課程名稱︰製造原理
課程性質︰選修
課程教師︰潘永寧、廖運炫、楊申語 合開
開課學院：工學院
開課系所︰機械系
考試日期（年月日）︰2009-10-23
考試時限（分鐘）：120 min
是否需發放獎勵金：是
（如未明確表示，則不予發放）
試題 :
Manufacturing Principles
1. Describe the principles and processes of growing single crystals by the
following methods: (16%)
(a) Bridgman-Stockbarger technique
(b) Czochralski technique
2. An Al-2%Cu alloy of 10cm long is normally solidfied at R=8*10^-3 cm/s under
the conditions of no solid diffusion. The phase diagram for this alloy is cha-
racterized by Ce=33%Cu, Csm=5.65%, T(melting)=660℃, and Te=548℃.
(1) What the approximate length of the steady state in the solidified bar assu-
ming limited liquid diffusion (DL=5*10^-5 cm^2/s) and no convection? (10%)
(2) How much liquid will remain when the temperature at the solid/liquid inter-
face reaches Ts, assuming complete liquid diffusion and no convectin? (6%)
What is the length of the eutectic in the finally solidified bar? (6%)
(3) If the solidification proceeds with forced convevion so the δ=0.01cm, what
will be the length of the eutectic in the solidified bar? (8%)
(4) What thermal gradient (GL) in front of the solid/liquid interface is requi-
red in order to maintain a planar solidification fornt in question (1) while
60% of the specimen was solidified?
(5) Draw the solute concentration distribution curve in the whole alloy (both
solid and liquid) when the ingot was 50% solidified for question (1) (2) (3).
(18%)
3. The semi-solid forming (SSF) includes several different processes.
(a) Describe the difference in manufacturing processes of Rheocasting and
Thixocasting. (8%)
(b) What differences will you expect in the quality of castings made by the SSF
processes versus conventional (liquid state) casting processes? (6%)
4. How are micro-porosites and micro-segregation formed in a casting? (8%)
And, how to prevent them?(4%)
Reference equations:
(1) Cs* = k*Co*(1-fs)^(k-1)
(2) CL* = Co*[1+((1-k)/k)*e^(R/DL)x']
(3) Cs* = Co*[1-(1-k)*e^(-k*R/DL)x']
(4) Cs* = k'*Co*(1-fs)^(k'-1)
(5) k' = k/[k+(1-k)*e^-(R*δ/DL)]
(6) G/R = -mL*CL*(1-k)/DL
(7) G/R = -mL*Cs*(1-k)/(k*DL)
--
※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 140.112.245.215
※ 編輯: shizhe1216 來自: 140.112.245.215 (10/27 01:17)