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)用(yong)過程中需要經常(chang)測量電化(hua)學(xue)拋光(guang)液的相(xiang)對密度。如果(guo)(guo)相(xiang)對密度小于配方(fang)(fang)規(gui)(gui)定值,表(biao)明電化(hua)學(xue)拋光(guang)液含水(shui)(shui)過多,可(ke)用(yong)蒸發法將(jiang)溶液加熱至(zhi)80℃以上,將(jiang)多余水(shui)(shui)分(fen)除去,體積不(bu)足部分(fen)可(ke)按配方(fang)(fang)比例補充磷酸和(he)硫酸。在工(gong)件進入電化(hua)學(xue)拋光(guang)槽前,最好將(jiang)工(gong)件上所附著(zhu)的水(shui)(shui)分(fen)瀝干(gan)(gan)或吹(chui)干(gan)(gan)。如果(guo)(guo)相(xiang)對密度太高,超過配方(fang)(fang)規(gui)(gui)定值,表(biao)示水(shui)(shui)分(fen)過少,要適(shi)當(dang)補充少量水(shui)(shui),使(shi)相(xiang)對密度降至(zhi)規(gui)(gui)定值。有條件的最好按周期化(hua)驗(yan)分(fen)析溶液,根據結果(guo)(guo)及時進行調整。


3. 溶(rong)液的老化(hua)


  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(qing)理(li)陰極(ji)鉛板


 在拋(pao)光過(guo)程中(zhong)陰(yin)極(ji)(ji)鉛板表面會沉積出一層厚厚的鐵、鎳等雜質,影(ying)響陰(yin)極(ji)(ji)表面導(dao)電(dian)(dian),導(dao)致電(dian)(dian)流下降,使拋(pao)光表面的陽極(ji)(ji)電(dian)(dian)流密(mi)度也(ye)上(shang)不去,嚴重影(ying)響拋(pao)光質量。因此,要及時將(jiang)陰(yin)極(ji)(ji)板上(shang)的沉積物(wu)除(chu)去,有時形成(cheng)硬質厚膜,要強(qiang)力敲打才能除(chu)下,最后沖洗干凈,以(yi)保持(chi)整(zheng)個(ge)電(dian)(dian)路通暢。


5. 陰極與陽極面積比(bi)


 陰(yin)極(ji)面積控制在陽極(ji)面積的1/2~1/3.5.在此(ci)情況下,可(ke)以防止(zhi)三價鉻(ge)的增長,過(guo)多的三價鉻(ge)在陽極(ji)表面被氧化成六價鉻(ge)。三價鉻(ge)含量過(guo)多,易使拋(pao)光液老化。


6. 陰陽極之間的極距(ju)


 陰(yin)極與陽極之間(jian)的距(ju)離(li)過(guo)大、電阻增大,電能消耗(hao)增大,溶液容易(yi)升溫,影響(xiang)拋光質量。距(ju)離(li)過(guo)小,易(yi)造成短路打火,燒黑制品。陰(yin)極與陽極之間(jian)的距(ju)離(li)以100~300mm為宜。


7. 象形陰極


 對(dui)拋(pao)光(guang)一(yi)些復雜的大型工件,可制作象(xiang)形(xing)陰極(ji),以保持陽極(ji)電(dian)流(liu)分布(bu)均勻(yun),特別是對(dui)內(nei)腔(qiang)工件,有適(shi)當的象(xiang)形(xing)陰極(ji)安置在內(nei)腔(qiang)中,才能使內(nei)腔(qiang)各部位拋(pao)光(guang)一(yi)致。


8. 進出槽要切(qie)斷(duan)電源(yuan)


 在(zai)電(dian)(dian)化學(xue)拋光時(shi),由于電(dian)(dian)流(liu)密度較(jiao)(jiao)高,給電(dian)(dian)流(liu)較(jiao)(jiao)大,因此,工件(jian)在(zai)進出拋光槽時(shi),要先切斷電(dian)(dian)源,不可帶電(dian)(dian)掛或摘夾具,以防止產生(sheng)電(dian)(dian)火(huo)花,引(yin)起電(dian)(dian)解產生(sheng),并會使(shi)聚集在(zai)槽面上的氫氣和氧氣混合氣發生(sheng)爆炸(zha)。


9. 控(kong)制槽液溫度


 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(de)陽極(ji)電流密度


  不(bu)銹鋼零(ling)件(jian)(jian)電(dian)化(hua)學(xue)拋(pao)(pao)光(guang)(guang)(guang)時,陽(yang)(yang)(yang)極(ji)電(dian)流密(mi)度(du)與金屬的(de)溶(rong)(rong)解(jie)幾乎呈正比。只有選擇好陽(yang)(yang)(yang)極(ji)電(dian)流密(mi)度(du),并控制(zhi)在(zai)(zai)(zai)一定(ding)(ding)(ding)的(de)陽(yang)(yang)(yang)極(ji)電(dian)位區間,才(cai)能(neng)獲得良好的(de)電(dian)化(hua)學(xue)拋(pao)(pao)光(guang)(guang)(guang)質量,陽(yang)(yang)(yang)極(ji)電(dian)流密(mi)度(du)的(de)最(zui)(zui)佳(jia)(jia)值,要(yao)根據不(bu)同的(de)電(dian)解(jie)液(ye)配(pei)方,通過(guo)(guo)(guo)實際拋(pao)(pao)光(guang)(guang)(guang),觀察拋(pao)(pao)光(guang)(guang)(guang)所得最(zui)(zui)佳(jia)(jia)值確(que)定(ding)(ding)(ding)。在(zai)(zai)(zai)合適的(de)陽(yang)(yang)(yang)極(ji)電(dian)流密(mi)度(du)下(xia),根據黏膜理論(lun),微觀表面(mian)凸出(chu)部位優先溶(rong)(rong)解(jie),有利于整平精(jing)飾表面(mian)。陽(yang)(yang)(yang)極(ji)電(dian)流密(mi)度(du)過(guo)(guo)(guo)小,零(ling)件(jian)(jian)表面(mian)發(fa)(fa)生一般的(de)陽(yang)(yang)(yang)極(ji)溶(rong)(rong)解(jie),起不(bu)到拋(pao)(pao)光(guang)(guang)(guang)效果。陽(yang)(yang)(yang)極(ji)電(dian)流密(mi)度(du)過(guo)(guo)(guo)大,黏膜被(bei)擊(ji)穿,氧氣(qi)猛烈析出(chu)呈氣(qi)流狀,表面(mian)過(guo)(guo)(guo)熱,導致電(dian)拋(pao)(pao)光(guang)(guang)(guang)液(ye)擴散加劇,黏膜被(bei)破(po)壞,不(bu)復存在(zai)(zai)(zai),發(fa)(fa)生電(dian)化(hua)學(xue)腐蝕。所以在(zai)(zai)(zai)電(dian)拋(pao)(pao)光(guang)(guang)(guang)過(guo)(guo)(guo)程(cheng)中必須控制(zhi)陽(yang)(yang)(yang)極(ji)電(dian)流密(mi)度(du)在(zai)(zai)(zai)最(zui)(zui)佳(jia)(jia)值,也就是在(zai)(zai)(zai)確(que)定(ding)(ding)(ding)的(de)工藝范圍內。


11. 陽極移(yi)動


 陽(yang)極(ji)移動使陽(yang)極(ji)溶解產物(wu)加(jia)快擴散出去(qu),起到(dao)攪拌作用,有效(xiao)地排除陽(yang)極(ji)表(biao)(biao)面滯留的(de)(de)氣泡,避免產生(sheng)的(de)(de)氣流生(sheng)成(cheng)條紋(wen),防(fang)止(zhi)局(ju)部過熱造成(cheng)表(biao)(biao)面過腐蝕。陽(yang)極(ji)移動有助于提(ti)高陽(yang)極(ji)電流密度(du),提(ti)高不銹(xiu)鋼零件的(de)(de)電化學拋光表(biao)(biao)面質量(liang)。


12. 氯(lv)離子的(de)危(wei)害(hai)


 在(zai)電(dian)化(hua)學(xue)拋光(guang)液中(zhong)不(bu)允許有活性氯(lv)(lv)(lv)離(li)子(zi)存在(zai),氯(lv)(lv)(lv)離(li)子(zi)能破壞電(dian)化(hua)學(xue)拋光(guang)中(zhong)表(biao)面形(xing)成的(de)保(bao)護性黏膜,使不(bu)銹鋼(gang)表(biao)面形(xing)成過(guo)腐(fu)蝕(shi)性的(de)麻(ma)點。氯(lv)(lv)(lv)離(li)子(zi)可在(zai)陽極(ji)高(gao)電(dian)流密度上氧化(hua)成氯(lv)(lv)(lv)氣逸出而除(chu)去。氯(lv)(lv)(lv)離(li)子(zi)的(de)來源可能是用鹽(yan)酸酸洗后未洗凈而帶入槽液,或原料中(zhong)的(de)不(bu)純物氯(lv)(lv)(lv)離(li)子(zi)引入。


13. 六(liu)價鉻和(he)三價鉻的最佳配比


 在(zai)電(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)學拋(pao)(pao)(pao)光(guang)(guang)液(ye)(ye)(ye)(ye)(ye)(ye)中(zhong)(zhong)(zhong)(zhong)六(liu)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)有氧化(hua)(hua)性,對(dui)不銹(xiu)鋼表(biao)面起鈍化(hua)(hua)保(bao)(bao)護作(zuo)(zuo)用,三(san)(san)(san)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)對(dui)維護電(dian)(dian)(dian)(dian)(dian)(dian)拋(pao)(pao)(pao)光(guang)(guang)有作(zuo)(zuo)用。新配(pei)成的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)拋(pao)(pao)(pao)光(guang)(guang)液(ye)(ye)(ye)(ye)(ye)(ye)如(ru)果(guo)(guo)沒有化(hua)(hua)學反(fan)(fan)應(ying)產(chan)生(sheng)三(san)(san)(san)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge),還不能(neng)獲得(de)良(liang)好的(de)(de)拋(pao)(pao)(pao)光(guang)(guang)表(biao)面。只有當(dang)電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)到溶(rong)液(ye)(ye)(ye)(ye)(ye)(ye)中(zhong)(zhong)(zhong)(zhong)有一定(ding)量(liang)的(de)(de)三(san)(san)(san)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)存(cun)在(zai)時,才(cai)能(neng)出現(xian)理(li)想的(de)(de)拋(pao)(pao)(pao)光(guang)(guang)表(biao)面。如(ru)果(guo)(guo)配(pei)方中(zhong)(zhong)(zhong)(zhong)加有鉻(ge)(ge)(ge)(ge)(ge)酐(gan),即六(liu)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge),通過電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)反(fan)(fan)應(ying),在(zai)陰極(ji)(ji)上產(chan)生(sheng)氫氣(qi)還原(yuan)部分(fen)六(liu)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)成為(wei)三(san)(san)(san)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge);如(ru)果(guo)(guo)配(pei)方中(zhong)(zhong)(zhong)(zhong)沒有鉻(ge)(ge)(ge)(ge)(ge)酐(gan),則三(san)(san)(san)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)要(yao)靠陽極(ji)(ji)溶(rong)解(jie)(jie)不銹(xiu)鋼所含(han)(han)(han)的(de)(de)鉻(ge)(ge)(ge)(ge)(ge)而得(de)。這就是(shi)(shi)為(wei)什(shen)么(me)(me)新配(pei)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)拋(pao)(pao)(pao)光(guang)(guang)液(ye)(ye)(ye)(ye)(ye)(ye)要(yao)充(chong)分(fen)電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)后才(cai)能(neng)進行正常(chang)的(de)(de)拋(pao)(pao)(pao)光(guang)(guang)工作(zuo)(zuo)。在(zai)含(han)(han)(han)有鉻(ge)(ge)(ge)(ge)(ge)酐(gan)的(de)(de)溶(rong)液(ye)(ye)(ye)(ye)(ye)(ye)中(zhong)(zhong)(zhong)(zhong),加入(ru)明(ming)(ming)膠或(huo)(huo)甘(gan)油,它們能(neng)和鉻(ge)(ge)(ge)(ge)(ge)酐(gan)起強烈的(de)(de)還原(yuan)反(fan)(fan)應(ying),部分(fen)六(liu)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)轉(zhuan)變為(wei)三(san)(san)(san)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(Cr3+)。六(liu)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)是(shi)(shi)黃色(se)的(de)(de),三(san)(san)(san)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)是(shi)(shi)綠色(se)的(de)(de)。它們在(zai)電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)液(ye)(ye)(ye)(ye)(ye)(ye)中(zhong)(zhong)(zhong)(zhong)使(shi)溶(rong)液(ye)(ye)(ye)(ye)(ye)(ye)呈(cheng)(cheng)黃綠色(se)。這就是(shi)(shi)為(wei)什(shen)么(me)(me)通電(dian)(dian)(dian)(dian)(dian)(dian)處(chu)理(li)后才(cai)可電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)拋(pao)(pao)(pao)光(guang)(guang)。最(zui)佳的(de)(de)拋(pao)(pao)(pao)光(guang)(guang)質量(liang)是(shi)(shi)在(zai)電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)過程(cheng)的(de)(de)中(zhong)(zhong)(zhong)(zhong)間階段。在(zai)生(sheng)產(chan)過程(cheng)中(zhong)(zhong)(zhong)(zhong)電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)拋(pao)(pao)(pao)光(guang)(guang)液(ye)(ye)(ye)(ye)(ye)(ye)要(yao)保(bao)(bao)持黃綠色(se)。此(ci)時,根據化(hua)(hua)學分(fen)析數據,六(liu)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)與(yu)三(san)(san)(san)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)的(de)(de)配(pei)比(bi)(bi)是(shi)(shi):含(han)(han)(han)Cr6+30%,含(han)(han)(han)Cr3+70%.為(wei)了維持該配(pei)比(bi)(bi),可觀察電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)液(ye)(ye)(ye)(ye)(ye)(ye)的(de)(de)顏(yan)色(se),如(ru)果(guo)(guo)顏(yan)色(se)呈(cheng)(cheng)黃色(se)為(wei)主,表(biao)明(ming)(ming)電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)液(ye)(ye)(ye)(ye)(ye)(ye)含(han)(han)(han)Cr6+偏高(gao),可加入(ru)適(shi)量(liang)的(de)(de)明(ming)(ming)膠或(huo)(huo)甘(gan)油,使(shi)其部分(fen)六(liu)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)還原(yuan)為(wei)三(san)(san)(san)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge),或(huo)(huo)通過大(da)(da)陰極(ji)(ji)小陽極(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)產(chan)生(sheng)三(san)(san)(san)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)。如(ru)果(guo)(guo)顏(yan)色(se)呈(cheng)(cheng)深(shen)綠色(se),表(biao)明(ming)(ming)電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)液(ye)(ye)(ye)(ye)(ye)(ye)含(han)(han)(han)Cr3+高(gao)了,按比(bi)(bi)例適(shi)量(liang)加入(ru)用水溶(rong)解(jie)(jie)好的(de)(de)鉻(ge)(ge)(ge)(ge)(ge)酐(gan)溶(rong)液(ye)(ye)(ye)(ye)(ye)(ye),或(huo)(huo)通過大(da)(da)陽極(ji)(ji)小陰極(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)拋(pao)(pao)(pao)光(guang)(guang)液(ye)(ye)(ye)(ye)(ye)(ye),使(shi)三(san)(san)(san)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)部分(fen)轉(zhuan)變成六(liu)價(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)。同時可改善(shan)溶(rong)液(ye)(ye)(ye)(ye)(ye)(ye)的(de)(de)拋(pao)(pao)(pao)光(guang)(guang)質量(liang)。


14. 金(jin)屬拋除量


 如果電(dian)(dian)(dian)解(jie)拋(pao)(pao)(pao)光時陽極電(dian)(dian)(dian)流(liu)密度為20A/d㎡,時間為4min時,用工(gong)具(ju)金(jin)(jin)相顯微鏡觀測,不(bu)銹鋼零件(jian)(jian)的(de)(de)螺紋內徑的(de)(de)金(jin)(jin)屬(shu)拋(pao)(pao)(pao)除量(liang)為每分鐘約0.001mm,螺紋外徑的(de)(de)金(jin)(jin)屬(shu)拋(pao)(pao)(pao)除量(liang)為0.002mm,齒形基本無變化,僅齒的(de)(de)頂部(bu)略有拋(pao)(pao)(pao)鈍(dun)。陽極電(dian)(dian)(dian)流(liu)密度增加,其金(jin)(jin)屬(shu)拋(pao)(pao)(pao)除量(liang)呈比例增大。對于精密尺(chi)寸的(de)(de)不(bu)銹鋼零件(jian)(jian)的(de)(de)尺(chi)寸應考慮電(dian)(dian)(dian)化學拋(pao)(pao)(pao)光后的(de)(de)金(jin)(jin)屬(shu)拋(pao)(pao)(pao)除量(liang)(損耗)。


15. 電焊或熱處理(li)后零件(jian)的電化學拋(pao)光


 凡電(dian)焊或(huo)熱處理后的零件在電(dian)化學拋(pao)光時按兩次(ci)進行,第一次(ci)進槽拋(pao)光3~5min后取出,將已疏松(song)了(le)的焊渣(zha)和(he)熱處理氧化皮用金屬絲刷將它刷掉,或(huo)用小錘敲掉,再第二次(ci)進槽再拋(pao)光3~5min,可獲得較(jiao)好的效果。


16. 中和工序


 經(jing)過電化(hua)(hua)學拋(pao)光(guang)(guang)后的零(ling)件,如果不再進(jin)(jin)行(xing)(xing)后續加工,如電鍍(du)、著(zhu)色等其他(ta)工序(xu),要(yao)進(jin)(jin)行(xing)(xing)鈍化(hua)(hua)和中(zhong)和。中(zhong)和的作用是充分地(di)消(xiao)除在(zai)電化(hua)(hua)學拋(pao)光(guang)(guang)和鈍化(hua)(hua)后表(biao)(biao)面(mian)所吸附的酸(suan)性物質。中(zhong)和一般是在(zai)碳酸(suan)鈉20~30g/L的溶液(ye)中(zhong)進(jin)(jin)行(xing)(xing)的。路云鶴認為,經(jing)過電化(hua)(hua)學拋(pao)光(guang)(guang)后的零(ling)件表(biao)(biao)面(mian)有一層均勻的鈍化(hua)(hua)膜,可(ke)不需要(yao)再進(jin)(jin)行(xing)(xing)鈍化(hua)(hua)處理(li)。不銹(xiu)鋼零(ling)件電化(hua)(hua)學拋(pao)光(guang)(guang)后,經(jing)過40℃的溫水清(qing)洗(xi),再冷水清(qing)洗(xi),中(zhong)和并清(qing)洗(xi)后用壓縮空氣吹干,才(cai)可(ke)以有效地(di)避免殘留酸(suan)液(ye)腐蝕拋(pao)光(guang)(guang)表(biao)(biao)面(mian)。