1. 不銹鋼工件在電化學拋光前必須徹底除油,并用去污粉擦洗,以免油污污染拋光槽液。


 2. 在使(shi)(shi)用(yong)過(guo)程中需(xu)要經常(chang)測量(liang)(liang)電化(hua)(hua)學拋(pao)(pao)光液的相(xiang)(xiang)對密度。如果相(xiang)(xiang)對密度小于配方規(gui)定(ding)值,表(biao)(biao)明電化(hua)(hua)學拋(pao)(pao)光液含(han)水(shui)(shui)過(guo)多(duo),可用(yong)蒸發法將(jiang)溶(rong)液加熱至80℃以上,將(jiang)多(duo)余水(shui)(shui)分除去,體積不足部分可按配方比例補(bu)充磷酸和硫酸。在工件進入電化(hua)(hua)學拋(pao)(pao)光槽前,最好將(jiang)工件上所附著的水(shui)(shui)分瀝干(gan)或吹干(gan)。如果相(xiang)(xiang)對密度太高,超(chao)過(guo)配方規(gui)定(ding)值,表(biao)(biao)示水(shui)(shui)分過(guo)少(shao),要適當(dang)補(bu)充少(shao)量(liang)(liang)水(shui)(shui),使(shi)(shi)相(xiang)(xiang)對密度降至規(gui)定(ding)值。有(you)條件的最好按周期化(hua)(hua)驗分析溶(rong)液,根據(ju)結果及時進行調整。


3. 溶液的(de)老化


  由于拋光過程中不銹鋼表面的溶解,溶液中的鐵、鎳、鉻含量將逐漸升高,此時溶液逐漸失去拋光能力。無論如何增高溫度,開大電流,均無助于恢復拋光能力。分析溶液,如鐵含量超過60g/L,三價鉻含量超過25g/L,說明溶液已經老化,在高濃度磷酸的存在下,鐵、鉻(三價)均呈酸式磷酸二氫鐵[Fe(H2PO4)3]或磷酸二氫鉻[Cr(H2PO4)3]形式存在,不易沉淀,只有當形成磷酸鐵(FePO4)或磷酸鉻(CrPO4)時才會沉淀于槽底。磷酸濃度較低的溶液具有自凈化能力。對于拋光溶液再生,恢復拋光能力,有兩種方法可供選擇。一個方法是適當用水稀釋溶液,降低酸度,鐵、鉻、鎳等雜質可局部呈磷酸鹽沉淀,除去槽底沉淀,然后再加熱蒸發除去水分,恢復原有的相對密度,此法操作起來較繁瑣,需要消耗較大的能源和時間。另一方法是更換部分溶液,最好保留20%的舊溶液,補充80%的新溶液。可以少通電或不通電處理,很快即可實現正常拋光。


4. 清理(li)陰極鉛板


 在拋光過程中陰極(ji)鉛板表面(mian)會沉(chen)(chen)積出(chu)一層厚厚的鐵、鎳等雜質,影響陰極(ji)表面(mian)導(dao)電(dian),導(dao)致電(dian)流下(xia)降,使拋光表面(mian)的陽極(ji)電(dian)流密度也上不去,嚴重(zhong)影響拋光質量(liang)。因此,要(yao)及時將陰極(ji)板上的沉(chen)(chen)積物除去,有時形成硬質厚膜,要(yao)強(qiang)力敲打才能除下(xia),最后沖(chong)洗干凈,以保持整個電(dian)路通暢(chang)。


5. 陰(yin)極與陽極面積比


 陰極面積控制在(zai)陽極面積的(de)1/2~1/3.5.在(zai)此情況下,可(ke)以防止(zhi)三價(jia)(jia)鉻(ge)的(de)增長,過(guo)多的(de)三價(jia)(jia)鉻(ge)在(zai)陽極表(biao)面被氧化成六價(jia)(jia)鉻(ge)。三價(jia)(jia)鉻(ge)含量(liang)過(guo)多,易使拋光液老化。


6. 陰陽極之(zhi)間的極距


 陰極與陽(yang)極之(zhi)間的(de)距(ju)離(li)過大(da)、電阻增(zeng)(zeng)大(da),電能消耗增(zeng)(zeng)大(da),溶液(ye)容易升溫(wen),影響拋(pao)光質量。距(ju)離(li)過小(xiao),易造(zao)成(cheng)短路打火(huo),燒黑制品。陰極與陽(yang)極之(zhi)間的(de)距(ju)離(li)以100~300mm為宜。


7. 象形陰極


 對(dui)拋光(guang)一(yi)些復雜的(de)大型工件,可制作象形陰極,以(yi)保持陽(yang)極電流分布均勻,特(te)別是對(dui)內腔工件,有適(shi)當的(de)象形陰極安置(zhi)在內腔中,才能使內腔各(ge)部位拋光(guang)一(yi)致。


8. 進(jin)出(chu)槽(cao)要(yao)切(qie)斷電源


 在電(dian)(dian)化學拋光時,由于電(dian)(dian)流(liu)密度較高,給(gei)電(dian)(dian)流(liu)較大,因此,工件在進出拋光槽(cao)時,要先切(qie)斷電(dian)(dian)源,不可帶電(dian)(dian)掛或摘(zhai)夾具(ju),以(yi)防止產(chan)生電(dian)(dian)火花,引起電(dian)(dian)解產(chan)生,并會使聚集在槽(cao)面上(shang)的(de)氫(qing)氣和氧(yang)氣混(hun)合氣發生爆炸。


9. 控制槽(cao)液(ye)溫度(du)


 由于強大的電流通過槽液,會使槽液升溫,在連續操作中要采取冷卻措施,使用冷凍機冷卻不斷升溫的槽液。拋光液的溫應適度維持在規定的工藝范圍內,使不銹鋼表面拋光整平速率維持正常,以便有效降低電解液的黏度,減少陽極黏膜的厚度,加速陽極溶解產物的擴散,使溶液對流加快,有利于陽極上滯留氣泡脫附,避免產生斑點、麻點。溫度過高,會導致溶液過熱,加速六價鉻向三價鉻的轉變(Cr6++3e→Cr3+),易產生表面腐蝕。溫度過低,使溶液黏度增大,陽極表面黏膜增厚,不利于陽極溶解物的擴散,使拋光整平效果明顯降低。


10. 控制合適的陽極電流密度


  不(bu)(bu)銹(xiu)鋼零件電(dian)(dian)(dian)(dian)(dian)(dian)(dian)化學拋(pao)光(guang)時,陽(yang)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)密(mi)(mi)(mi)(mi)度(du)與金屬(shu)的(de)(de)溶解(jie)幾(ji)乎(hu)呈正比(bi)。只有(you)選擇好陽(yang)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)密(mi)(mi)(mi)(mi)度(du),并控制在一定(ding)的(de)(de)陽(yang)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)區間,才能獲得(de)良(liang)好的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)化學拋(pao)光(guang)質量(liang),陽(yang)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)密(mi)(mi)(mi)(mi)度(du)的(de)(de)最佳(jia)值,要根(gen)據(ju)不(bu)(bu)同的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)解(jie)液(ye)配方(fang),通過(guo)實際拋(pao)光(guang),觀(guan)(guan)察(cha)拋(pao)光(guang)所得(de)最佳(jia)值確定(ding)。在合(he)適的(de)(de)陽(yang)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)密(mi)(mi)(mi)(mi)度(du)下(xia),根(gen)據(ju)黏膜理論(lun),微觀(guan)(guan)表面凸出部位(wei)優先溶解(jie),有(you)利于整平精飾(shi)表面。陽(yang)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)密(mi)(mi)(mi)(mi)度(du)過(guo)小,零件表面發生(sheng)一般(ban)的(de)(de)陽(yang)極(ji)溶解(jie),起不(bu)(bu)到拋(pao)光(guang)效(xiao)果。陽(yang)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)密(mi)(mi)(mi)(mi)度(du)過(guo)大,黏膜被擊(ji)穿,氧氣猛烈(lie)析出呈氣流(liu)(liu)(liu)狀,表面過(guo)熱,導致電(dian)(dian)(dian)(dian)(dian)(dian)(dian)拋(pao)光(guang)液(ye)擴散加劇,黏膜被破壞,不(bu)(bu)復(fu)存在,發生(sheng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)化學腐蝕。所以在電(dian)(dian)(dian)(dian)(dian)(dian)(dian)拋(pao)光(guang)過(guo)程中必(bi)須控制陽(yang)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)密(mi)(mi)(mi)(mi)度(du)在最佳(jia)值,也就是(shi)在確定(ding)的(de)(de)工藝(yi)范(fan)圍(wei)內。


11. 陽極移動(dong)


 陽極移(yi)動使陽極溶解產物加快擴(kuo)散出(chu)去,起到攪拌作用,有效地排(pai)除陽極表面滯(zhi)留的氣泡,避免產生的氣流(liu)生成條紋(wen),防止局(ju)部(bu)過(guo)熱造成表面過(guo)腐(fu)蝕(shi)。陽極移(yi)動有助于提高陽極電流(liu)密度,提高不銹鋼(gang)零(ling)件的電化學(xue)拋(pao)光表面質量(liang)。


12. 氯離子的危害


 在(zai)(zai)電化學拋光液中不允許有活性(xing)氯(lv)離(li)子(zi)存在(zai)(zai),氯(lv)離(li)子(zi)能破(po)壞電化學拋光中表面(mian)形成的(de)保(bao)護性(xing)黏(nian)膜,使不銹鋼表面(mian)形成過腐蝕性(xing)的(de)麻點。氯(lv)離(li)子(zi)可(ke)在(zai)(zai)陽極(ji)高電流密度上氧化成氯(lv)氣(qi)逸(yi)出而除(chu)去。氯(lv)離(li)子(zi)的(de)來源可(ke)能是用鹽酸酸洗后未(wei)洗凈而帶入槽液,或原料(liao)中的(de)不純物氯(lv)離(li)子(zi)引入。


13. 六價鉻(ge)和三(san)價鉻(ge)的最(zui)佳配比(bi)


 在(zai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)學(xue)拋(pao)光(guang)液(ye)(ye)(ye)(ye)(ye)中(zhong)(zhong)六(liu)(liu)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)有氧化(hua)(hua)性,對不銹鋼表(biao)面起(qi)鈍化(hua)(hua)保護作(zuo)(zuo)用,三(san)(san)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)對維護電(dian)(dian)(dian)(dian)(dian)(dian)(dian)拋(pao)光(guang)有作(zuo)(zuo)用。新配(pei)(pei)成(cheng)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)拋(pao)光(guang)液(ye)(ye)(ye)(ye)(ye)如(ru)果(guo)沒有化(hua)(hua)學(xue)反應(ying)產生三(san)(san)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge),還不能(neng)獲(huo)得良好的(de)(de)拋(pao)光(guang)表(biao)面。只有當電(dian)(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)到溶(rong)(rong)液(ye)(ye)(ye)(ye)(ye)中(zhong)(zhong)有一(yi)定量的(de)(de)三(san)(san)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)存(cun)在(zai)時,才能(neng)出(chu)現理想的(de)(de)拋(pao)光(guang)表(biao)面。如(ru)果(guo)配(pei)(pei)方中(zhong)(zhong)加(jia)(jia)有鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)酐(gan)(gan),即六(liu)(liu)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge),通過(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)反應(ying),在(zai)陰(yin)極(ji)上產生氫氣還原部分(fen)(fen)(fen)六(liu)(liu)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)成(cheng)為(wei)(wei)(wei)三(san)(san)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge);如(ru)果(guo)配(pei)(pei)方中(zhong)(zhong)沒有鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)酐(gan)(gan),則三(san)(san)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)要靠(kao)陽(yang)極(ji)溶(rong)(rong)解(jie)(jie)不銹鋼所含(han)(han)的(de)(de)鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)而得。這就是(shi)(shi)為(wei)(wei)(wei)什(shen)么新配(pei)(pei)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)拋(pao)光(guang)液(ye)(ye)(ye)(ye)(ye)要充分(fen)(fen)(fen)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)后(hou)才能(neng)進(jin)行正常(chang)的(de)(de)拋(pao)光(guang)工作(zuo)(zuo)。在(zai)含(han)(han)有鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)酐(gan)(gan)的(de)(de)溶(rong)(rong)液(ye)(ye)(ye)(ye)(ye)中(zhong)(zhong),加(jia)(jia)入明(ming)膠或(huo)甘油(you),它(ta)們能(neng)和(he)鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)酐(gan)(gan)起(qi)強(qiang)烈的(de)(de)還原反應(ying),部分(fen)(fen)(fen)六(liu)(liu)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)轉變(bian)為(wei)(wei)(wei)三(san)(san)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(Cr3+)。六(liu)(liu)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)是(shi)(shi)黃(huang)(huang)色(se)(se)的(de)(de),三(san)(san)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)是(shi)(shi)綠(lv)色(se)(se)的(de)(de)。它(ta)們在(zai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)液(ye)(ye)(ye)(ye)(ye)中(zhong)(zhong)使溶(rong)(rong)液(ye)(ye)(ye)(ye)(ye)呈(cheng)黃(huang)(huang)綠(lv)色(se)(se)。這就是(shi)(shi)為(wei)(wei)(wei)什(shen)么通電(dian)(dian)(dian)(dian)(dian)(dian)(dian)處理后(hou)才可電(dian)(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)拋(pao)光(guang)。最佳的(de)(de)拋(pao)光(guang)質(zhi)量是(shi)(shi)在(zai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)過(guo)程(cheng)的(de)(de)中(zhong)(zhong)間階段。在(zai)生產過(guo)程(cheng)中(zhong)(zhong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)拋(pao)光(guang)液(ye)(ye)(ye)(ye)(ye)要保持(chi)(chi)黃(huang)(huang)綠(lv)色(se)(se)。此時,根(gen)據化(hua)(hua)學(xue)分(fen)(fen)(fen)析數據,六(liu)(liu)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)與(yu)三(san)(san)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)的(de)(de)配(pei)(pei)比(bi)是(shi)(shi):含(han)(han)Cr6+30%,含(han)(han)Cr3+70%.為(wei)(wei)(wei)了(le)維持(chi)(chi)該配(pei)(pei)比(bi),可觀(guan)察(cha)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)液(ye)(ye)(ye)(ye)(ye)的(de)(de)顏色(se)(se),如(ru)果(guo)顏色(se)(se)呈(cheng)黃(huang)(huang)色(se)(se)為(wei)(wei)(wei)主,表(biao)明(ming)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)液(ye)(ye)(ye)(ye)(ye)含(han)(han)Cr6+偏高,可加(jia)(jia)入適量的(de)(de)明(ming)膠或(huo)甘油(you),使其部分(fen)(fen)(fen)六(liu)(liu)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)還原為(wei)(wei)(wei)三(san)(san)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge),或(huo)通過(guo)大(da)(da)陰(yin)極(ji)小陽(yang)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)產生三(san)(san)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)。如(ru)果(guo)顏色(se)(se)呈(cheng)深綠(lv)色(se)(se),表(biao)明(ming)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)液(ye)(ye)(ye)(ye)(ye)含(han)(han)Cr3+高了(le),按比(bi)例適量加(jia)(jia)入用水溶(rong)(rong)解(jie)(jie)好的(de)(de)鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)酐(gan)(gan)溶(rong)(rong)液(ye)(ye)(ye)(ye)(ye),或(huo)通過(guo)大(da)(da)陽(yang)極(ji)小陰(yin)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)拋(pao)光(guang)液(ye)(ye)(ye)(ye)(ye),使三(san)(san)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)部分(fen)(fen)(fen)轉變(bian)成(cheng)六(liu)(liu)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)(ge)。同時可改善(shan)溶(rong)(rong)液(ye)(ye)(ye)(ye)(ye)的(de)(de)拋(pao)光(guang)質(zhi)量。


14. 金(jin)屬拋除量(liang)


 如(ru)果電(dian)解拋(pao)光時陽(yang)極(ji)電(dian)流密度為(wei)(wei)20A/d㎡,時間為(wei)(wei)4min時,用工具金相顯微鏡觀測,不(bu)銹鋼(gang)零(ling)件的(de)螺紋內徑的(de)金屬拋(pao)除量為(wei)(wei)每分(fen)鐘約0.001mm,螺紋外徑的(de)金屬拋(pao)除量為(wei)(wei)0.002mm,齒形(xing)基本(ben)無變化(hua),僅齒的(de)頂部略(lve)有拋(pao)鈍。陽(yang)極(ji)電(dian)流密度增加,其金屬拋(pao)除量呈比例增大。對于精密尺寸(cun)的(de)不(bu)銹鋼(gang)零(ling)件的(de)尺寸(cun)應考慮電(dian)化(hua)學拋(pao)光后的(de)金屬拋(pao)除量(損耗(hao))。


15. 電(dian)焊或熱處理后零件的電(dian)化學(xue)拋光(guang)


 凡電焊(han)或(huo)熱處理后(hou)的零件在電化學拋光(guang)時按兩次進行,第一次進槽拋光(guang)3~5min后(hou)取出,將已(yi)疏松(song)了的焊(han)渣和熱處理氧化皮用金(jin)屬絲刷將它刷掉(diao),或(huo)用小錘(chui)敲掉(diao),再第二次進槽再拋光(guang)3~5min,可(ke)獲(huo)得較好的效果。


16. 中和工序


 經過電化(hua)學(xue)拋光后(hou)的(de)零件(jian)(jian),如果不再(zai)進(jin)行后(hou)續(xu)加工,如電鍍、著色等其他工序,要(yao)進(jin)行鈍化(hua)和(he)中和(he)。中和(he)的(de)作用是(shi)充分地(di)消(xiao)除在電化(hua)學(xue)拋光和(he)鈍化(hua)后(hou)表面所吸附的(de)酸(suan)性物質。中和(he)一般是(shi)在碳酸(suan)鈉20~30g/L的(de)溶液中進(jin)行的(de)。路云鶴(he)認為,經過電化(hua)學(xue)拋光后(hou)的(de)零件(jian)(jian)表面有(you)一層均(jun)勻的(de)鈍化(hua)膜,可(ke)(ke)不需(xu)要(yao)再(zai)進(jin)行鈍化(hua)處理。不銹鋼零件(jian)(jian)電化(hua)學(xue)拋光后(hou),經過40℃的(de)溫水(shui)清洗,再(zai)冷水(shui)清洗,中和(he)并清洗后(hou)用壓縮(suo)空氣(qi)吹(chui)干,才可(ke)(ke)以有(you)效(xiao)地(di)避免殘留酸(suan)液腐蝕拋光表面。