Preparation of crack-free Al 2 O 3 washcoat on W-Re metallic wire by electrophoretic deposition 指導教授：王聖璋 副教授 報告人：黃俊嘉

目的 : In this work ， the coated fibres are intended crack-free and high-quality ceramic coatings on W-Re metallic wire. Try atmosphere, PH and voltage of the alumina coating effects.

Experimental methods EPD 參數 DC = 40 V W-Re ： cathode distance = 10 mm deposition time = 1 min dried at room temperature for 24 h and calcined at 800°C in gas for 3 h gas ： 5 ％氫之氬氣 PAA 4X10 -6 ml/ml AIP 0.054g γ-Al 2 O 3  -Al 2 O 3  - Al 2 O 3 5wt% vigorous stirring for 20 min ultrasonic bath for 20 min W/Re DC ＋ － EPD dried and calcined SEMOM

SuccessFailure 進度 Before Now

OM OM pictures of the surface of the Al-coated wire. Green(a 、 b and c)and calcined at 800°C in atmosphere (e 、 d and f). θ-Al 2 O 3 (a and d) 、 α-Al 2 O 3 - 大明 (b and e) 、 A16SG(c and f). (a) (b)(c) (d)(e)(f)

SEM α-Al 2 O 3 powder( 大明 ) SEM micrographs of alumina deposits calcined at 800°C in atmosphere of 5%H 2 /Ar for 3 h. The experiments were preformed at room temperature and a coating with a deposited thickness of about 600 μm.

OM α-Al 2 O 3 powder( 大明 ) OM pictures of the surface of the Al-coated wire. Green(a 、 b and c)and calcined at 800°C in atmosphere(e 、 d and f). pH2(a and d) 、 pH3(b and e) 、 pH4(c and f). Some pores or defects are found on surface. (a)(b) (c) (d) (e) (f)

OM pictures of the surface of the Al-coated wire. Green (a and b ) and sintered at 800°C in atmosphere of 5%H 2 /Ar (c and d ). Electrophoretic voltage in 20V(a and c) 、 10V(b and d). OM α-Al 2 O 3 powder( 大明 ) (a)(b) (c) (d)

SEM micrographs of alumina deposits voltage in 20V calcined at 800°C in atmosphere of 5%H 2 /Ar for 3 h. The experiments were preformed at room temperature and a coating with a deposited thickness of about 65 μm SEM α-Al 2 O 3 powder( 大明 ) in pH2

Conclusions  在使用了 γ-Al 2 O 3 、 θ-Al 2 O 3 、 α-Al 2 O 3 (A16SG 和大明 (d=100nm)) 進行實驗後， 發現 α-Al 2 O 3 成果最好，但 A16SG 的粉末必須 在酸性底下，其懸浮性才會好。  使用 α-Al 2 O 3 在 800°C 氣氛下進行燒結後，發現 大明的粉末有較好的成果，所以決定用大明進 行接下來實驗。  將大明懸浮液分散在酸性溶液 (pH2) ，並在電 壓 20V 下進行電泳，燒結後，產生較成功的鍍 膜。