熱(re)浸鍍(du)(du)(du)(du)鋅(xin)(xin)是(shi)一種在電(dian)力、交(jiao)通和建筑等生產(chan)實際(ji)(ji)中(zhong)得(de)到廣泛應用，用來防止(zhi)鋼鐵產(chan)品腐蝕(shi)的(de)最常用技(ji)術。鋅(xin)(xin)液中(zhong)Al的(de)加入(ru)(ru)，使(shi)鍍(du)(du)(du)(du)層(ceng)不(bu)僅具有(you)(you)鋁鍍(du)(du)(du)(du)層(ceng)的(de)耐(nai)蝕(shi)性(xing)(xing)和高(gao)溫(wen)抗氧化(hua)性(xing)(xing)，還具有(you)(you)鋅(xin)(xin)鍍(du)(du)(du)(du)層(ceng)的(de)陰極保護性(xing)(xing)。因(yin)此，Zn-Al合金(jin)(jin)鍍(du)(du)(du)(du)層(ceng)以(yi)其(qi)高(gao)耐(nai)蝕(shi)性(xing)(xing)、良好的(de)力學性(xing)(xing)能(neng)和涂(tu)裝性(xing)(xing)能(neng)，正在漸漸取代純鋅(xin)(xin)鍍(du)(du)(du)(du)層(ceng)。1984年(nian)國際(ji)(ji)鉛(qian)鋅(xin)(xin)研究組織(zhi)(ILZRO)開發了(le)一種含(han)有(you)(you)5%Al和微量稀(xi)土(tu)的(de)合金(jin)(jin)鍍(du)(du)(du)(du)層(ceng)，商(shang)品名為“Galfan”，它(ta)的(de)耐(nai)蝕(shi)性(xing)(xing)是(shi)純鋅(xin)(xin)鍍(du)(du)(du)(du)層(ceng)的(de)2～3倍。為了(le)適(shi)應不(bu)斷提高(gao)的(de)耐(nai)腐蝕(shi)要求，其(qi)他合金(jin)(jin)元素被加入(ru)(ru)到Zn-Al合金(jin)(jin)鍍(du)(du)(du)(du)層(ceng)中(zhong)。Mg加入(ru)(ru)Zn-Al合金(jin)(jin)鍍(du)(du)(du)(du)層(ceng)中(zhong)后(hou)有(you)(you)細化(hua)晶粒和強化(hua)晶界的(de)作(zuo)用。日本日新制鋼公司在20世紀(ji)90年(nian)代開發成功商(shang)品名為ZAM的(de)鋅(xin)(xin)鋁鎂鍍(du)(du)(du)(du)層(ceng)合金(jin)(jin)，其(qi)成分為Zn-6％A1-3％Mg，其(qi)耐(nai)蝕(shi)性(xing)(xing)為純鋅(xin)(xin)鍍(du)(du)(du)(du)層(ceng)的(de)10倍，為Galfan合金(jin)(jin)的(de)5倍。目前，已有(you)(you)許多(duo)研究人員對Zn-Al-Mg合金(jin)(jin)鍍(du)(du)(du)(du)層(ceng)開展了(le)科研工(gong)作(zuo)，但是(shi)關于鍍(du)(du)(du)(du)層(ceng)形(xing)(xing)貌(mao)結(jie)構及(ji)(ji)其(qi)對性(xing)(xing)能(neng)影(ying)響(xiang)的(de)相(xiang)關文(wen)獻十分有(you)(you)限。本文(wen)在Zn-6%Al鋅(xin)(xin)池中(zhong)加入(ru)(ru)不(bu)同含(han)量Mg，通過SEM、EDS以(yi)及(ji)(ji)XRD對鍍(du)(du)(du)(du)層(ceng)進行分析，結(jie)合相(xiang)圖研究Mg對Zn-6%Al合金(jin)(jin)鍍(du)(du)(du)(du)層(ceng)凝固組織(zhi)及(ji)(ji)形(xing)(xing)貌(mao)的(de)變(bian)化(hua)，進一步(bu)分析這種變(bian)化(hua)對鍍(du)(du)(du)(du)層(ceng)耐(nai)蝕(shi)性(xing)(xing)的(de)影(ying)響(xiang)。

　　在實驗室用井(jing)式爐以及(ji)石(shi)墨粘土坩(gan)堝(guo)熔煉合金鋅浴，Zn錠、Al錠和Mg錠的純度均為(wei)(wei)99.9%，熱浸(jin)鍍(du)基體為(wei)(wei)99.96%高(gao)純Fe片(pian)，使(shi)用線切割機切成15mm×15mm×1mm的試片(pian)，鋅池設計溫(wen)度460℃。鐵片(pian)用預(yu)磨(mo)(mo)機打磨(mo)(mo)→15%的NaOH溶液(ye)堿洗2～3min除油(you)(70℃)→清水(shui)沖洗→15%的HCl溶液(ye)酸洗3min除銹→清水(shui)沖洗→助(zhu)鍍(du)3min(70～90℃)→干(gan)燥→熱浸(jin)鍍(du)10s→冷卻。助(zhu)鍍(du)劑為(wei)(wei)每100ml水(shui)中10.7g的ZnCl2，10g的NH4Cl，8g的SnCl2配(pei)置(zhi)的水(shui)溶液(ye)。

　　Mg加(jia)入(ru)量(liang)(liang)在(zai)(zai)3%以(yi)內，Zn-6%Al合(he)(he)金(jin)鍍(du)層(ceng)(ceng)(ceng)(ceng)凝固(gu)過程(cheng)為：先(xian)(xian)出現(xian)初生(sheng)(sheng)富Al的(de)(de)fcc相(xiang)(xiang)(xiang)，隨(sui)后富Zn的(de)(de)hcp相(xiang)(xiang)(xiang)作為第二相(xiang)(xiang)(xiang)在(zai)(zai)鍍(du)層(ceng)(ceng)(ceng)(ceng)中(zhong)形核生(sheng)(sheng)長，當(dang)液相(xiang)(xiang)(xiang)成(cheng)分到達共(gong)晶(jing)點成(cheng)分后發生(sheng)(sheng)共(gong)晶(jing)轉(zhuan)變，生(sheng)(sheng)成(cheng)了Zn/Al/MgZn2三元(yuan)共(gong)晶(jing)。Mg含量(liang)(liang)為3%～4%，凝固(gu)生(sheng)(sheng)成(cheng)的(de)(de)第二相(xiang)(xiang)(xiang)為MgZn2，而(er)不再是Zn-hcp；Mg含量(liang)(liang)超(chao)過4%，凝固(gu)過程(cheng)中(zhong)MgZn2作為初生(sheng)(sheng)相(xiang)(xiang)(xiang)率(lv)先(xian)(xian)在(zai)(zai)鍍(du)層(ceng)(ceng)(ceng)(ceng)中(zhong)形核，第二項為Al-fcc，最后發生(sheng)(sheng)共(gong)晶(jing)反(fan)應生(sheng)(sheng)成(cheng)Zn/Al/MgZn2三元(yuan)共(gong)晶(jing)。電化(hua)學腐(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)結果顯示，Zn-6%Al鍍(du)層(ceng)(ceng)(ceng)(ceng)的(de)(de)耐(nai)腐(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)性(xing)(xing)能隨(sui)Mg含量(liang)(liang)增加(jia)而(er)提(ti)高(gao)，Mg加(jia)入(ru)合(he)(he)金(jin)鍍(du)層(ceng)(ceng)(ceng)(ceng)中(zhong)能增加(jia)Zn-Al合(he)(he)金(jin)鍍(du)層(ceng)(ceng)(ceng)(ceng)的(de)(de)耐(nai)腐(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)性(xing)(xing)能，Zn-6%Al-3%Mg的(de)(de)合(he)(he)金(jin)鍍(du)層(ceng)(ceng)(ceng)(ceng)腐(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)速率(lv)最低，耐(nai)蝕(shi)(shi)(shi)(shi)(shi)性(xing)(xing)最好，但加(jia)入(ru)的(de)(de)Mg含量(liang)(liang)繼續升(sheng)高(gao)后耐(nai)蝕(shi)(shi)(shi)(shi)(shi)性(xing)(xing)有明顯下降。比較Zn-6%Al和(he)Zn-6%Al-3%Mg合(he)(he)金(jin)鍍(du)層(ceng)(ceng)(ceng)(ceng)可發現(xian)，Zn-6%Al的(de)(de)腐(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)產物為Zn5(OH)8Cl2.H2O、Zn(OH)2和(he)少量(liang)(liang)ZnO，而(er)Zn-6%Al-3%Mg合(he)(he)金(jin)鍍(du)層(ceng)(ceng)(ceng)(ceng)在(zai)(zai)鹽(yan)霧腐(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)后表面主要形成(cheng)了難(nan)溶(rong)、致密(mi)、低導電性(xing)(xing)的(de)(de)腐(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)產物Zn5(OH)8Cl2.H2O。說明Mg的(de)(de)加(jia)入(ru)抑制了Zn(OH)2向(xiang)ZnO而(er)促進了向(xiang)Zn5(OH)8Cl2.H2O轉(zhuan)變，大大提(ti)高(gao)了鍍(du)層(ceng)(ceng)(ceng)(ceng)的(de)(de)耐(nai)腐(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)性(xing)(xing)。