagrams, 1984), shows the eutectic at 12.2 ± 0.1 at.% Si and 577 °C. The maximum solubility of Si in Al is 1.5 ± 0.1 at.% at 577 °C, and the solubility decreases to 0.05 at.% at 300 °C. There is virtually no solubility for Al in Si at any temperature to the melting point. The maximum solubility of Al in Si is 0.016 ± 0.003 at.% at the retrograde point of the Si solidus 1190 °C. Based on Fig. 1, there is only one metallic compound between Al and Si at the eutectic point, Al3Si. However, in the X-ray diffraction patterns of the Al–Si nanoparticles shown in Fig. 2, the only compound founded is in the Al–Si carbon coated system, Al4C3.
3.2. EDS results In order to confirm the composition of the nanoparticles, EDS test was conducted. Considering the EDS results, there are obvious composition deviations among the nanoparticles and their corresponding compressed master bulk. As shown in Table 1. Considering the excess of Si in the carbon coated Al–Si system, the Al and C are almost completely used to form the compound, i.e. Al4C3. In order to explain the absence of the Al3Si in the nanoparticles, taking the thermodynamic situation into consideration is necessary. Literature (Vol. 5, No. 1, Bulletin of Alloy Phase Diagrams, 1984), gives the Gibbs free energy expression in J/mol of atoms of Al3Si (G: 1242.9–2.544T, T is temperature). The temperature dependence Gibbs free energies of the Al3Si is reflected in Fig. 3. As shown in the figure, the values of the Gibbs free energy of Al3Si indicates that Al3Si’s stability is decreasing with the decreasing of the temperature, and that Al3Si is not stable at room temperature also agrees with the absence of the Al3Si.
3.3. The morphological characterization Fig. 4 shows TEM micrograph of Al–Si, Al–Si/C nanoparticles. Fig. 4A is morphology image of Al–Si nanoparticles. These particles have various dimensions with around from 50 nm to 250 nm size and the whole particle shape of Al–Si composite is that Si nanoparticles irregularly adhere around spherical Al particle surface. Fig. 4B is HRTEM image of Al–Si nano particle, this image shows that Al nano particles are covered with thin oxidation film, and present a typical core–shell structure and the shell thickness is within 5 nm, which is created for the passivating process. Fig. 4C is morphology image of Al–Si/C nanoparticles. Compared to Al–Si nanoparticles morphology, Al–Si/C particles clustered together with mass products and have irregular shapes beside Al–Si
Table 1 Characteristic of Al–Si samples. Samples
The ratio of Al to Si in the compressed bulk mixture and coating C (wt%)
The ratio of Al to Si and coating C in nanoparticles (wt%)
Al–Si Al–Si/C
83:17 47:10:43
94:6 25:72:3
Fig. 1. Al–Si phase diagram (weight percent silicon).
Fig. 2. XRD patterns of the (a) Al–Si and (b) Al–Si carbon coated nanoparticles.
Fig. 3. The Gibbs free energy versus temperature diagram of Al–Si compound (Al3Si).
K. Tulugan et al. / Journal of Alloys and Compounds 579 (2013) 529–532
531
Fig. 4. TEM micrograph of Al–Si, Al–Si/C. (A) Morphology of Al–Si nanoparticles. (B) TEM image of Al–Si nanoparticles. (C) Morphology of Al–Si/C nanoparticles, and (D) TEM image of Al–Si/C nanoparticles.
particles. Furthermore, the oxidation film is confirmed by FWEDS results which are shown in Fig. 5. The map data of the Al core–shell structure proved that the location of the O–K fits perfectly at the position of the shell part of the Al–K. Bulk Al and Si are reported to be immiscible at room temperature [9]; however, when Nanosized they can form a solid solution with the lattice parameter obeying Vegard’s law [10].
3.4. The mechanism for formation of Al–Si nanoparticles
Fig. 5. FWEDS results of the shell elements.
Gas-phase nucleation is the basis for a gas-to-particle conversion process. In this study, Al and Si were evaporated from the raw bulk with the assistance of high temperature. Large thermal gradients are created between the arc and water-cooled chamber wall. The driving forces and nucleation energy are provided by super-cooling and lead to a series of transitions, from atoms to clusters and then from clusters to nuclei [11]. Then the nuclei forms and grows by the addition of monomer units. First of all, the differences of the boiling point Al and Si (Al: 2467 °C, Si: 2900 °C), Si will firstly accomplish the transition to nuclei prior to Al, and then Al around the Si nuclei in the gas state. Secondly, the Si core will adsorb the Al atom or clusters on its surface and grow to be nanoparticles by the coagulation process. Eventually, the formation of the Al–Si nanoparticles is completed. Then, during the passivating process, the Al nanoparticles are coated with Al2O3 to protect from further oxidation at the room temperature. As for the carbon coated Al–Si, during the dried mixture was heated up to 600 °C, which is almost the melting point of Al, activated the formation of Al4C3. The maximum subcooled temperature for Al is T = 736.7 K under homogeneous nucleation and (DT/Tm)max = 0.2 (DT = Tm(931.7 K)–T). Yet in the case of most nucleation, it is heterogeneous nucleation which requires (DT/Tm)max = 0.02, so T = 913.4 K. When the subcooled temperature of Al under heterogeneous nucleation is applied on Si (Tm = 1687 K), (DT/Tm)max = 0.46 which indicates the temperature is already too low and the flowability of the Si is severely affected. It explains the absence of the Al3Si. Furthermore, that the Al–Si phase diagram is a straightforward, classic example of a eutectic system where each element has little, if any solubility in the other also favors the absence of the Al3Si.
532
K. Tulugan et al. / Journal of Alloys and Compounds 579 (2013) 529–532
4. Conclusion
References
Al–Si nanoparticles are prepared by DC arc discharge method using micro-sized powers as the raw materials. Al–Si nanoparticles have core shell structure with an Al2O3 shell of 5 nm in thickness, and the core is consisting of Al connecting with wire shaped and amorphous Si nanoparticles. As with the carbon coated Al–Si nanoparticles, the Al2O3 shell is pulverized by the coated carbon and form the Al4C3. And according to the XRD, EDS and Gibbs free energy, there is no compound between Al and Si at room temperature.
[1] T. Yogi, T.A. Nguyen, IEEE Trans. Magn. 29 (1993) 307. [2] J.J. Delaunay, T. Hayashi, M. Tomita, S. Hirono, S. Umemura, Appl. Phys. Lett. 71 (1997) 3427. [3] D.H. Reich, M. Tanase, A. Hultgren, L.A. Bauer, C.S. Chen, G.J. Meyer, J. Appl. Phys. 93 (2003) 7275. [4] X.F. Zhang, X.L. Dong, H. Huang, Y.Y. Liu, W.N. Wang, X.G. Zhu, B. Lv, J.P. Lei, C.G. Lee, Appl. Phys. Lett. 89 (2006) 053115. [5] X.F. Zhang, X.L. Dong, H. Huang, B. Lv, X.G. Zhu, J.P. Lei, S. Ma, Z.D. Zhang, J. Mater. Sci. Eng., A 454–455 (2007) 211–215. [6] N.S. Stoloff, C.T. Liu, S.C. Deevi, J. Intermetallics 8 (2000) 1313–1320. [7] M. Sayed, D. Walid, I. Ahmed, N. Erich, J. Mater. Sci. Appl. 2 (2011) 1127–1133. [8] J.P. Lei, X.L. Dong, X.G. Zhu, M.K. Lei, H. Huang, X.F. Zhang, B. Lu, W.J. Park, H.S. Chung, J. Intermetallics 15 (2007) 1589–1594. [9] H. Ye, J. Mater. Eng. Perform. 12 (3) (2003) 288. [10] J. Milligan, R. Vintila, M. Brochu, Mater. Sci. Eng. A 508 (2008) 43–49. [11] Toivo T. Kodas, J. Hampden-Smith, Aerosol Processing of Materials, John Wiley and Sons, New York, 1999.
Acknowledgements This work was supported by the Gyeongsang National University Fund for Professors on Sabbatical Leave, 2011.
Contents lists available at SciVerse ScienceDirect
Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jalcom
Aluminum–silicon and aluminum–silicon/carbon nanoparticles with core–shell structure synthesized by arc discharge method Kelimu Tulugan a, Hyeongjo Kim a, Wonzoo Park b, YongBum Choi d, Wonjo Park c,⇑ a
Department of Energy and Mechanical, Graduation School, Gyeongsang National University, TongYong, Gyeongnam 650-160, Republic of Korea Department of Electrical Engineering, Yeungnam University, Gyeongsan, Gyeonbuk 712-749, Republic of Korea c Department of Energy and Mechanical Engineering, The Institute of Marine Industry, Gyeongsang National University, TongYong, Gyeongnam 650-160, Republic of Korea d Division of Materials and Manufacturing, Faculty of Engineering, Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima, 739-8527, Japan b
a r t i c l e
i n f o
Article history: Received 8 April 2013 Received in revised form 17 June 2013 Accepted 18 June 2013 Available online 27 June 2013 Keywords: Nanoscale compounds Oxidation Phase stability Microstructure
a b s t r a c t Al–Si and carbon coated Al–Si nanoparticles were prepared by DC arc discharge method. The morphology and chemical composition of the as prepared nanoparticles were investigated by X-ray diffraction, highresolution transmission electron microscopy (HRTEM). The Al–Si nanoparticles have a core shell structure with an Al2O3 shell around 5 nm. In the Al–Si nanoparticles there is no trace of metallic compounds, and in the carbon coated Al–Si nanoparticles, the only compounds is Al4C3. Ó 2013 Elsevier B.V. All rights reserved.
1. Introduction In recent years, the nanoparticles with shell/core structures have attracted great interests as the potential applications in lots of fields [1–4]. The outer shell can protect metallic nanoparticles against environmental degradation. In particular, the outer shells can be a component consisting of the nano-composites through the ‘‘shell/core’’ type microstructure. These excellent properties would open the ways for practical application in many fields [5]. Aluminum alloys are not only light weight materials, but also have excellent thermal conductivity, electrical conductivity, corrosion resistance, and workability. For these previous reasons, aluminum is widely used in structural components, electrical conductors, and consumer products. Among the newly developed aluminum alloys, rapidly solidified Al–Si alloys have superior mechanical properties, such as high strength, modulus, wear resistance and elevated temperature strength relative to conventional alloys [6,7]. Also Al–Si alloys are well known as typical high strength and lightweight materials, which are widely used in automotive and aerospace industries due to their higher strength; good wear resistance and low thermal expansion co-efficient [8]. ⇑ Corresponding author. Address: Department of Mechanical and Precision Engineering, Gyeongsang National University, Chundaegookchi-gil 38, Tongyeong City, Gyeongsangnam-do 650-160, Republic of Korea. Tel.: +82 55 772 9113; fax: +82 55 772 9119. E-mail address: [email protected] (W. Park). 0925-8388/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jallcom.2013.06.116
However, there was a lack of study on the nanoparticles of Al–Si system, and most of the samples were prepared by ball-milling method, with which the impurities were inevitably of the as-prepared powders. DC arc discharge has unique advantages, such as low impurity introduced into the powder, and distinct ‘‘core/shell’’ nanostructure, in this work a modified arc discharge method was employed to prepare Al–Si and carbon coated Al–Si nanoparticles. Phase structure, composition and morphology were investigated.
2. Experiment The manufacturing flow path is listed as follow: (1) Clean the inner chamber to prevent intermingling of foreign substance. (2) Set the cathode and anode materials. (3) Close the reactor and start evacuation. (4) Fill the chamber with hydrogen and argon at certain molar ratio. (5) Activate the water cooling system, then strike, stabilize the arc and move the cathode through hydraulic pressure in three dimensions. (6) Remove the cathode, shut down the power system and wait till all the nanoparticles deposits on the inner wall of the chamber. (7) Inject 5 kPa of air to form the oxide film to prevent further oxidation. (8) Standing for at least 8 h, then collect the nanoparticles from the chamber. As a raw material, Al–Si alloys bulk was first prepared by Al and Si micro size powders (>99.9% in purity) in molar ratio of 5:1. By using the arc-discharge synthesis method, the raw material bulk was mounted on the water-cooled copper electrode and served as an anode to be evaporated, meanwhile, a tungsten rod acted as the cathode. Then chamber has been evacuated, a mixture atmosphere of hydrogen and argon (1:1 in molar ratio) was then introduced to 0.04 MPa as a source of plasma and the condensing gas. As the arc was ignited between two electrodes, the alloys bulk was melted and evaporated. Finally, after passivating process, the nano sized Al–Si particles were obtained in the chamber.
530
K. Tulugan et al. / Journal of Alloys and Compounds 579 (2013) 529–532
For carbon coating, 0.76 g of glucose (C6H12O6) was dissolved in 8 ml ethylene glycol, and then dissolved glucose solution was mixed with 1 g of Al–Si nano powder. The mixture solution was dried in vacuum furnace at 150 °C for 12 h. The dried mixture was heated up to 600 °C in Ar atmosphere and kept for 0.5 h.
3. Results and discussion 3.1. Structure of Al–Si and carbon coated Al–Si Al–Si is a simple eutectic system with two solid solution phases, FCC (Al) and diamond cubic (Si), as shown in Fig. 1. The Al–Si phase diagram is a straightforward, classic example of a eutectic system where each element has little, if any solubility in the other. Aluminum melts at 660.452 °C while silicon melts at 1414 °C. (Vol. 5, No. 1, Bulletin of Alloy Phase Diagrams, 1984), shows the eutectic at 12.2 ± 0.1 at.% Si and 577 °C. The maximum solubility of Si in Al is 1.5 ± 0.1 at.% at 577 °C, and the solubility decreases to 0.05 at.% at 300 °C. There is virtually no solubility for Al in Si at any temperature to the melting point. The maximum solubility of Al in Si is 0.016 ± 0.003 at.% at the retrograde point of the Si solidus 1190 °C. Based on Fig. 1, there is only one metallic compound between Al and Si at the eutectic point, Al3Si. However, in the X-ray diffraction patterns of the Al–Si nanoparticles shown in Fig. 2, the only compound founded is in the Al–Si carbon coated system, Al4C3.
3.2. EDS results In order to confirm the composition of the nanoparticles, EDS test was conducted. Considering the EDS results, there are obvious composition deviations among the nanoparticles and their corresponding compressed master bulk. As shown in Table 1. Considering the excess of Si in the carbon coated Al–Si system, the Al and C are almost completely used to form the compound, i.e. Al4C3. In order to explain the absence of the Al3Si in the nanoparticles, taking the thermodynamic situation into consideration is necessary. Literature (Vol. 5, No. 1, Bulletin of Alloy Phase Diagrams, 1984), gives the Gibbs free energy expression in J/mol of atoms of Al3Si (G: 1242.9–2.544T, T is temperature). The temperature dependence Gibbs free energies of the Al3Si is reflected in Fig. 3. As shown in the figure, the values of the Gibbs free energy of Al3Si indicates that Al3Si’s stability is decreasing with the decreasing of the temperature, and that Al3Si is not stable at room temperature also agrees with the absence of the Al3Si.
3.3. The morphological characterization Fig. 4 shows TEM micrograph of Al–Si, Al–Si/C nanoparticles. Fig. 4A is morphology image of Al–Si nanoparticles. These particles have various dimensions with around from 50 nm to 250 nm size and the whole particle shape of Al–Si composite is that Si nanoparticles irregularly adhere around spherical Al particle surface. Fig. 4B is HRTEM image of Al–Si nano particle, this image shows that Al nano particles are covered with thin oxidation film, and present a typical core–shell structure and the shell thickness is within 5 nm, which is created for the passivating process. Fig. 4C is morphology image of Al–Si/C nanoparticles. Compared to Al–Si nanoparticles morphology, Al–Si/C particles clustered together with mass products and have irregular shapes beside Al–Si
Table 1 Characteristic of Al–Si samples. Samples
The ratio of Al to Si in the compressed bulk mixture and coating C (wt%)
The ratio of Al to Si and coating C in nanoparticles (wt%)
Al–Si Al–Si/C
83:17 47:10:43
94:6 25:72:3
Fig. 1. Al–Si phase diagram (weight percent silicon).
Fig. 2. XRD patterns of the (a) Al–Si and (b) Al–Si carbon coated nanoparticles.
Fig. 3. The Gibbs free energy versus temperature diagram of Al–Si compound (Al3Si).
K. Tulugan et al. / Journal of Alloys and Compounds 579 (2013) 529–532
531
Fig. 4. TEM micrograph of Al–Si, Al–Si/C. (A) Morphology of Al–Si nanoparticles. (B) TEM image of Al–Si nanoparticles. (C) Morphology of Al–Si/C nanoparticles, and (D) TEM image of Al–Si/C nanoparticles.
particles. Furthermore, the oxidation film is confirmed by FWEDS results which are shown in Fig. 5. The map data of the Al core–shell structure proved that the location of the O–K fits perfectly at the position of the shell part of the Al–K. Bulk Al and Si are reported to be immiscible at room temperature [9]; however, when Nanosized they can form a solid solution with the lattice parameter obeying Vegard’s law [10].
3.4. The mechanism for formation of Al–Si nanoparticles
Fig. 5. FWEDS results of the shell elements.
Gas-phase nucleation is the basis for a gas-to-particle conversion process. In this study, Al and Si were evaporated from the raw bulk with the assistance of high temperature. Large thermal gradients are created between the arc and water-cooled chamber wall. The driving forces and nucleation energy are provided by super-cooling and lead to a series of transitions, from atoms to clusters and then from clusters to nuclei [11]. Then the nuclei forms and grows by the addition of monomer units. First of all, the differences of the boiling point Al and Si (Al: 2467 °C, Si: 2900 °C), Si will firstly accomplish the transition to nuclei prior to Al, and then Al around the Si nuclei in the gas state. Secondly, the Si core will adsorb the Al atom or clusters on its surface and grow to be nanoparticles by the coagulation process. Eventually, the formation of the Al–Si nanoparticles is completed. Then, during the passivating process, the Al nanoparticles are coated with Al2O3 to protect from further oxidation at the room temperature. As for the carbon coated Al–Si, during the dried mixture was heated up to 600 °C, which is almost the melting point of Al, activated the formation of Al4C3. The maximum subcooled temperature for Al is T = 736.7 K under homogeneous nucleation and (DT/Tm)max = 0.2 (DT = Tm(931.7 K)–T). Yet in the case of most nucleation, it is heterogeneous nucleation which requires (DT/Tm)max = 0.02, so T = 913.4 K. When the subcooled temperature of Al under heterogeneous nucleation is applied on Si (Tm = 1687 K), (DT/Tm)max = 0.46 which indicates the temperature is already too low and the flowability of the Si is severely affected. It explains the absence of the Al3Si. Furthermore, that the Al–Si phase diagram is a straightforward, classic example of a eutectic system where each element has little, if any solubility in the other also favors the absence of the Al3Si.
532
K. Tulugan et al. / Journal of Alloys and Compounds 579 (2013) 529–532
4. Conclusion
References
Al–Si nanoparticles are prepared by DC arc discharge method using micro-sized powers as the raw materials. Al–Si nanoparticles have core shell structure with an Al2O3 shell of 5 nm in thickness, and the core is consisting of Al connecting with wire shaped and amorphous Si nanoparticles. As with the carbon coated Al–Si nanoparticles, the Al2O3 shell is pulverized by the coated carbon and form the Al4C3. And according to the XRD, EDS and Gibbs free energy, there is no compound between Al and Si at room temperature.
[1] T. Yogi, T.A. Nguyen, IEEE Trans. Magn. 29 (1993) 307. [2] J.J. Delaunay, T. Hayashi, M. Tomita, S. Hirono, S. Umemura, Appl. Phys. Lett. 71 (1997) 3427. [3] D.H. Reich, M. Tanase, A. Hultgren, L.A. Bauer, C.S. Chen, G.J. Meyer, J. Appl. Phys. 93 (2003) 7275. [4] X.F. Zhang, X.L. Dong, H. Huang, Y.Y. Liu, W.N. Wang, X.G. Zhu, B. Lv, J.P. Lei, C.G. Lee, Appl. Phys. Lett. 89 (2006) 053115. [5] X.F. Zhang, X.L. Dong, H. Huang, B. Lv, X.G. Zhu, J.P. Lei, S. Ma, Z.D. Zhang, J. Mater. Sci. Eng., A 454–455 (2007) 211–215. [6] N.S. Stoloff, C.T. Liu, S.C. Deevi, J. Intermetallics 8 (2000) 1313–1320. [7] M. Sayed, D. Walid, I. Ahmed, N. Erich, J. Mater. Sci. Appl. 2 (2011) 1127–1133. [8] J.P. Lei, X.L. Dong, X.G. Zhu, M.K. Lei, H. Huang, X.F. Zhang, B. Lu, W.J. Park, H.S. Chung, J. Intermetallics 15 (2007) 1589–1594. [9] H. Ye, J. Mater. Eng. Perform. 12 (3) (2003) 288. [10] J. Milligan, R. Vintila, M. Brochu, Mater. Sci. Eng. A 508 (2008) 43–49. [11] Toivo T. Kodas, J. Hampden-Smith, Aerosol Processing of Materials, John Wiley and Sons, New York, 1999.
Acknowledgements This work was supported by the Gyeongsang National University Fund for Professors on Sabbatical Leave, 2011.