THE MICRO FABRICATING PROCESS AND ELECTRO- MAGNETIC PROPERTIES OF TWO KINDS OF Fe POWDERS WITH DIFFERENT GRAIN SIZES AND INTERNAL STRAINS

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1 Ý 4 Ý «Vol.4 No. Ü Ò Ý ACTA METALLURGICA SINICA Aug. pp Ð Ü Î Ý 2 Fe Å ÑÏÆË ß Ø Å «( Àº¾ºÎ Ç Õ Þ ß¼, ) Ì 2 Õ Å Å Å ² Fe ÕØÐ» ± ÅØ ÎµØ., Fe, ÅÕ Å, Å Å Fe Õ± Å «, ² h ØÐ»ºØÔÑ Fe ; ØÐ»ºĐ (t) h, Õ Õ, ; Áµ t=24 h, Fe Û», Å Ç Ì Fe. Fe º¾ Î Å Û Ã, Æµ Á È»ÏÕ ÃÛ %, Ì Û 1.5 mm º ³ db Û.2 GHz, Û ³ Û. db. É Fe, ØÐ», Î Ã, µø ÁÃ Í TB3 ÓÖ A Ó Í () THE MICRO FABRICATING PROCESS AND ELECTRO- MAGNETIC PROPERTIES OF TWO KINDS OF Fe POWDERS WITH DIFFERENT GRAIN SIZES AND INTERNAL STRAINS ZHOU Jing, WANG Wei, SUN Zhigang, GUAN Jianguo State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan Correspondent: GUAN Jianguo, professor, Tel: (027)7232, guanjg@whut.edu.cn Supported by National High Technology Research and Development Program of China (No.0AA03A9) and Young Teachers from Fok Ying Tung Education Foundation (No.49) Manuscript received 03, in revised form ABSTRACT The micro fabricating process and electromagnetic properties of two kinds of Fe powders with different grain sizes and internal strains were studied. The results show that the homemade Fe powders with smaller grain size, larger internal strain and surface roughness than the carbonyl Fe powders, evolve into big and thin Fe flakes by micro fabricating for h with the help of the process control agent (PCA). When micro fabrication for t= h, these Fe flakes will fracture and their average width will reduce due to strong internal strain. When t is further prolonged to 24 h, these Fe flakes become thinner, finally, those with larger aspect ratio and smaller width can be obtained, which show high permeability and low permittivity. The epoxy resin-based microwave absorbing materials containing such Fe flakes of % (volume fraction) exhibit a reflection loss less than db in the GHz frequency range with a minimal peak of. db, whose average thickness is 1.5 mm. KEY WORDS Fe flake, micro fabrication, electromagnetic parameter, microwave absorbing properties * ß Ö ÚÙ Ó 0AA03A9 Å Î Ý ¹ Ó 49 ÑÅ : 03, Ñ : ºÝ : µ, ß, 19 Ý, È DOI:.3724/SP.J Ï µø«æï ÆÜØÆÓÇ, Ì Æ Ü Ø Ø ¹. Ï Æ Ø² Ë, Öµ È Snoek «, ÕµØÏÐ. Walser Ú [1] Á ², Ö 1 GHz ÚÖ, ÆØ Í Ö 00

2 9 ½ Ý 4», Ï ÐÏÌ Ø µ, ÏÐ È µ 0. ÆØ«Ù ¼ [2 4] Ñ [5 7] À []. Ù ¼ ¼É, Ê «Æ µú Æ ¾. ¹, Ï Ù ¼» (t) Ø, Ø Í Ù, ÆÖÙ Ï Ð Ø» Æ Ù Đ Ä, ß³Ã [3,4]. ÜÍ«Ü Đ Ä, Þ Ü ÛÍ [9] Ê Á [] Ã É [11 13] Ú«, ß Í Ï, ÌÆÖ«Ü Đ ÄØ» «ÜÏÐ, Ì Þ Æ µ Ù. Å ¹Í 2 Ö Æ Æ Æ ³ Ø Fe ÖÙ ¼ À Ø² Ñ Ù ĐÏ Ä Ø, Ã ÆÅ µ Û ÆµÖ Æ Ø Á«Í Ø Fe, Æ ÕÍÏÐ µ Đ ÄÜ, Ù ËØ Ø. 1 ÛÂÀ ¾ Ü: Fe (Carbonyl iron powders, CI), ½É, Æ 1 5 µm; ±«Fe (Homemade iron powders, HI), ¾ ±«; ÆÇË, Ì, Ð Ø ½É. Fe Ø «ÀÜ: Å g CI, 150 ml ÆÇË (² «Ø) 1 kg Ü 5 mm ØÑ Â QHJM Å Ñ, Đ Ü 5 Hz, Ö Ù ¼³» (t) Î, Ï Ð Fe, Î ± ² h, ÕÒ Fe A.»ÜÅ, Å CI ± HI ²À¾ ÕÒ Fe B. Ã Á D/Max III A X Å (XRD) Å Fe ³ Æ, ¼» Ä:, ¾ Cu K α, Đ Ü 35 kv, Đ Ü 30 ma, 2, Ë Ü min 1. Ã S 400 Đ (SEM) Å³» «Ø Fe ³ ², ÊÁ e ruler Ë Ú SEM Ø ÆÍ. Å Fe 30% Â É Ó, ¼«Ò 7.0 mm Ö 3.0 mm ÍÑ 3.5 mm Ø. Ã ËÖ Å (VNA, Agilent N5230A) Ë Fe Ö 2 GHz ÚÖØ ÏÐ (µ r ) Æ Đ Ä (ε r ). Fe Â Ø Ø RL ÚÍ [] : RL = lg Z in Z 0 (1) Z in + Z 0 Z in = Z 0 (µ r /ε r ) 1/2 tanh (j 2πfd(µ rε r ) 1/2 ) c (2), f ÜĐÏ Ø, d Ü ØÍ, c Ü Ë, Z 0 Ü, Z in Ü Ø. 2 Û ÊÞ 2.1 È Đ 1 Ü Fe CI HI Ø XRD Å., 2 Fe Ö 2θ=44., 5.0 Æ 2.3 Ê È Í ÆØ α Fe Ø. ½ Hall Williamson, ÆÃ (D) ÆÖ (ε) Ø Ü βcos θ=2εsin θ+kλ/d( X λ=0.154 nm, k Ü Scherrer Ä, θ Ü Bragg, β Ü µ ). È βcosθ/(kλ) Ü³¼, sinθ/(kλ) ÜË¼»,» ÛÉ, Ø Ü 2ε, Ö³¼ ²Ø Ü 1/D. ÚÍÕÒ CI Æ HI Ø ε Ü 0.% Æ 0.5%, D Ü 41.4 Æ 15.0 nm. 2 Ü CI Æ HI Ø SEM., CI Ø ²,, Æ Ö 1 5 µm, Intensity, a.u. HI CI , deg Ð 1 Ï Fe CI HI XRD Fig.1 XRD patterns of raw Fe powders CI and HI Ð 2 Ï Fe CI Å HI SEM Fig.2 SEM images of raw Fe powders CI (a) and HI (b)

$2 nxot> Es v7lp 0FH t \!H CI B. {:Tx zt$n i 3 xu~0'e/ (t) t Fe A N, $N \u )T*, _K \. e/, HI B t SEM, D f U t gv 9 i 4.$

3 y (u : "LJ_LpW % r 2 Æ Fe rs.dfd}u(s 99 P C Q 4 (i 2a). HI DF & 4, N+ ( & e & x &, W! t t 9 >, t r 1.5 µm, f CI, g [ u ~, " Fe A N B t U 9. j t e/, * H (i 2b). Fe B t 9U A t 9U, Ok HI r u~ 2.2 nxot> Es v7lp 0FH t \!H CI B. {:Tx zt$n i 3 xu~0'e/ (t) t Fe A N, $N \u )T*, _K \. e/, HI B t SEM, D f U t gv 9 i 4. >, CI t g [, \ n - (O e, T X ~0/ R yo r NOSt/[, + e*t Fe 'Fu~0V, r m, DR k0 & Ce ;N, {A ' [15] l 3 t}/&d. s Fe A M B s SEM Fig.3 SEM images of Fe flakes A (a d) and B (e h) obtained by micro fabricating for t=7.5 h (a, e), h (b, f), h (c, g) and 24 h (d, h) (the irregularly shaped Fe flakes are shown in the white circles in Fig.3f)

4 970 ½ Ý 4 Width, m; aspect ratio Width, m; aspect ratio (a) Width Thickness Aspect ratio Time, h (b) Time, h Ð 4 Fe A Å B Ì Å Ì Thickness, m Thickness, m Fig.4 Curves of average width, thickness and aspect ratio of Fe flakes A (a) and B (b) vs micro fabricating time Í ØÑ Ø ÏĐ ÙËØÃ µ, Õ À []. Fe A Ø Ï t Ø Ù ; Æ Fe B Ø Ö h ÖÙ, h» Æ, Ð Ø ( 3f Ñ ). ßÇ HI ÖÙ ¼ À È Í. ß Ø Ì È Ü HI µøö Æ, ÊÐ ² Ø. t Â Ò 24 h, ÍØ Fe B Ü¼, Í Ù, Fe B Î Ã Êµ, Ì ÙÖ Ø» Å Ø Í. t h», Fe A Ø Fe B Ø, t > h», Fe A Ø Fe B Ø, ÞØ Ð¹ Ø, ß Â Ç HI ÖÙ ¼ À ² Ø Fe È Í, Æ CI ² È Í, ÅÁÍ ÅÔĐØ. 5 ÜÙ ¼³» «Ø Fe A Æ B Ø Đ Ä¾ (ε ) (f) Ø., Ï t Ø, Fe A Ø ε Ù, ÌÜ Fe Ù»Ù,» Ã Ö É ² Ö, ĐÐ µ [17]. f=2 GHz», Ï t Ø, ε 9 ¹ Ù Ò, Ù Ñ %; Æ t h», ε Ù Ò, Ù Ò 0%. ßÇ CI Ø À Ö t h Î, ß 4a Ø Í Ä (a) 0 h 7.5 h h h 24 h (b) Ð 5 Fe A Å B Ã½ (ε ) (f) Fig.5 Dependence of real part of permittvity (ε ) for Fe flakes A (a) and B (b) on frequence (f) ½Â, h» Í Ü 4.92, Æ 24 h» Í a c, CI Ö t h» Æ Æ. CI ØÆ ³ Â, ÆØ Í «ÒÂ À Î, Ñ ½ ÙÖĐ À Ò Ø ÆÅ. Å HI, Ï t Ø, ε Ù, Î «, Î Ü ¼Ù, ß Fe ( 4b) Â. Ö t= h»«ø Fe B Ø ε t= h Ø, ß ÌÜ Fe B Ö Í, «ÜÍ Fe Ø. f=2 GHz, t h», ε ² Ò, Ù 0%, Fe A Ø ε ØÙ µè 90%,» Í Æ 11.95, Fe A Ø 2.4, Ç HI CI ¹ÀØ ¼Ì, µø. t h», ε Ù Ò, Ù Ò 33%,» Í Ù Ò.5, Ç Î Ã µ. 2.3 Ò Ù ÄÔ ÜÅ Fe Ù ¼ 24 h Î«Ø Fe A Æ B ØÙ ĐÏ Ä Ø., Fe B ÜØ Đ Ä, ¾ (ε ) «ÜÑ % ( a), º (ε ) «ÜÑ 30% ( b); ÆÏÐ ¾ (µ ) Æº (µ ) ÅÁ³, ¾ Ü Ä ( c Æ d). Fe B Ø Đ Ä ÌÜ ÆÃ

5 Ý «Ù : ÄÂ ÄÔÏ ±Ö 2 Æ Fe Ö º ÐÍ 971 (a) Sample A Sample B 1.5 (b) (c) (d) Ð t=24 h ºÅ Fe A Å B Ø Î Ã Fig. Curves of real part (a) and imaginary part (b) of permittivity, real part (c) and imaginary part (d) of permeability vs frequency f for Fe flakes A and B obtained by micro fabricating for t=24 h, Ù«, ÆÐ Đ µ [3],» Fe B Ø, Ã Đ Ä«Ü. ÏÐ Ø Í Æ ÏÐ. HI µø Ö Æ, Î Æ, ³Ã ÏÐ Ø µ [9], Ì Ò Fe B Ø Í, Ï Ð ³. Ï Â Đ Â ± ¾ Ö ÚÌÊ. HI Ö ØÖ, Ä ÆÏ»ØÔ Ú, ÆÖÏ» Ø À ¹ Ò ÂĐÏ ÙË, Ï ÂÙ, Â, Fe B Ø Í, ± ¾ Í Ø Â, Í Fe A, Đ Â, ÈÖßÔ ÌÊØ²É, Ï Â ³, ² Ë Ø¾ Ü Ä [1]. È², HI ÖÙ ¼ À ØÙ ĐÏ Ù Ø Ö Ø ÆÃ ÆµØÖ Æ. ÆÅ ÚÌÊ À, ÊÕÒ Æ Ø, ÒÂ» Î, Ö Ø», Ð Ø,»Ã ÙÅÁµØ Æ Í. È CI Ü Ù ¼«Ø Fe A, HI Ü Ù ¼«Ø Fe B ÜØ Đ ÄÆ ØÏÐ, Ã, µ Ù. Reflection loss, db Sample A Sample B Ð 7 t=24 h ºÅ Fe A Å B Á µ Ø»Ï ³ Á Fig.7 Curves of reflection loss vs frequency for epoxy resin based microwave absorbing materials containing % volume fraction Fe flakes A or B obtained by micro fabricating for t=24 h (the thickness is 1.5 mm) 2.4 Õ Ù ÄÔ 7 Ü t=24 h»«ø Fe A Æ B Â ØÙ ¼ Ø Ï Ø (Fe ÄÜ %)., t=24 h»«ø Fe A, Fe B Ø ¼ Ø

6 972 ½ Ý 4 db Ø 5.9 GHz Ù Ò.2 GHz, Â.5 db «Ò. db,.7 GHz Ú Ö Ù Æ±±. Æ, ß ÎÞ ÜØ Đ Ä, ÙÅÁµÏÐ ¾ Æº, Æ Ã, µ Ù. 3 (1) Fe, ±«Fe Ø, Æ, Ö Æ. Å Ù ¼ 24 h Ù«È Í Ø Fe. Fe «Ø Fe A, ±«Fe «Ø Fe B ÙÖ«Ü Đ ÄØ», ÅÁµÏÐ. (2) ±«Fe «Ø Fe B Ø Â É¼ Ö ÄÜ %» ÊÀØ Ù. Ò Í Ü 1.5 mm», db Ø Ü.2 GHz, Ü ÂÜ. db. ÓÖ [1] Walser R M, Win W, Valanju P M. IEEE Trans Magn, 199; 34: 1390 [2] Deng L J, Zhou P H, Xie J L, Zhang L. J Appl Phys, 07; 1: 39 [3] Zhou P H, Deng L J, Xie J L, Liang D F. J Alloys Compd, 0; 44: 303 [4] Xian W, Gong R Z, Li P G, Liu L Y, Cheng W M. Mater Sci Eng, 07; 4A: 17 [5] Cho E K, Kwon H T, Cho E M, Song Y S, Sohn K Y, Park W W. Mater Sci Eng, 07; A : 3 [] Zhang B S, Lu G, Feng Y, Xiong J, Lu H X. J Magn Magn Mater, 0; 299: 5 [7] Moon B G, Sohn K Y, Park W W, Lee T D. Mater Sci Eng, 07; A : 42 [] Huang J J. PhD Thesis, Lanzhou University, 07 (. ß Ð, 07) [9] Zhang X N. PhD Thesis, Beijing Institute of Technology, 03 (Ü Þ. Æ±» ß Ð, 03) [] Nie Y, He H H, Zhao Z S, Gong R Z, Yu H B. J Magn Magn Mater, 0; 30: 5 [11] Dong D M, Guan J G, Wang W, Li W, Zhou J. Acta Metall Sin, 09; 45: 11 ( Ó,, Õ Ý, Â Ý, µ., 09; 45: 11) [] Wang Q, Guan J G, Liu S Q, Wang W, Zhang Q J. J Alloy Compd, 0; 413: 155 [13] Tong G X, Wang W, Guan J G, Zhang Q J. J Inorg Mater, 0; 21: 1 (, Õ Ý,, Ü.»Ï, 0; 21: 1) [] Fan X A, Guan J G, Li Z Z, Mou F Z, Tong G X, Wang W. J Mater Chem, ; : 7 [15] Pan J S, Tong J M, Tian M B. Material Science. th ed, Beijing: Tsinghua University Press, 199: 5 (Ð, ½,.»Ï É. Þ, Æ±: Ç µ, 199: 5) [] Chen Z H, Chen D. Mechanical Alloying and Solid Liquid Reaction Milling. 4th ed, Beijing: Chemical Industry Press, 0: 5 (Ð,. È Ð. Þ 4, Æ±:» Ç µ, 0: 5) [17] Fan X A, Guan J G, Wang W, Tong G X. J Phys, 09; 42D: 07500

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