以極乾燥氮氣曝氣之鋁合金真空腔熱釋氣研究

The thermal outgassing rate of the aluminum vacuum chambers venting to extremely dry nitrogen gas

林怡君(Yi-Chun Lin)

指導教授 ： 莊克士 ； 陳俊榮

國立清華大學/原子科學院/生醫工程與環境科學系/碩士(2011年)

https://doi.org/10.6843/NTHU.2011.00289

摘要

本論文利用測量熱釋氣率以及殘留氣體分壓的方法研究酒精加工鋁合金與拋光擠型鋁合金真空腔之釋氣率行為。主要為探討釋氣率曲線斜率為-2之原理機制。實驗中以極乾燥曝氣之條件進行，希望可達到最低釋氣率值，並利用表面吸附模型計算表面吸附作用各物理參數，探討真空表面之相關狀況。
實驗結果顯示，當曝入氣體濕度條件相同的情況下(1.3ppb)，在利用手套箱保護曝氣環境濕度下，不需加熱烘烤即可達到極低之釋氣率。拋光擠型鋁合金之第1、第10以及第24小時之熱釋氣率值分別為 q1=1.6x10-11mbar.L/s.cm2、q10=6.0x10-13 mbar.L/s.cm2、q24=1.6x10-13 mbar.L/s.cm2分別比酒精加工鋁合金低了1.5倍、5.5倍與10倍。顯示環境溼度對釋氣率有絕對的影響，且表面粗糙度較低之拋光擠型鋁合金在相同實驗條件下，可以達到較低之釋氣率。在釋氣率曲線斜率上，酒精加工鋁合金之釋氣率曲線斜率可達-2.1，而拋光擠型鋁合金則只到達-1.8之斜率。從本論文熱釋氣以及殘留氣體質譜之結果分析斜率為-2的機制與表面多孔性以及表面氣體裂解組合之作用有關。

關鍵字

熱釋氣 ； 釋氣率 ； 真空 ； 鋁合金 ； 拋光擠型鋁合金真空腔

並列摘要

Thermal outgassing rate measurements and residual gas analyses were
used to study two aluminum-alloy chambers, which had different surface treatments. One chamber was machined with alcohol, and the other was extruded by using a diamond-tip die to provide smooth internal surface . The effect of surface roughness on the outgassing rate and the mechanism of the slope -2 in outgassing rate curve were investigated in this work. The chambers were vented to dry nitrogen atmospheres with different venting conditions in order to obtain lower outgassing rates.
The results showed that in the experiments of venting to extremely with a humidity of dry nitrogen gas(1.3ppb), to protect the vacuum chamber from atmosphere environment by glove box, had the lowest outgassing rate among the others. The outgassing rates of the extruded aluminum chamber at the 1st,10th and 24th hour were shown as
q1=1.6x10-11 mbar.L/s.cm2, q10=6.0x10-13 mbar.L/s.cm2 and q24=1.6x10-13 mbar.L/s.cm2,which were 1.5,5.5 and 10 times relatively lower than the chamber cleaned with alcohol.
It was shown that the environmental humidity had a great effect on the outgassing rate. From the results of the outgassing rate curve, the slope of the alcohol treated aluminum chamber was -2 .1 at the first hour after pumping and the slope of the ex-treated aluminum chamber was -1.8. In summary, the results from this research implied that the mechanism of the slope -2 of the outgassing rate curve has relations with the surface porosity and the gas dissociation.

並列關鍵字

thermal outgas ； outgassing rate ； vacuum ； Aluminum alloy ； extruded aluminum chamber

參考文獻

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