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. 在使用過(guo)(guo)程中需要經(jing)常(chang)測量(liang)電(dian)化學(xue)拋光(guang)液(ye)的(de)相(xiang)對密(mi)度。如(ru)果相(xiang)對密(mi)度小于配(pei)(pei)方規定(ding)(ding)值(zhi),表明電(dian)化學(xue)拋光(guang)液(ye)含水(shui)過(guo)(guo)多(duo),可(ke)用蒸發法(fa)將溶(rong)液(ye)加熱至80℃以上,將多(duo)余(yu)水(shui)分除去,體積不足部分可(ke)按配(pei)(pei)方比例補充磷酸和硫(liu)酸。在工(gong)件(jian)進入電(dian)化學(xue)拋光(guang)槽前,最好(hao)將工(gong)件(jian)上所附著的(de)水(shui)分瀝干或吹干。如(ru)果相(xiang)對密(mi)度太高,超過(guo)(guo)配(pei)(pei)方規定(ding)(ding)值(zhi),表示水(shui)分過(guo)(guo)少,要適當(dang)補充少量(liang)水(shui),使相(xiang)對密(mi)度降至規定(ding)(ding)值(zhi)。有條件(jian)的(de)最好(hao)按周期化驗分析溶(rong)液(ye),根據結果及(ji)時(shi)進行調(diao)整(zheng)。
3. 溶液的老化
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(qing)理(li)陰極(ji)鉛板
在拋(pao)(pao)光過程中陰(yin)極鉛板(ban)表(biao)面會(hui)沉積出一層厚(hou)厚(hou)的鐵、鎳等雜質(zhi),影響陰(yin)極表(biao)面導(dao)電(dian),導(dao)致(zhi)電(dian)流(liu)下(xia)降,使拋(pao)(pao)光表(biao)面的陽極電(dian)流(liu)密度也上(shang)不去,嚴重影響拋(pao)(pao)光質(zhi)量。因此,要(yao)及時(shi)將陰(yin)極板(ban)上(shang)的沉積物除(chu)去,有時(shi)形成硬質(zhi)厚(hou)膜,要(yao)強力敲打才(cai)能除(chu)下(xia),最后沖洗(xi)干(gan)凈(jing),以保(bao)持整個電(dian)路(lu)通暢。
5. 陰極與陽極面積比
陰極面(mian)積(ji)控制在陽極面(mian)積(ji)的(de)(de)1/2~1/3.5.在此情況下,可以防止三價鉻(ge)的(de)(de)增(zeng)長,過多的(de)(de)三價鉻(ge)在陽極表(biao)面(mian)被氧化(hua)成(cheng)六價鉻(ge)。三價鉻(ge)含量過多,易使拋光液老(lao)化(hua)。
6. 陰陽極之間的(de)極距
陰極與陽極之(zhi)間(jian)的距離過(guo)(guo)大、電(dian)阻增(zeng)大,電(dian)能消耗增(zeng)大,溶液容(rong)易升溫,影響拋光(guang)質量。距離過(guo)(guo)小(xiao),易造成短路打(da)火(huo),燒黑(hei)制品。陰極與陽極之(zhi)間(jian)的距離以100~300mm為宜。
7. 象形陰極
對拋光一(yi)些復雜的(de)大型工(gong)件(jian),可(ke)制作象(xiang)形陰(yin)(yin)極,以(yi)保持陽(yang)極電流分布均勻(yun),特別是(shi)對內(nei)腔(qiang)工(gong)件(jian),有適(shi)當(dang)的(de)象(xiang)形陰(yin)(yin)極安置(zhi)在(zai)內(nei)腔(qiang)中,才(cai)能使內(nei)腔(qiang)各部(bu)位拋光一(yi)致。
8. 進出槽要切斷電(dian)源
在電(dian)化(hua)學拋(pao)光時,由(you)于電(dian)流密度(du)較高(gao),給電(dian)流較大,因此,工件在進出拋(pao)光槽時,要先(xian)切斷電(dian)源,不可帶電(dian)掛(gua)或摘夾具,以防止產(chan)生電(dian)火花,引起電(dian)解產(chan)生,并會使聚集(ji)在槽面上的氫氣和氧氣混合氣發生爆炸。
9. 控制槽(cao)液溫(wen)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(shi)的陽極電(dian)流密度
不銹鋼零件電(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)學(xue)拋(pao)(pao)(pao)(pao)光(guang)(guang)時,陽(yang)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)密(mi)(mi)(mi)度(du)與金(jin)屬的溶解幾(ji)乎呈(cheng)(cheng)正比。只(zhi)有選擇好陽(yang)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)密(mi)(mi)(mi)度(du),并控制(zhi)在(zai)(zai)一定的陽(yang)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)位區間,才能獲得(de)(de)良好的電(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)學(xue)拋(pao)(pao)(pao)(pao)光(guang)(guang)質量,陽(yang)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)密(mi)(mi)(mi)度(du)的最(zui)佳(jia)值,要根據不同的電(dian)(dian)(dian)(dian)(dian)(dian)解液配方(fang),通過(guo)實際拋(pao)(pao)(pao)(pao)光(guang)(guang),觀察(cha)拋(pao)(pao)(pao)(pao)光(guang)(guang)所得(de)(de)最(zui)佳(jia)值確(que)定。在(zai)(zai)合適(shi)的陽(yang)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)密(mi)(mi)(mi)度(du)下,根據黏膜(mo)理論,微觀表面(mian)凸(tu)出(chu)部位優先溶解,有利于整平精飾表面(mian)。陽(yang)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)密(mi)(mi)(mi)度(du)過(guo)小(xiao),零件表面(mian)發(fa)生一般(ban)的陽(yang)極(ji)溶解,起不到拋(pao)(pao)(pao)(pao)光(guang)(guang)效果。陽(yang)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)密(mi)(mi)(mi)度(du)過(guo)大,黏膜(mo)被(bei)擊穿,氧氣(qi)猛烈析出(chu)呈(cheng)(cheng)氣(qi)流(liu)(liu)(liu)狀,表面(mian)過(guo)熱,導致電(dian)(dian)(dian)(dian)(dian)(dian)拋(pao)(pao)(pao)(pao)光(guang)(guang)液擴(kuo)散加(jia)劇,黏膜(mo)被(bei)破壞(huai),不復存(cun)在(zai)(zai),發(fa)生電(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)學(xue)腐(fu)蝕。所以在(zai)(zai)電(dian)(dian)(dian)(dian)(dian)(dian)拋(pao)(pao)(pao)(pao)光(guang)(guang)過(guo)程中必須(xu)控制(zhi)陽(yang)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)密(mi)(mi)(mi)度(du)在(zai)(zai)最(zui)佳(jia)值,也(ye)就是在(zai)(zai)確(que)定的工藝范圍內。
11. 陽極(ji)移動(dong)
陽(yang)(yang)極移(yi)動使陽(yang)(yang)極溶(rong)解產物(wu)加快擴散(san)出(chu)去(qu),起到攪拌(ban)作用,有效地排除陽(yang)(yang)極表(biao)面滯(zhi)留的氣泡,避免產生的氣流生成(cheng)條(tiao)紋,防止(zhi)局部過熱造成(cheng)表(biao)面過腐蝕。陽(yang)(yang)極移(yi)動有助于(yu)提(ti)高(gao)陽(yang)(yang)極電(dian)流密度,提(ti)高(gao)不銹鋼零件的電(dian)化學(xue)拋光表(biao)面質量(liang)。
12. 氯(lv)離子的危害
在電化學拋光液中(zhong)不(bu)(bu)允許(xu)有活性(xing)氯(lv)(lv)離(li)(li)子(zi)(zi)存在,氯(lv)(lv)離(li)(li)子(zi)(zi)能破(po)壞電化學拋光中(zhong)表(biao)面形(xing)成(cheng)(cheng)的(de)保護(hu)性(xing)黏膜,使不(bu)(bu)銹鋼表(biao)面形(xing)成(cheng)(cheng)過腐蝕性(xing)的(de)麻點。氯(lv)(lv)離(li)(li)子(zi)(zi)可在陽極高電流密(mi)度上(shang)氧化成(cheng)(cheng)氯(lv)(lv)氣逸出而(er)除去。氯(lv)(lv)離(li)(li)子(zi)(zi)的(de)來(lai)源可能是用(yong)鹽(yan)酸(suan)酸(suan)洗(xi)后未洗(xi)凈而(er)帶入槽液,或(huo)原料中(zhong)的(de)不(bu)(bu)純物氯(lv)(lv)離(li)(li)子(zi)(zi)引入。
13. 六價(jia)鉻和三價(jia)鉻的最佳配比
在(zai)(zai)電(dian)(dian)(dian)化(hua)(hua)學(xue)拋(pao)光(guang)(guang)液(ye)(ye)(ye)(ye)(ye)中(zhong)(zhong)(zhong)六(liu)(liu)(liu)價(jia)(jia)(jia)(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)有氧(yang)化(hua)(hua)性,對不銹鋼(gang)表(biao)(biao)面(mian)(mian)起鈍化(hua)(hua)保護作用,三(san)(san)(san)(san)(san)價(jia)(jia)(jia)(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)對維(wei)護電(dian)(dian)(dian)拋(pao)光(guang)(guang)有作用。新配(pei)成(cheng)(cheng)的(de)(de)(de)(de)(de)電(dian)(dian)(dian)拋(pao)光(guang)(guang)液(ye)(ye)(ye)(ye)(ye)如果沒(mei)有化(hua)(hua)學(xue)反應(ying)產生(sheng)三(san)(san)(san)(san)(san)價(jia)(jia)(jia)(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge),還不能獲得良好(hao)的(de)(de)(de)(de)(de)拋(pao)光(guang)(guang)表(biao)(biao)面(mian)(mian)。只有當電(dian)(dian)(dian)解到溶(rong)(rong)液(ye)(ye)(ye)(ye)(ye)中(zhong)(zhong)(zhong)有一定量的(de)(de)(de)(de)(de)三(san)(san)(san)(san)(san)價(jia)(jia)(jia)(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)存(cun)在(zai)(zai)時(shi),才能出現理想的(de)(de)(de)(de)(de)拋(pao)光(guang)(guang)表(biao)(biao)面(mian)(mian)。如果配(pei)方中(zhong)(zhong)(zhong)加(jia)有鉻(ge)(ge)(ge)(ge)(ge)(ge)酐(gan)(gan),即六(liu)(liu)(liu)價(jia)(jia)(jia)(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge),通(tong)(tong)過(guo)電(dian)(dian)(dian)解反應(ying),在(zai)(zai)陰極(ji)(ji)上(shang)產生(sheng)氫氣還原部(bu)分六(liu)(liu)(liu)價(jia)(jia)(jia)(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)成(cheng)(cheng)為三(san)(san)(san)(san)(san)價(jia)(jia)(jia)(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge);如果配(pei)方中(zhong)(zhong)(zhong)沒(mei)有鉻(ge)(ge)(ge)(ge)(ge)(ge)酐(gan)(gan),則三(san)(san)(san)(san)(san)價(jia)(jia)(jia)(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)要(yao)靠陽極(ji)(ji)溶(rong)(rong)解不銹鋼(gang)所(suo)含的(de)(de)(de)(de)(de)鉻(ge)(ge)(ge)(ge)(ge)(ge)而得。這(zhe)就(jiu)是(shi)(shi)為什(shen)么(me)新配(pei)的(de)(de)(de)(de)(de)電(dian)(dian)(dian)解拋(pao)光(guang)(guang)液(ye)(ye)(ye)(ye)(ye)要(yao)充分電(dian)(dian)(dian)解后(hou)才能進行正常的(de)(de)(de)(de)(de)拋(pao)光(guang)(guang)工作。在(zai)(zai)含有鉻(ge)(ge)(ge)(ge)(ge)(ge)酐(gan)(gan)的(de)(de)(de)(de)(de)溶(rong)(rong)液(ye)(ye)(ye)(ye)(ye)中(zhong)(zhong)(zhong),加(jia)入明(ming)膠或甘(gan)油,它們(men)能和鉻(ge)(ge)(ge)(ge)(ge)(ge)酐(gan)(gan)起強(qiang)烈(lie)的(de)(de)(de)(de)(de)還原反應(ying),部(bu)分六(liu)(liu)(liu)價(jia)(jia)(jia)(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)轉(zhuan)變為三(san)(san)(san)(san)(san)價(jia)(jia)(jia)(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)(Cr3+)。六(liu)(liu)(liu)價(jia)(jia)(jia)(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)是(shi)(shi)黃色(se)(se)的(de)(de)(de)(de)(de),三(san)(san)(san)(san)(san)價(jia)(jia)(jia)(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)是(shi)(shi)綠色(se)(se)的(de)(de)(de)(de)(de)。它們(men)在(zai)(zai)電(dian)(dian)(dian)解液(ye)(ye)(ye)(ye)(ye)中(zhong)(zhong)(zhong)使溶(rong)(rong)液(ye)(ye)(ye)(ye)(ye)呈黃綠色(se)(se)。這(zhe)就(jiu)是(shi)(shi)為什(shen)么(me)通(tong)(tong)電(dian)(dian)(dian)處理后(hou)才可(ke)電(dian)(dian)(dian)解拋(pao)光(guang)(guang)。最佳(jia)的(de)(de)(de)(de)(de)拋(pao)光(guang)(guang)質(zhi)量是(shi)(shi)在(zai)(zai)電(dian)(dian)(dian)解過(guo)程的(de)(de)(de)(de)(de)中(zhong)(zhong)(zhong)間階(jie)段。在(zai)(zai)生(sheng)產過(guo)程中(zhong)(zhong)(zhong)電(dian)(dian)(dian)解拋(pao)光(guang)(guang)液(ye)(ye)(ye)(ye)(ye)要(yao)保持(chi)(chi)黃綠色(se)(se)。此時(shi),根(gen)據(ju)化(hua)(hua)學(xue)分析(xi)數據(ju),六(liu)(liu)(liu)價(jia)(jia)(jia)(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)與三(san)(san)(san)(san)(san)價(jia)(jia)(jia)(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)的(de)(de)(de)(de)(de)配(pei)比是(shi)(shi):含Cr6+30%,含Cr3+70%.為了維(wei)持(chi)(chi)該配(pei)比,可(ke)觀察電(dian)(dian)(dian)解液(ye)(ye)(ye)(ye)(ye)的(de)(de)(de)(de)(de)顏色(se)(se),如果顏色(se)(se)呈黃色(se)(se)為主(zhu),表(biao)(biao)明(ming)電(dian)(dian)(dian)解液(ye)(ye)(ye)(ye)(ye)含Cr6+偏高,可(ke)加(jia)入適(shi)量的(de)(de)(de)(de)(de)明(ming)膠或甘(gan)油,使其部(bu)分六(liu)(liu)(liu)價(jia)(jia)(jia)(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)還原為三(san)(san)(san)(san)(san)價(jia)(jia)(jia)(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge),或通(tong)(tong)過(guo)大陰極(ji)(ji)小(xiao)陽極(ji)(ji)電(dian)(dian)(dian)解產生(sheng)三(san)(san)(san)(san)(san)價(jia)(jia)(jia)(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)。如果顏色(se)(se)呈深綠色(se)(se),表(biao)(biao)明(ming)電(dian)(dian)(dian)解液(ye)(ye)(ye)(ye)(ye)含Cr3+高了,按比例適(shi)量加(jia)入用水溶(rong)(rong)解好(hao)的(de)(de)(de)(de)(de)鉻(ge)(ge)(ge)(ge)(ge)(ge)酐(gan)(gan)溶(rong)(rong)液(ye)(ye)(ye)(ye)(ye),或通(tong)(tong)過(guo)大陽極(ji)(ji)小(xiao)陰極(ji)(ji)電(dian)(dian)(dian)解拋(pao)光(guang)(guang)液(ye)(ye)(ye)(ye)(ye),使三(san)(san)(san)(san)(san)價(jia)(jia)(jia)(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)部(bu)分轉(zhuan)變成(cheng)(cheng)六(liu)(liu)(liu)價(jia)(jia)(jia)(jia)(jia)鉻(ge)(ge)(ge)(ge)(ge)(ge)。同時(shi)可(ke)改(gai)善溶(rong)(rong)液(ye)(ye)(ye)(ye)(ye)的(de)(de)(de)(de)(de)拋(pao)光(guang)(guang)質(zhi)量。
14. 金(jin)屬(shu)拋(pao)除量
如果電解拋(pao)(pao)光時(shi)(shi)陽極電流密度為(wei)20A/d㎡,時(shi)(shi)間(jian)為(wei)4min時(shi)(shi),用工具金(jin)相顯微鏡觀(guan)測,不銹鋼(gang)零件的(de)(de)(de)螺紋內徑的(de)(de)(de)金(jin)屬(shu)拋(pao)(pao)除量(liang)為(wei)每分鐘約(yue)0.001mm,螺紋外徑的(de)(de)(de)金(jin)屬(shu)拋(pao)(pao)除量(liang)為(wei)0.002mm,齒形基本無(wu)變化,僅齒的(de)(de)(de)頂部略有拋(pao)(pao)鈍(dun)。陽極電流密度增加,其金(jin)屬(shu)拋(pao)(pao)除量(liang)呈比例(li)增大。對(dui)于精(jing)密尺(chi)寸的(de)(de)(de)不銹鋼(gang)零件的(de)(de)(de)尺(chi)寸應考慮電化學拋(pao)(pao)光后的(de)(de)(de)金(jin)屬(shu)拋(pao)(pao)除量(liang)(損耗)。
15. 電焊(han)或(huo)熱處理后零(ling)件的電化學(xue)拋光
凡電(dian)焊或熱(re)處理(li)后(hou)的(de)零件在電(dian)化學拋(pao)光時按(an)兩次進(jin)行,第一次進(jin)槽(cao)拋(pao)光3~5min后(hou)取出,將已疏松(song)了(le)的(de)焊渣和(he)熱(re)處理(li)氧化皮用金(jin)屬絲刷將它刷掉(diao),或用小錘敲掉(diao),再(zai)第二次進(jin)槽(cao)再(zai)拋(pao)光3~5min,可獲(huo)得(de)較好的(de)效(xiao)果。
16. 中和工序
經(jing)過(guo)電(dian)化(hua)學拋(pao)光(guang)(guang)(guang)后(hou)(hou)的零件(jian),如(ru)(ru)果(guo)不(bu)再(zai)進(jin)行(xing)后(hou)(hou)續(xu)加(jia)工,如(ru)(ru)電(dian)鍍、著色等其他工序(xu),要進(jin)行(xing)鈍化(hua)和中和。中和的作(zuo)用是充分地(di)消除在電(dian)化(hua)學拋(pao)光(guang)(guang)(guang)和鈍化(hua)后(hou)(hou)表(biao)(biao)面(mian)所吸(xi)附的酸(suan)性(xing)物(wu)質。中和一(yi)般(ban)是在碳(tan)酸(suan)鈉20~30g/L的溶液中進(jin)行(xing)的。路(lu)云鶴認為,經(jing)過(guo)電(dian)化(hua)學拋(pao)光(guang)(guang)(guang)后(hou)(hou)的零件(jian)表(biao)(biao)面(mian)有一(yi)層均(jun)勻的鈍化(hua)膜(mo),可不(bu)需要再(zai)進(jin)行(xing)鈍化(hua)處(chu)理(li)。不(bu)銹鋼零件(jian)電(dian)化(hua)學拋(pao)光(guang)(guang)(guang)后(hou)(hou),經(jing)過(guo)40℃的溫水(shui)清(qing)(qing)洗(xi),再(zai)冷(leng)水(shui)清(qing)(qing)洗(xi),中和并清(qing)(qing)洗(xi)后(hou)(hou)用壓(ya)縮空氣吹干,才可以有效(xiao)地(di)避免殘(can)留酸(suan)液腐蝕拋(pao)光(guang)(guang)(guang)表(biao)(biao)面(mian)。


 
		