- Email: [email protected]
SiC–Ti layered material prepared by binder-treated powder sintering
Journal of Materials Processing Technology 209 (2009) 4607–4610
Contents lists available at ScienceDirect
Journal of Materials Processing Technology journal homepage: www.elsevier.com/locate/jmatprotec
SiC–Ti layered material prepared by binder-treated powder sintering Yinghuan Kuang, Tungwai Leo Ngai ∗ , Huiguo Luo, Yuanyuan Li Guangdong Key Laboratory for Advanced Metallic Materials Fabrication and Forming, School of Mechanical & Automotive Engineering, South China University of Technology, China
a r t i c l e
i n f o
Article history: Keywords: SiC Ti Layered material Powder metallurgy
a b s t r a c t Ti–SiC layered material was prepared by binder-treated powder metallurgy method. Ti, SiC and C powders were ball-milled and then binder treated. Mixture of the treated powder was loaded into a stainless steel mold first and followed by loading the pure Ti powder on top of the treated powder, then compacted under a pressure of 200 MPa at 165 ◦ C with a pressing speed of 250 mm/min. The green compacts were debinded at 500 ◦ C for 1 h and sintered at 1500 ◦ C for 2 h under argon atmosphere. The sintering temperature was determined by measuring the phase formation temperatures between Ti, SiC and C powders, using differential scanning calorimetric method. The reaction products after sintering were analyzed. Microstructure of the prepared Ti–SiC layered material was also studied. © 2008 Elsevier B.V. All rights reserved.
1. Introduction Silicon carbide (SiC) is an excellent ceramic material and being used widely in high temperature structural applications and also utilized as reinforcement in materials to improve mechanical properties (Leucht and Dudek, 1994; Balig, 1994). In general, SiC needs to be joined with metals for a variety of applications (Fukai et al., 1996). Interface is one of most important issues in many of these applications, i.e., semiconductor physics and electronic device. Moreover, the performance of the composite is controlled to a large extent by the stability of the interface at high temperatures (Guo et al., 1999). Interface reactions between the matrix and the reinforcing materials may lead to structural instability and thereby deteriorate the mechanical properties of the composite. Therefore investigations of the phases formed at the metal/SiC interface and the stability of the interface at high temperatures are of great importance. In this study, Ti–SiC layered material was prepared by bindertreated powder metallurgy method. Elemental Ti, SiC and graphite powders were ball-milled and then binder treated. The interfacial reaction products were identified by X-ray diffraction (XRD). Microstructure of the prepared Ti–SiC layered material was also studied. 2. Experimental procedures Commercial titanium (purity >99.3 wt%, −300 mesh), SiC (purity >99.5 wt%, −300 mesh) and graphite (purity >99.0 wt%, −500 mesh)
∗ Corresponding author. Tel.: +86 20 87112272; fax: +86 20 87112111. E-mail addresses: [email protected] (Y. Kuang), [email protected] (T.L. Ngai). 0924-0136/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jmatprotec.2008.11.033
powders were used as starting materials with a molar ratio of 3Ti:5SiC:1C corresponding to the composition of 4SiC–Ti3 SiC2 in the end products. After pre-mixed in a V-type mixing machine for 5 h, the powder was ball-milled in a planetary mill loaded with Ø10 mm hardened stainless steel balls at a rotating speed of 240 r/min for 5, 10 and 15 h under Ar atmosphere, respectively. The charge ratio (ball to powder mass ratio) employed was 20:1. Abrasion of the balls during milling was relatively small, no iron could be detected using XRD spectrometry. Then the mixed powder was binder treated by wet mixing with 0.5 wt% of polymeric binder. After drying for 24 h in a vacuum drying chamber, the mixture was grinded and screen through a 200-mesh sieve. About 2 g of the binder-treated mix powder was put into a heated stainless steel mold at a temperature of 165 ◦ C, and then followed by loading about 2 g of titanium powder on top of the binder-treated mix powder. The compacting pressure was 200 MPa and a pressing speed of 250 mm/min was used to form a disc-shaped green compact with a diameter of 20 mm and a height of about 5 mm. The green compacts were heated to 500 ◦ C using a heating rate of 5 ◦ C/min and debinded at this temperature for 1 h, under flowing argon atmosphere. After debinding, the samples were heated to 1500 ◦ C with a heating rate of 10 ◦ C/min and kept at 1500 ◦ C for 2 h under argon atmosphere and then subsequently furnace cooled to room temperature. The phases formed after ball-milling and the phases formed in the sintered Ti–SiC layered material were analyzed by employing XRD using Co K␣ radiation. Differential scanning calorimetry (DSC) tests on the binder and also on the mixed powders were performed by using a NETZSCH STA449C thermal analysis instrument, with a heating rate of 10 ◦ C/min under flowing Ar (99.999%).
4608
Y. Kuang et al. / Journal of Materials Processing Technology 209 (2009) 4607–4610
Fig. 3. DSC curves of the mixed power of (a) Ti, C and SiC; and (b) Ti and SiC. Fig. 1. X-ray diffraction pattern (Co K␣) of ball-milled powder.
3. Results and discussion Fig. 1 shows the X-ray diffraction patterns of Ti, C and SiC mixed powder after ball-milling for 5, 10 and 15 h with a start composition of 3Ti:5SiC:1C. Trace amount of Ti3 SiC2 can be detected after 5 h of milling. Further milling leaded to the widening of the characteristic peaks, indicating finer grains was obtained. The benefit of ball-milling not only provides finer grains, but also promoted the formation of Ti3 SiC2 phase, which is beneficial to the sintering of SiC. Fig. 2 shows the DSC and thermogravinometry (TG) results of the binder (approximately 8 mg). From the DSC curve, it can be seen that main endothermic peaks appear at 170 ◦ C and at 360–460 ◦ C range, respectively. The low temperature peaks attributed to the melting of the binder, while, the high temperature peaks corresponded to the dissociation or vaporization of the binder. The TG curve clearly showed that most of the binder was being eliminated at a temperature range of 360–460 ◦ C, thus 500 ◦ C was chosen as the debinding temperature in this study. Fig. 3 shows the DSC results for (a) Ti, SiC and C mixed power with a molar ratio of 3:5:1, and also for (b) Ti and SiC mixed power with a molar ratio of 1:1. Both curves (a) and (b) in Fig. 3 show sharp exothermic peak at 1360 ◦ C indicated that there was a strong phase forming reaction took place, which corresponded to the formation of the Ti3 SiC2 phase. Although same amount of powders (about 22.3 mg) were used in both DSC tests, the peak in curve (b) (with a heat of formation of −87.3 J/g) was larger than the peak in curve a (with a heat of formation of −33.9 J/g) indicating that the reaction between Ti and SiC was stronger than the reaction between Ti, C and
Fig. 2. DSC and TG curves of the binder.
SiC. The reason for this was that part of the Ti reacted with C before reaching 1360 ◦ C and thus the amount of Ti that can reacted with the SiC was lesser when compared with those mixed powders. El-Raghy and Barsoum (1999) fabricated Ti3 SiC2 by using Ti, SiC and graphite
Fig. 4. Optical pictures of the prepared Ti–SiC layered material; (a) Ti side; (b) SiC side.
Y. Kuang et al. / Journal of Materials Processing Technology 209 (2009) 4607–4610
4609
Fig. 5. Optical micrographs of the SiC-based composite matrix.
powder, they reported that TiC was the first formed phase, then Ti5 Si3 Cx formed subsequently, and finally Ti3 SiC2 formed. Using Ti, Si and C to fabricate Ti3 SiC2 , Sato et al. (2000) revealed that TiC and Ti5 Si3 were the major phases formed in the temperature ranging from 1000 to 1300 ◦ C. The Ti5 Si3 phase disappeared after the temperature further increase, and Ti3 SiC2 started to appear at above 1300 ◦ C. Fig. 4 shows the optical pictures of the prepared Ti–SiC layered material. No surface defects can be observed on both sides of the
Fig. 7. X-ray diffraction pattern (Co K␣) (a) at the SiC matrix; (b) at the SiC matrix near the interface.
sintered materials. Fig. 5 is an optical micrograph of the SiC-based composite matrix, the dark areas were pores, the dark grey phase was SiC and the white phase was TiC with small mount of Ti3 SiC2 (light grey). Fig. 6(a) and (b) were the optical micrographs of the sintered material showing the interface between Ti and SiC at different magnification. The layered material was metallurgically bound together by a reaction layer without noticeable cracks, but some small pores can be observed at the interface. The reaction layer has a width of approximately 15 m, as shown in Fig. 6. Fig. 7(a) and (b) were the XRD results at the SiC matrix and at the SiC matrix near the interface, respectively. Fig. 7(b) reveals strong TiC and SiC peaks, with relatively faint peaks of Ti3 SiC2 , while Fig. 7(a) shows much less TiC formed. XRD results as shown in Fig. 7(b) also illustrated that the majority of the phases formed at the interface were TiC with trace amount of Ti3 SiC2 . Li et al. (2004) suggested that TiC can be formed from the decomposition of Ti3 SiC2 at high temperature (1500 ◦ C) in the presence of excess carbon. Tong et al. (1995) reported the formation of TiC as result of the decomposition of Ti3 SiC2 , when Ti3 SiC2 and SiC were being hot pressed at 1500–1600 ◦ C. Racault et al. (1994) showed that heating of Ti3 SiC2 powders in graphite crucibles at 1350 ◦ C will resulted in the formation of TiCx and SiC. Kooi et al. (1999) laser embedding SiC particles in Ti–6Al–4V results in reaction layers of TiC around SiC, and Si released during the reaction: SiC + Ti → TiC + Si Fig. 6. Optical micrographs of the interface between Ti and SiC; (a) at 500× and (b) at 1000×.
(1)
In this study, it is believed that SiC reacted with Ti at the interface and resulted in forming TiC and Si. Some of the released Si
4610
Y. Kuang et al. / Journal of Materials Processing Technology 209 (2009) 4607–4610
reacted with Ti to form TiSi2 and Ti5 Si3 . And this titanium silicide will reacted with TiC forming Ti3 SiC2 eventually. The spheroidal particles found at the interface as shown in Fig. 6(b) were obviously due to melting. All equilibrium phases that can be found in the Ti–Si–C ternary system have melting temperatures higher than 1500 ◦ C, except for Si, which has a melting point of 1414 ◦ C. Besides, there are two binary eutectics of 1330 ◦ C formed in the Ti–Si system (one at about 14 at.% Si, between Ti and Ti5 Si3 , while the other at about 84 at.% Si, between TiSi2 and Si). Therefore, spheroidal particles at the interface were probably TiSi2 and Ti5 Si3 . The amount of formed TiSi2 and Ti5 Si3 phases were trace that cannot be detected by XRD. These results also suggested that if liquid phase was not preferred during sintering, lower sintering temperature should be selected instead of 1500 ◦ C. 4. Conclusions (1) Binder-treated powder metallurgy method can be used to prepare SiC–Ti layered material. No noticeable surface defects can be observed. (2) The layered material was metallurgically bound together by a reaction layer of approximately 15 m. Majority of the formed phases founded at the interface were TiC, with trace amount of Ti3 SiC2 , TiSi2 and Ti5 Si3 . (3) The benefit of ball-milling not only provides finer powder particles and grains, but also promoted the formation of Ti3 SiC2 phase, which is beneficial to the sintering of SiC. Trace amount of Ti3 SiC2 can be detected after 5 h of milling. No new phase formed with the increasing of milling time, only finer particles were obtained. (4) Sintering temperature of 1500 ◦ C was used in this study. At this temperature, liquid phase will be formed, although only
negligible amount of liquid was involved, lower sintering temperature should be selected if liquid phase are not preferred during sintering. Acknowledgement This work was supported by the National Natural Science Foundation of China (NSFC) under Grant No. 50774036 and also by Guangdong Provincial Natural Science Foundation under Grant No. 8151064101000029. References Balig, B.J., 1994. Power semiconductor devices for variable-frequency drives. Proc. IEEE 82, 1112–1122. El-Raghy, T., Barsoum, M.W., 1999. Processing and mechanical properties of Ti3 SiC2 . I. Reaction path and microstructure evolution. J. Am. Ceram. Soc. 82, 2849–2954. Fukai, T., Naka, M., Schuster, J.C., 1996. Bonding and interfacial structures of SiC/Zr joints. Trans. JWRI 25 (1), 59–62. Guo, S.Q., Kagawa, Y., Fukushima, A., Fujiwara, C., 1999. Interface characterization of metal-coated SiC fibre-reinforced Ti-15-3 matrix composites. Metall. Mater. Trans. A 30, 653–666. Kooi, B.J., Kabel, M., Kloosterman, A.B., Hosson, J.Th.M.De., 1999. Reaction layers around SiC particles in Ti: an electron microscopy study. Acta Mater. 47, 3105–3116. Leucht, R., Dudek, H.J., 1994. Properties of SiC fibre reinforced titanium alloy processed by fibre coating and hot isostatic pressing. Mater. Sci. Eng. A 188, 201–210. Li, S.B., Xie, J.X., Zhang, L.T., Chang, L.F., 2004. In situ synthesis of Ti3 SiC2 /SiC composite by displacement reaction of Si and TiC. Mater. Sci. Eng. A 381, 51–56. Racault, C., Langlais, F., Naslain, R., 1994. Solid-state synthesis and characterization of the ternary phase Ti3 SiC2 . J. Mater. Sci. 29, 3384–3392. Sato, F., Li, J.F., Watanabe, R., 2000. Reaction synthesis of Ti3 SiC2 from mixture of elemental powders. Mater. Trans. JIM 41, 605–608. Tong, X.H., Okano, T., Iseki, T., Yano, T., 1995. Synthesis and high temperature mechanical properties of Ti3 SiC2 /SiC composite. J. Mater. Sci. 30, 3087–3090.
Contents lists available at ScienceDirect
Journal of Materials Processing Technology journal homepage: www.elsevier.com/locate/jmatprotec
SiC–Ti layered material prepared by binder-treated powder sintering Yinghuan Kuang, Tungwai Leo Ngai ∗ , Huiguo Luo, Yuanyuan Li Guangdong Key Laboratory for Advanced Metallic Materials Fabrication and Forming, School of Mechanical & Automotive Engineering, South China University of Technology, China
a r t i c l e
i n f o
Article history: Keywords: SiC Ti Layered material Powder metallurgy
a b s t r a c t Ti–SiC layered material was prepared by binder-treated powder metallurgy method. Ti, SiC and C powders were ball-milled and then binder treated. Mixture of the treated powder was loaded into a stainless steel mold first and followed by loading the pure Ti powder on top of the treated powder, then compacted under a pressure of 200 MPa at 165 ◦ C with a pressing speed of 250 mm/min. The green compacts were debinded at 500 ◦ C for 1 h and sintered at 1500 ◦ C for 2 h under argon atmosphere. The sintering temperature was determined by measuring the phase formation temperatures between Ti, SiC and C powders, using differential scanning calorimetric method. The reaction products after sintering were analyzed. Microstructure of the prepared Ti–SiC layered material was also studied. © 2008 Elsevier B.V. All rights reserved.
1. Introduction Silicon carbide (SiC) is an excellent ceramic material and being used widely in high temperature structural applications and also utilized as reinforcement in materials to improve mechanical properties (Leucht and Dudek, 1994; Balig, 1994). In general, SiC needs to be joined with metals for a variety of applications (Fukai et al., 1996). Interface is one of most important issues in many of these applications, i.e., semiconductor physics and electronic device. Moreover, the performance of the composite is controlled to a large extent by the stability of the interface at high temperatures (Guo et al., 1999). Interface reactions between the matrix and the reinforcing materials may lead to structural instability and thereby deteriorate the mechanical properties of the composite. Therefore investigations of the phases formed at the metal/SiC interface and the stability of the interface at high temperatures are of great importance. In this study, Ti–SiC layered material was prepared by bindertreated powder metallurgy method. Elemental Ti, SiC and graphite powders were ball-milled and then binder treated. The interfacial reaction products were identified by X-ray diffraction (XRD). Microstructure of the prepared Ti–SiC layered material was also studied. 2. Experimental procedures Commercial titanium (purity >99.3 wt%, −300 mesh), SiC (purity >99.5 wt%, −300 mesh) and graphite (purity >99.0 wt%, −500 mesh)
∗ Corresponding author. Tel.: +86 20 87112272; fax: +86 20 87112111. E-mail addresses: [email protected] (Y. Kuang), [email protected] (T.L. Ngai). 0924-0136/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jmatprotec.2008.11.033
powders were used as starting materials with a molar ratio of 3Ti:5SiC:1C corresponding to the composition of 4SiC–Ti3 SiC2 in the end products. After pre-mixed in a V-type mixing machine for 5 h, the powder was ball-milled in a planetary mill loaded with Ø10 mm hardened stainless steel balls at a rotating speed of 240 r/min for 5, 10 and 15 h under Ar atmosphere, respectively. The charge ratio (ball to powder mass ratio) employed was 20:1. Abrasion of the balls during milling was relatively small, no iron could be detected using XRD spectrometry. Then the mixed powder was binder treated by wet mixing with 0.5 wt% of polymeric binder. After drying for 24 h in a vacuum drying chamber, the mixture was grinded and screen through a 200-mesh sieve. About 2 g of the binder-treated mix powder was put into a heated stainless steel mold at a temperature of 165 ◦ C, and then followed by loading about 2 g of titanium powder on top of the binder-treated mix powder. The compacting pressure was 200 MPa and a pressing speed of 250 mm/min was used to form a disc-shaped green compact with a diameter of 20 mm and a height of about 5 mm. The green compacts were heated to 500 ◦ C using a heating rate of 5 ◦ C/min and debinded at this temperature for 1 h, under flowing argon atmosphere. After debinding, the samples were heated to 1500 ◦ C with a heating rate of 10 ◦ C/min and kept at 1500 ◦ C for 2 h under argon atmosphere and then subsequently furnace cooled to room temperature. The phases formed after ball-milling and the phases formed in the sintered Ti–SiC layered material were analyzed by employing XRD using Co K␣ radiation. Differential scanning calorimetry (DSC) tests on the binder and also on the mixed powders were performed by using a NETZSCH STA449C thermal analysis instrument, with a heating rate of 10 ◦ C/min under flowing Ar (99.999%).
4608
Y. Kuang et al. / Journal of Materials Processing Technology 209 (2009) 4607–4610
Fig. 3. DSC curves of the mixed power of (a) Ti, C and SiC; and (b) Ti and SiC. Fig. 1. X-ray diffraction pattern (Co K␣) of ball-milled powder.
3. Results and discussion Fig. 1 shows the X-ray diffraction patterns of Ti, C and SiC mixed powder after ball-milling for 5, 10 and 15 h with a start composition of 3Ti:5SiC:1C. Trace amount of Ti3 SiC2 can be detected after 5 h of milling. Further milling leaded to the widening of the characteristic peaks, indicating finer grains was obtained. The benefit of ball-milling not only provides finer grains, but also promoted the formation of Ti3 SiC2 phase, which is beneficial to the sintering of SiC. Fig. 2 shows the DSC and thermogravinometry (TG) results of the binder (approximately 8 mg). From the DSC curve, it can be seen that main endothermic peaks appear at 170 ◦ C and at 360–460 ◦ C range, respectively. The low temperature peaks attributed to the melting of the binder, while, the high temperature peaks corresponded to the dissociation or vaporization of the binder. The TG curve clearly showed that most of the binder was being eliminated at a temperature range of 360–460 ◦ C, thus 500 ◦ C was chosen as the debinding temperature in this study. Fig. 3 shows the DSC results for (a) Ti, SiC and C mixed power with a molar ratio of 3:5:1, and also for (b) Ti and SiC mixed power with a molar ratio of 1:1. Both curves (a) and (b) in Fig. 3 show sharp exothermic peak at 1360 ◦ C indicated that there was a strong phase forming reaction took place, which corresponded to the formation of the Ti3 SiC2 phase. Although same amount of powders (about 22.3 mg) were used in both DSC tests, the peak in curve (b) (with a heat of formation of −87.3 J/g) was larger than the peak in curve a (with a heat of formation of −33.9 J/g) indicating that the reaction between Ti and SiC was stronger than the reaction between Ti, C and
Fig. 2. DSC and TG curves of the binder.
SiC. The reason for this was that part of the Ti reacted with C before reaching 1360 ◦ C and thus the amount of Ti that can reacted with the SiC was lesser when compared with those mixed powders. El-Raghy and Barsoum (1999) fabricated Ti3 SiC2 by using Ti, SiC and graphite
Fig. 4. Optical pictures of the prepared Ti–SiC layered material; (a) Ti side; (b) SiC side.
Y. Kuang et al. / Journal of Materials Processing Technology 209 (2009) 4607–4610
4609
Fig. 5. Optical micrographs of the SiC-based composite matrix.
powder, they reported that TiC was the first formed phase, then Ti5 Si3 Cx formed subsequently, and finally Ti3 SiC2 formed. Using Ti, Si and C to fabricate Ti3 SiC2 , Sato et al. (2000) revealed that TiC and Ti5 Si3 were the major phases formed in the temperature ranging from 1000 to 1300 ◦ C. The Ti5 Si3 phase disappeared after the temperature further increase, and Ti3 SiC2 started to appear at above 1300 ◦ C. Fig. 4 shows the optical pictures of the prepared Ti–SiC layered material. No surface defects can be observed on both sides of the
Fig. 7. X-ray diffraction pattern (Co K␣) (a) at the SiC matrix; (b) at the SiC matrix near the interface.
sintered materials. Fig. 5 is an optical micrograph of the SiC-based composite matrix, the dark areas were pores, the dark grey phase was SiC and the white phase was TiC with small mount of Ti3 SiC2 (light grey). Fig. 6(a) and (b) were the optical micrographs of the sintered material showing the interface between Ti and SiC at different magnification. The layered material was metallurgically bound together by a reaction layer without noticeable cracks, but some small pores can be observed at the interface. The reaction layer has a width of approximately 15 m, as shown in Fig. 6. Fig. 7(a) and (b) were the XRD results at the SiC matrix and at the SiC matrix near the interface, respectively. Fig. 7(b) reveals strong TiC and SiC peaks, with relatively faint peaks of Ti3 SiC2 , while Fig. 7(a) shows much less TiC formed. XRD results as shown in Fig. 7(b) also illustrated that the majority of the phases formed at the interface were TiC with trace amount of Ti3 SiC2 . Li et al. (2004) suggested that TiC can be formed from the decomposition of Ti3 SiC2 at high temperature (1500 ◦ C) in the presence of excess carbon. Tong et al. (1995) reported the formation of TiC as result of the decomposition of Ti3 SiC2 , when Ti3 SiC2 and SiC were being hot pressed at 1500–1600 ◦ C. Racault et al. (1994) showed that heating of Ti3 SiC2 powders in graphite crucibles at 1350 ◦ C will resulted in the formation of TiCx and SiC. Kooi et al. (1999) laser embedding SiC particles in Ti–6Al–4V results in reaction layers of TiC around SiC, and Si released during the reaction: SiC + Ti → TiC + Si Fig. 6. Optical micrographs of the interface between Ti and SiC; (a) at 500× and (b) at 1000×.
(1)
In this study, it is believed that SiC reacted with Ti at the interface and resulted in forming TiC and Si. Some of the released Si
4610
Y. Kuang et al. / Journal of Materials Processing Technology 209 (2009) 4607–4610
reacted with Ti to form TiSi2 and Ti5 Si3 . And this titanium silicide will reacted with TiC forming Ti3 SiC2 eventually. The spheroidal particles found at the interface as shown in Fig. 6(b) were obviously due to melting. All equilibrium phases that can be found in the Ti–Si–C ternary system have melting temperatures higher than 1500 ◦ C, except for Si, which has a melting point of 1414 ◦ C. Besides, there are two binary eutectics of 1330 ◦ C formed in the Ti–Si system (one at about 14 at.% Si, between Ti and Ti5 Si3 , while the other at about 84 at.% Si, between TiSi2 and Si). Therefore, spheroidal particles at the interface were probably TiSi2 and Ti5 Si3 . The amount of formed TiSi2 and Ti5 Si3 phases were trace that cannot be detected by XRD. These results also suggested that if liquid phase was not preferred during sintering, lower sintering temperature should be selected instead of 1500 ◦ C. 4. Conclusions (1) Binder-treated powder metallurgy method can be used to prepare SiC–Ti layered material. No noticeable surface defects can be observed. (2) The layered material was metallurgically bound together by a reaction layer of approximately 15 m. Majority of the formed phases founded at the interface were TiC, with trace amount of Ti3 SiC2 , TiSi2 and Ti5 Si3 . (3) The benefit of ball-milling not only provides finer powder particles and grains, but also promoted the formation of Ti3 SiC2 phase, which is beneficial to the sintering of SiC. Trace amount of Ti3 SiC2 can be detected after 5 h of milling. No new phase formed with the increasing of milling time, only finer particles were obtained. (4) Sintering temperature of 1500 ◦ C was used in this study. At this temperature, liquid phase will be formed, although only
negligible amount of liquid was involved, lower sintering temperature should be selected if liquid phase are not preferred during sintering. Acknowledgement This work was supported by the National Natural Science Foundation of China (NSFC) under Grant No. 50774036 and also by Guangdong Provincial Natural Science Foundation under Grant No. 8151064101000029. References Balig, B.J., 1994. Power semiconductor devices for variable-frequency drives. Proc. IEEE 82, 1112–1122. El-Raghy, T., Barsoum, M.W., 1999. Processing and mechanical properties of Ti3 SiC2 . I. Reaction path and microstructure evolution. J. Am. Ceram. Soc. 82, 2849–2954. Fukai, T., Naka, M., Schuster, J.C., 1996. Bonding and interfacial structures of SiC/Zr joints. Trans. JWRI 25 (1), 59–62. Guo, S.Q., Kagawa, Y., Fukushima, A., Fujiwara, C., 1999. Interface characterization of metal-coated SiC fibre-reinforced Ti-15-3 matrix composites. Metall. Mater. Trans. A 30, 653–666. Kooi, B.J., Kabel, M., Kloosterman, A.B., Hosson, J.Th.M.De., 1999. Reaction layers around SiC particles in Ti: an electron microscopy study. Acta Mater. 47, 3105–3116. Leucht, R., Dudek, H.J., 1994. Properties of SiC fibre reinforced titanium alloy processed by fibre coating and hot isostatic pressing. Mater. Sci. Eng. A 188, 201–210. Li, S.B., Xie, J.X., Zhang, L.T., Chang, L.F., 2004. In situ synthesis of Ti3 SiC2 /SiC composite by displacement reaction of Si and TiC. Mater. Sci. Eng. A 381, 51–56. Racault, C., Langlais, F., Naslain, R., 1994. Solid-state synthesis and characterization of the ternary phase Ti3 SiC2 . J. Mater. Sci. 29, 3384–3392. Sato, F., Li, J.F., Watanabe, R., 2000. Reaction synthesis of Ti3 SiC2 from mixture of elemental powders. Mater. Trans. JIM 41, 605–608. Tong, X.H., Okano, T., Iseki, T., Yano, T., 1995. Synthesis and high temperature mechanical properties of Ti3 SiC2 /SiC composite. J. Mater. Sci. 30, 3087–3090.