添加鐵、鉛、銅元素對鋁基複合材料性質之影響

Effect of Fe, Pb and Cu additives on the properties of Al matrix composites

莊士鋒(Shih-Feng Chuang)

指導教授 ： 李勝隆

國立中央大學/工學院/機械工程學系/博士(2007年)

摘要

本研究以擠壓鑄造法製作純Al、A356、A356+0.8Fe三種Al基Nd-Fe-B複合磁石，以探討Fe元素對複合磁石之微結構、機械性質及磁性質的影響，並以熱壓燒結法製作Al-Si-Cu-Pb複合材料，以探討添加Pb、Cu元素對其微結構、硬度、磨耗、腐蝕及磨耗腐蝕等性質的影響。
由實驗結果得知，三種Al基Nd-Fe-B複合磁石在相同的體積分率(72±1%)下，純Al基地之Nd-Fe-B複合磁石之反應層最為明顯，隨著Al基地中Fe含量的增加，反應層厚度相對減少，而在A356+0.8%Fe合金基地之Nd-Fe-B複合磁石中，其反應層最少。三種高體積分率之複合磁石在抗彎曲強度、硬度等機械性質上，不因Al基地的不同而有顯著的差異。在磁性質方面，隨著Al基地中Fe含量的增加，Nd-Fe-B複合磁石的殘留磁束密度Br值由0.51 T增加到0.66 T，而磁能積(BH)max由36.8 kJ/m3增加到63.2 kJ/m3，且不影響複合磁石之本質矯頑磁力iHc，幾乎與原Nd-Fe-B磁粉相同。
以熱壓燒結法製作Al-20Si基複合材料，添加5或10 wt%的Pb以及3 wt%的Cu元素，在無潤滑情形下進行磨耗試驗，並在3.5 wt%氯化鈉(NaCl)水溶液中(pH=6.7)進行磨耗腐蝕試驗。
結果顯示，隨Pb的添加量增加，Al-Si-Pb及Al-Si-Cu-Pb複合材料的乾磨耗量降低，添加Cu可提高Al-Si複合材料的硬度，並降低乾磨耗量。複合材料的腐蝕電位Ecorr，無論在熱壓燒結或熱處理後，皆因Cu的添加而上升，並隨Pb的添加量增加而下降。腐蝕電流密度icorr在熱壓燒結後，因Pb與Cu的添加而增加，在熱處理後Al-Si-Cu及Al-Si-Cu-Pb複合材料的腐蝕電流密度icorr降低。添加Pb元素可提高Al-Si及Al-Si-Cu複合材料的磨耗腐蝕性質，在本研究中，同時添加Pb與Cu的Al-Si-Cu-Pb複合材料具有最佳的乾磨耗及磨耗腐蝕性質。

關鍵字

複合磁石 ； 鋁矽複合材料 ； 鐵 ； 銅 ； 鉛 ； 擠壓鑄造 ； 熱壓燒結 ； 磁性質 ； 磨耗 ； 腐蝕 ； 釹鐵硼 ； 金屬基複合材料

並列摘要

This work studies the effect of Fe on the microstructure, mechanical and magnetic properties of three aluminum metal matrix Nd-Fe-B composite magnets. The composite magnets are prepared by squeezing three aluminum alloys (pure Al, A356 alloy and A356+0.8%Fe alloy) into preformed Nd-Fe-B magnetic powder.
The results indicate that the pure Al-matrix Nd-Fe-B composite magnet has the most active reaction layer. However, the thickness of the reaction layer decreases as the Fe content in the matrix increases. Increasing the Fe content in aluminum matrix increases the remanence (Br) of the composite magnets from 0.51 to 0.66 T, and increases the energy product ((BH)max) from 36.8 to 63.2 kJ/m3. The intrinsic coercivity (iHc) of these composite magnets is nearly the same as the original magnetic powder.
Dispersed lead and copper particles in aluminum-silicon matrix composites were fabricated by hot pressing. Effects of the addition of 5 wt.% and 10 wt.% lead and 3 wt.% copper particles on wear and wear-corrosion properties of Al-20Si composites have been evaluated. Wear is performed at ambient without lubricant, and wear-corrosion is executed in 3.5 wt.% NaCl solution (pH 6.7).
The results show that the dry wear loss of Al-Si-Pb and Al-Si-Cu-Pb composites decreased as the Pb content increased. The hardness increased and the dry wear loss was reduced with the addition of Cu particles. The corrosion potential, Ecorr, increased with the presence of Cu and with the decrease of the Pb content, both for pressed and heat-treated conditions. The corrosion current density, icorr, increased with Cu and Pb incorporation into composites in the as pressed state, and decreased after heat treatment for Al-Si-Cu and Al-Si-Cu-Pb composites. The wear-corrosion property was improved by the addition of the Pb phase to Al-Si and Al-Si-Cu composites. Al-Si-Cu-Pb composites exhibited better dry wear and wear corrosion resistance than other composites in this study.

並列關鍵字

Squeeze ； Nd-Fe-B ； MMC ； Composite magnets ； Hot pressing ； Magnetic properties ； Wear ； Corrosion ； Cu ； Pb ； Fe ； Al-Si composite

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