釹鐵硼磁性材料磷化過程電位影響因素研究

1、20Feb .2005Vol .38No .2Materials Pr otecti on釹鐵硼磁性材料磷化過程電位影響因素研究王春明1,林偉2,趙鵬亮2(1.上海應(yīng)用技術(shù)學(xué)院化學(xué)工程系,上海200233;2.寧波韻升高科磁業(yè)有限工司,浙江寧波315040摘要為了研究釹鐵硼磁性材料的磷化機(jī)理,并研制釹鐵硼磁性材料的磷化劑,應(yīng)用電化學(xué)方法研究了游離酸度、溫度、促進(jìn)劑、表面活性劑對(duì)釹鐵硼磁性材料磷化動(dòng)力學(xué)行為的影響。結(jié)果表明,釹鐵硼磁性材料磷化動(dòng)力學(xué)的過程分為:金屬陽極溶解鈍化金屬陽極溶解磷化成膜4步;所形成的化學(xué)轉(zhuǎn)化膜并非單一的磷化膜,而是磷化和鈍化的混合膜;游離酸度、溫度以及促進(jìn)劑對(duì)釹鐵硼磷化

2、影響較大,過高的游離酸度(高于4.8和溫度(高于40將改變其磷化動(dòng)力學(xué)的過程,使磷化難以成膜或膜層粗糙;促進(jìn)劑能加速磷化的進(jìn)行,但氧化性過強(qiáng)的促進(jìn)劑(氯酸鈉只能增強(qiáng)釹鐵硼磁性材料表面的鈍化,而不能形成磷化膜。通過正交試驗(yàn)法,確定了釹鐵硼常溫磷化液的最佳配方和工藝條件:磷酸二氫鈉50g/L,磷酸12mL /L,鉬酸鈉0.5g /L,促進(jìn)劑N 0.2g/L,陰離子表面活性劑1.5mL /L,F A 1.5點(diǎn),T A 51點(diǎn),溫度30,時(shí)間5m in 。所得磷化鈍化膜薄而致密,耐腐蝕性能優(yōu)異。關(guān)鍵詞磷化;釹鐵硼磁性材料;電位中圖分類號(hào)T Q261.93文獻(xiàn)標(biāo)識(shí)碼A 文章編號(hào)1001-1560(200

3、502-0020-04收稿日期20040816基金項(xiàng)目上海市教委重點(diǎn)學(xué)科基金資助項(xiàng)目(Y040130前言釹鐵硼永磁材料自1983年問世以來,因其具有高飽和磁化強(qiáng)度、矯頑力及大的磁能積而被廣泛應(yīng)用于計(jì)算機(jī)、電子通訊、信息系統(tǒng)、微型電機(jī)、汽車、核磁共振、儀器儀表等高新產(chǎn)業(yè)。目前,我國(guó)燒結(jié)釹鐵硼的市場(chǎng)占有率約占全球總量的41%,具有很強(qiáng)的市場(chǎng)競(jìng)爭(zhēng)力。然而,釹鐵硼永磁材料是通過粉末冶金燒結(jié)成型的產(chǎn)品,結(jié)構(gòu)疏松、孔隙率高、表面狀態(tài)不佳。其中,釹含量36%38%,鐵含量60%,硼含量2%4%;釹含量很高,釹標(biāo)準(zhǔn)電極電位比鐵還要負(fù),在潮濕的空氣中極易被氧化,并與空氣中的酸性物質(zhì)發(fā)生強(qiáng)烈反應(yīng)而腐蝕。燒結(jié)釹鐵硼

4、是一種復(fù)雜的復(fù)相結(jié)構(gòu),以Nd 2Fe 14B 為基本磁性相(四方對(duì)稱相的永磁材料,在合金的晶界處存在富釹相NdO 2f .c .c,NdO 7h .c .p 以及Nd 5Fe 2B 6O 7富釹相片狀物,因而極易產(chǎn)生晶間腐蝕,形成釹的氧化物和氫化物并導(dǎo)致材料粉化,從而降低和破壞材料的磁性能。釹鐵硼永磁材料結(jié)構(gòu)特性所引起的耐腐蝕性差的缺陷,嚴(yán)重影響了其在高端磁性產(chǎn)品中的應(yīng)用。因此,對(duì)釹鐵硼磁性材料進(jìn)行表面處理,改善其表面狀態(tài),提高其抗腐蝕能力,對(duì)其應(yīng)用具有重要的意義。金屬表面的磷化處理能顯著提高金屬的耐腐蝕性,但將磷化處理技術(shù)應(yīng)用于釹鐵硼磁性材料的尚屬少見。本工作采用電化學(xué)方法,對(duì)釹鐵硼磁性材料

5、常溫磷化的<t 曲線表征進(jìn)行了研究,并探討了酸度、溫度、促進(jìn)劑、表面活性劑等對(duì)釹鐵硼磷化過程電位的影響。1試驗(yàn)1.1磷化工藝(1工藝流程:<25×5mm 的釹鐵硼永磁性材料脫脂熱水洗水洗除銹水洗水洗磷化水洗去離子水洗干燥。(2采用堿性脫脂劑脫脂,pH 值910,溫度5070,時(shí)間35m in 。(3采用150180mL /L 硫酸、3060mL /L硝酸和35g/L 硫脲為主的除銹液除銹和出光,室溫,時(shí)間2040s 。(4磷化基礎(chǔ)配方及工藝參數(shù):磷酸二氫鈉4555g/L,磷酸1015mL /L,鉬酸鈉0.40. 8材料保護(hù)2005年2月第38卷第2期21g/L,促進(jìn)劑0.

6、20.4g /L,F A (點(diǎn)1.02.0,T A (點(diǎn)4951,室溫,時(shí)間35m in 。1.2磷化過程電位測(cè)試(1研究電極與磷化的<t 曲線將待磷化處理的釹鐵硼永磁性材料進(jìn)行打磨拋光,再以16號(hào)金相砂紙依次精磨至表面光亮鏡面,制成研究電極,試驗(yàn)前以丙酮進(jìn)行除油。以飽和甘汞電極作參比電極,使用數(shù)字電位儀測(cè)定研究電極的電位,制作釹鐵硼永磁性材料磷化過程的<t 曲線圖1。(2游離酸度的影響按釹鐵硼磷化工藝流程和磷化基礎(chǔ)配方,改變磷化游離酸度,制作游離酸度影響的<t 曲線圖。(3溫度的影響按釹鐵硼磷化工藝流程和磷化基礎(chǔ)配方,改變磷化溫度,制作溫度影響的<t 曲線圖。(4促進(jìn)

7、劑的影響按釹鐵硼磷化工藝流程和磷化基礎(chǔ)配方,分別以鉬酸鈉、鎢酸鈉和氯酸鈉作為磷化促進(jìn)劑2,制作促進(jìn)劑影響的<t 曲線圖。(5表面活性劑的影響按釹鐵硼磷化工藝流程和磷化基礎(chǔ)配方,制作表面活性劑影響的<t 曲線圖。2結(jié)果與討論2.1釹鐵硼磷化<t 曲線與游離酸度的影響按基礎(chǔ)磷化配方,總酸度51點(diǎn),游離酸度(點(diǎn)分別為1.5,2.3,4.8,6.0,8.0,15.4,室溫下測(cè)得釹鐵硼磷化<t 曲線結(jié)果見圖1 。圖1游離酸度影響的磷化<t 曲線1.15.4點(diǎn)2.8.0點(diǎn)3.6.0點(diǎn)4.4.8點(diǎn)5.2.3點(diǎn)6.1.5點(diǎn)參照Ghail 提出的鋼鐵鋅系中溫磷化的<t 曲線五

8、步機(jī)理的假設(shè),由圖1可見:(1游離酸度為1.5點(diǎn)的釹鐵硼磷化<t 曲線在磷化時(shí)間內(nèi)可分為4區(qū)段,其基本形態(tài)與Ghail 的5區(qū)段劃分大體相似,為此釹鐵硼磁性材料常溫磷化的反應(yīng)機(jī)理如下:1區(qū)段電位負(fù)移,為金屬陽極溶解階段。2H 3P O 4+Fe Fe (H 2P O 42+H 26H 3P O 4+2Nd 2Nd (H 2P O 43+3H 22區(qū)段電位逐漸正移,此時(shí)鋼鐵表面開始形成金屬磷化膜Me 3(P O 42,構(gòu)成了非晶態(tài)底層既非晶態(tài)沉積。當(dāng)磷化在2區(qū)段時(shí)間結(jié)束時(shí)立即取出研究電極,用去離子水洗并干燥后,在金相顯微鏡下放大1000倍觀測(cè),沒有觀測(cè)到非晶態(tài)的磷化晶貌,而目測(cè)觀察釹鐵硼表

9、面呈明顯彩紅色轉(zhuǎn)化膜。用稀硝酸溶解轉(zhuǎn)化膜并用化學(xué)分析其成分,結(jié)果表明,轉(zhuǎn)化膜含有鐵離子、釹離子而無磷酸根離子。由此可見,彩紅色轉(zhuǎn)化膜并非磷酸鹽的非晶態(tài)沉積,而是化學(xué)鈍化膜2。此鈍化膜的形成導(dǎo)致釹鐵硼電極表面電阻增加,引起<t 曲線電位正移3。2區(qū)段形成的鈍化膜主要是由磷化基體材料不同引起的。釹鐵硼合金材料的化學(xué)活潑性遠(yuǎn)遠(yuǎn)大于鋼鐵材料,尤其是釹元素極易被氧化,在含有氯離子的介質(zhì)中,釹的電極電位比鐵的還負(fù)200mV 。釹鐵硼表面可形成無數(shù)Nd B ,Nd Fe 及Fe B 微電池反應(yīng),在酸性條件下易被氧化型的磷化促進(jìn)劑氧化,形成彩虹色鈍化膜。3區(qū)段電位再次負(fù)移,表明釹鐵硼的陽極溶解繼續(xù)進(jìn)行,

10、此區(qū)段反應(yīng)機(jī)理與Ghail 的第三步反應(yīng)相同。4區(qū)段電位緩慢正移,此時(shí)鈍化過程趨于動(dòng)態(tài)平衡階段。隨著磷化時(shí)間的延長(zhǎng),Fe 2+與Nd 3+濃度逐漸增加,釹鐵硼表面開始形成磷化膜5:3Fe (H 2P O 42Fe 3(P O 42+4H 3P O 4Nd (H 2P O 43NdP O 4+2H 3P O 4隨著磷化膜的逐步增厚,<t 曲線電極電位不斷正移,直至趨于平衡。綜上所述,釹鐵硼磁性材料的常溫磷化動(dòng)力學(xué)行為如下:金屬陽極溶解鈍化陽極溶解磷化成膜。所得化學(xué)轉(zhuǎn)化膜為一種鈍化磷化混合膜。(2當(dāng)游離酸度為1.5點(diǎn)時(shí),磷化的<t 曲線分為4區(qū)段,游離酸度為2.3點(diǎn)時(shí)磷化的<t

11、曲線也分為4區(qū)段,但各區(qū)段所需磷化時(shí)間均明顯增大且第4區(qū)段變化極為平緩。當(dāng)游離酸度逐步增大到4.8以上時(shí),磷化的<t 曲線只顯示3個(gè)區(qū)段,其動(dòng)力學(xué)行為發(fā)生明顯改變,即磷化過程為:金屬陽極溶解鈍化緩慢地陽極溶解。其中沒有磷化成膜的第4區(qū)段過程,金相顯微觀測(cè)(放大1000釹鐵硼磁性材料磷化過程電位影響因素研 究22Feb .2005Vol .38No .2Materials Pr otecti on倍也沒有觀測(cè)到磷化膜晶貌。由此可見,游離酸度對(duì)釹鐵硼磁性材料磷化的影響很大,隨著游離酸度的增大,磷化膜將難以形成。確定的最佳磷化酸度為F A 1.02.0點(diǎn),T A 4951點(diǎn)。2.2溫度的影響按

12、磷化基礎(chǔ)配方并添加1.5mL 陰離子表面活性劑,F A 1.5點(diǎn),T A 5.1點(diǎn),溫度分別為30、40和50,測(cè)定釹鐵硼磷化<t 曲線的結(jié)果見圖2 。圖2溫度影響的<t 曲線從圖2可以看出,30時(shí),磷化的<t 曲線分為典型的4區(qū)段,當(dāng)溫度升高至40及50時(shí),<t 曲線變?yōu)?區(qū)段,即金屬陽極溶解鈍化磷化成膜;而且第1、2區(qū)段的時(shí)間較30時(shí)大大縮短,第3區(qū)段的電位也較30時(shí)更加正移,可見溫度升高,磷化反應(yīng)加快,所得鈍化磷化膜變厚。磷化過程是一個(gè)吸熱反應(yīng),溫度升高將加速磷化反應(yīng)的進(jìn)行。但隨著溫度升高,磷化速度加快,所得磷化膜變得粗糙,孔隙率增大,降低了膜層的耐腐蝕性,也影響

13、了電鍍與電泳涂裝的配套性,同時(shí)又增加了能源的消耗。綜合各影響因素,確定磷化溫度范圍為2530。2.3促進(jìn)劑的影響按磷化基礎(chǔ)配方,F A 1.5點(diǎn),T A 5.1點(diǎn),分別以鉬酸鈉、氯酸鈉與鎢酸鈉為促進(jìn)劑,常溫下測(cè)定釹鐵硼磷化的<t 曲線,結(jié)果見圖3 。圖3促進(jìn)劑影響的<t 曲線圖3顯示,以鎢酸鈉作促進(jìn)劑的<t 曲線同鉬酸鈉一樣具有完整的4區(qū)段,但其鈍化區(qū)段與磷化成膜區(qū)段反應(yīng)更快,電位正移斜率更大,磷化反應(yīng)的電位差值也更大,可見氧化型促進(jìn)劑的氧化性越強(qiáng),磷化的促進(jìn)力就越大,磷化也越易成膜。氯酸鈉是鋼鐵鋅系磷化中傳統(tǒng)的促進(jìn)劑,使用廣泛,但圖3表明,以其作促進(jìn)劑的<t 曲線只分

14、為3區(qū)段,缺少重要的磷化成膜的第4區(qū)段。氯酸鈉是所選3種促進(jìn)劑中氧化性最強(qiáng)的,其氧化還原電位高達(dá)<0=1.451V 。在磷化過程中,氯酸鈉發(fā)生如下電極反應(yīng):Cl O -3+6e +6H +Cl -+3H 2O 產(chǎn)生的Cl -使釹鐵硼磁性材料中Nd 元素的電極電位負(fù)移,更易與氯酸鈉發(fā)生氧化還原反應(yīng),反應(yīng)的電位差E 很大。試驗(yàn)證實(shí),磷化開始5s 后釹鐵硼研究電極的電位便迅速正移,進(jìn)入鈍化區(qū)段;電位從-696mV 直至-541mV,正移155mV,時(shí)間達(dá)75s 。因此,在以氯酸鈉為促進(jìn)劑的磷化過程中,釹鐵硼表面發(fā)生的主要反應(yīng)是氧化鈍化反應(yīng),而非磷化成膜反應(yīng)。促進(jìn)劑對(duì)釹鐵硼磷化影響很大,選擇促進(jìn)

15、劑必須從促進(jìn)劑的氧化還原性4和磷化基本材料的結(jié)構(gòu)特性綜合評(píng)定5,6。圖3表明,鉬酸鈉與鎢酸鈉均是良好的促進(jìn)劑,但從磷化生產(chǎn)成本角度出發(fā),選擇鉬酸鈉為促進(jìn)劑。2.4表面活性劑的影響在磷化基礎(chǔ)配方中,添加不同含量的陰離子表面活性劑(F A 1.5點(diǎn),T A 51點(diǎn),常溫下測(cè)定釹鐵硼磷化的<t 曲線,結(jié)果見圖4 。圖4表面活性劑影響的<t 曲線圖4顯示,加入少量的表面活性劑可改變釹鐵硼磷化的過程電位,與圖1F A 為1.5點(diǎn)的<t 曲線相比,加入表面活性劑后,磷化成膜過程中電位正移的幅度大大增加。結(jié)果表明,加入表面活性劑前,磷化過程的電位差E =-623mV (-679mV =56

16、mV;加入表面活性劑后,磷化電位差E =-586mV (-701mV =115mV ,正移幅度增加2倍,加入表面活性劑有利于磷化的成膜釹鐵硼磁性材料磷化過程電位影響因素研 究材料保護(hù)2005年2月第38卷第2期23過程。表面活性劑并不直接參與成膜反應(yīng),但表面活性劑具有的潤(rùn)濕性和滲透性,降低了金屬表面的界面張力,增加了磷化液與金屬表面的潤(rùn)濕,加速了磷化過程中生成的氫氣從金屬表面逸出,起到了陰極去極化作用,促進(jìn)了磷化的進(jìn)行。從圖4還可以看出,隨著表面活性劑添加量的增加,磷化過程的電位正移也隨著增加,表明有利于磷化的進(jìn)行;當(dāng)添加量為1.5mL 與2.0mL 時(shí),其<t 曲線在磷化成膜區(qū)的形態(tài)已

17、近于重疊,表明此添加量應(yīng)該是飽和添加量,再增加表面活性劑的含量已不能增加效應(yīng)。為此,確定的表面活性劑最佳添加量為1.01.5mL /L,而臨界添加濃度為015mL /L 。3結(jié)論(1釹鐵硼磁性材料的常溫磷化<t 曲線研究表明,其磷化過程為:金屬陽極溶解鈍化金屬陽極再溶解磷化成膜4步機(jī)理;磷化所得化學(xué)轉(zhuǎn)化膜不是單一磷化膜,而是鈍化磷化混合膜;此混合轉(zhuǎn)化膜大大改善了釹鐵硼磁性材料表面狀態(tài),提高了釹鐵硼磁性材料的腐蝕性。(2促進(jìn)劑對(duì)釹鐵硼磷化過程電位影響很大,氧化型促進(jìn)劑的氧化性增強(qiáng),能促進(jìn)磷化的進(jìn)行,但過強(qiáng)的氧化劑只能增強(qiáng)釹鐵硼材料表面的鈍化,不利于磷化膜的形成。(3表面活性劑能起到陰極去極

18、化作用,添加少量的陰離子型表面活性劑有利于釹鐵硼磷化的進(jìn)行。(4游離酸度與溫度對(duì)釹鐵硼磷化過程電位影響較大,過高的游離酸度與溫度將改變其磷化過程,使磷化難以成膜或膜層粗糙、耐蝕性差。因此,確定優(yōu)化的酸度與溫度工藝參數(shù)十分重要。參考文獻(xiàn)1.常(低溫加速磷化過程中<t 曲線的研究.電鍍與環(huán)保,1994,14(7:1114.,李淑英.磷化促進(jìn)劑J .表面技術(shù),2002,31(6:13.3吳純素.化學(xué)轉(zhuǎn)化膜M .北京:化學(xué)工業(yè)出版社,1988.145146.4Gorecki G .Corr osi on Resistance of Ir on Phos phateCoatings and the

19、 I nfluence of Accelerat or Choice J .Metel Finishing,1995,193(3:1832.5松田茂樹.低溫磷化反應(yīng)J .實(shí)務(wù)表面技術(shù)(日,1988,35(1:2.6D.B.弗里曼,侯俊達(dá)譯.磷化與金屬預(yù)處理M .北京:國(guó)防工業(yè)出版,1988.1621.編輯:詹小玲關(guān)于在“中國(guó)熱處理行業(yè)協(xié)會(huì)樣本”中刊登會(huì)員單位產(chǎn)品及熱處理生產(chǎn)廠家介紹專頁的通知各會(huì)員單位:中國(guó)熱處理行業(yè)協(xié)會(huì)第五屆理事會(huì)已經(jīng)組成,協(xié)會(huì)組織構(gòu)成有很大變化,因此決定重新編印“中國(guó)熱處理行業(yè)協(xié)會(huì)樣本”,并在樣本中刊登會(huì)員單位產(chǎn)品及熱處理生產(chǎn)廠家介紹專頁,現(xiàn)將有關(guān)事宜通知如下:一、樣本內(nèi)容

20、1.中國(guó)熱處理行業(yè)協(xié)會(huì)簡(jiǎn)介。2.會(huì)員單位產(chǎn)品專頁。3.熱處理規(guī)范企業(yè)和熱處理生產(chǎn)廠家介紹專頁。二、關(guān)于會(huì)員單位產(chǎn)品及熱處理生產(chǎn)廠家介紹專頁的說明樣本中以“會(huì)員單位產(chǎn)品冠名”,刊登設(shè)備、材料、儀器(表、配件等企業(yè)產(chǎn)品專頁,會(huì)員單位一視同仁,優(yōu)先刊登“熱處理規(guī)范企業(yè)”、“質(zhì)量管理信得過企業(yè)”和“熱處理行業(yè)優(yōu)秀企業(yè)家”介紹,請(qǐng)刊登的企業(yè)提供媒體資料(文字、照片或磁盤、光盤等。熱處理行業(yè)規(guī)范企業(yè)和熱處理生產(chǎn)廠家需提供單位簡(jiǎn)介的文字資料,圖像資料可包括企業(yè)法人(負(fù)責(zé)人、廠房廠貌、車間、試驗(yàn)(檢驗(yàn)室等照片?？琴M(fèi)用見附表“在中國(guó)熱處理行業(yè)協(xié)會(huì)樣本中刊登會(huì)員單位產(chǎn)品及熱處理生產(chǎn)廠家介紹專頁回執(zhí)”。三、印刷數(shù)

21、量5000冊(cè)。四、發(fā)行范圍該樣本在全行業(yè)發(fā)送,主要是:1.用作與國(guó)內(nèi)外行業(yè)組織或企業(yè)交往的交換資料。2.在各種會(huì)議上作為資料發(fā)給代表。3.在國(guó)際、國(guó)內(nèi)展覽會(huì)中發(fā)送。4.發(fā)給會(huì)員單位。5.其他。五、截稿日期2005年4月底截稿。這是發(fā)行量較大的行業(yè)資料,歡迎企業(yè)踴躍刊登產(chǎn)品及熱處理生產(chǎn)廠家介紹的專頁。六、聯(lián)系方式通訊地址:北京海淀區(qū)學(xué)清路18號(hào)中國(guó)熱處理行業(yè)協(xié)會(huì)電話:010-*傳真:010-*電子郵箱:lxylbly1 郵政編碼:100083聯(lián)系人:劉西鷹鄭仲瑜中國(guó)熱處理行業(yè)協(xié)會(huì)釹鐵硼磁性材料磷化過程電位影響因素研 究erably with increasing Si O2content.Nam

22、ely,all the hardness,ben2 ding strength,resistance to water abs or p ti on,and resistance t o er o2 sioncorr osi on of the blended resins increased with increasing Si O2 content.Key words:blended resins;corr osion;er osi oncorrosion;silicon di2 oxide;p reparation;characterizationFactors Affecti n g

23、the Poten ti a l i n Phospha ti ng of NdFeB M ag2 neti c M a ter i a lWANG Chunm ing1,L I N W ei2,ZHAO Pengliang2(1.Shanghai Institute of App lied Technology,Shanghai200233; 2.N ingbo Yun2 sheng H ighTech Magnetics Co.L td,N ingbo315040,ChinaCail2 iao B aohu2005,38(2,2023(Ch.The influences of acidit

24、y, temperature,accelerator,and surfactant on the phosphating dynam ic behavior of NdFeB were investigated making use of electr ochem ical method s o as to investigate the phosphating mechanis m of and devel2 op phos phating agent for NdFeB magnetic material.The results showed that the dynam ic p roc

25、ess of NdFeB phosphating included f our step s,i.e.,the diss olving of anodic metal,the passivating,the redissolving of the anodic metal,and the phosphated fil m for m ing.The resulting chem ical conversion fil m was not a single phos phated fil m but a m ixture of the phos phatedpassivated coating.

26、The free acidity, temperature,and accelerator had obvi ous effects on the phosphating p r ocess of NdFeB.Overhigh acidity(more than418and tempera2 ture(more than40would cause change of the phos phating dy2 nam ic p rocess,which made it difficulty t o perf or m the phos phating or led to an increase

27、in the surface r oughness of the coating.Proper ac2 celerators could speed up the phos phating,however,the strong oxi2 dizing agent such as s odium chlorate as the accelerat or could only strengthen the surface passivation of the NdFeB and retarded the f or2 mati on of the phosphated coating.The op

28、ti m al for mula of the phos2 phating s olution and p r ocess conditions were deter m ined by orthogo2 nal test as following:50g/L s odium dihydrogen phosphate,12mL/ L phosphoric acid,015g/L s odium molybdate,012g/L accelerat or N,115mL/L ani on surfactant,free acidity115,total acidity51,30,and5m in

29、.The final target phosphatedpassivated coating was thin and dense and had excellent corrosion resistance.Key words:phos phating;NdFeB magnetic material;potential Prepara ti on of N iNanoA l2O3Com posite Electropla ti n g Ba th L I N W ensong,ZHANG L iyun,DU L in,ZHANG L inying,L I U Xiaoqing(College

30、 of Material Engineering,Shanghai University of Engineering Science,Shanghai200336,ChinaCailiao B aohu 2005,38(2,2426(Ch.The stable dispersion of nanoparticles in N i electr op lating bath is significant t o the p reparation of N inanop2 article composite coating.Thus a N inanoA l2O3composite electr

31、 o2 p lating bath was for mulated by introducing several kinds of surfac2 tants t o strengthen the dispersity of the nanoparticles therein.The in2 fluences of the surfactant content,the pH value,and the dis persing method on the dis persing stability of nanoA l2O3in the p lating bathwere studied usi

32、ng colori m etry.The size of the A l2O3nanoparticlesdispersed in the p lating bath was esti m ated using an atom ic force m i2croscope.It was f ound that the A l2O3nanoparticles in the m ixed bathsoluti on were p reci p itated after being st ored f or10h.It was feasible to increase the dis persing s

33、tability of the N inanoA l2O3composite p lating soluti on by intr oducing the dis persants such as ammonium polycarboxylate,triammonium citrate,and cetyl tri methyl ammonium br om ide and i m p lementing ultras onic stirring.The nanoA l2O3par2 ticulates dis persed in the composite bath had an averag

34、e size of63nm,which was much larger than that of the A l2O3nanoparticulatesas the raw material.Key words:composite p lating;N inanoA l2O3;nanometer particle; surfactant;dispersionA lka li n e Z i n ca te Conti n uous Z i n c Pla ti n g Process for Steel Sheet Z UO Zhengxun,MA Chong(Nanhai Fengfan Re

35、search I nstitute of Surface Technol ogy,Foshan528226,ChinaCailiaoB aohu2005, 38(2,2730(Ch.Conventional alkaline cyanide zinc p lating p r ocess was compulsively restricted f or its em ission of t oxic and hurt2 ful substances and har m to the envir onment and human being.There2 fore,it is i m perat

36、ive to devel op cyanidefree zinc p lating p rocess s o as to meet with the increased demand f or galvanized steel sheet in our country.Thus the alkaline zincate continuous zinc p lating technologyfor steel sheet was investigated,with the emphasis being p laced on the effects of the bath composition

37、and p r ocess conditi ons on the cur2 rent efficiency.The thr owing power of the p lating s olution was tested using Hulls cell8points thickness method,and the adhesi on strength of the coating was exam ined by heating and shock cooling test.Moreover,the p retreat ment and posttreat ment p r ocesses

38、 for the steel sheet subject to continuous zinc p lating were also discussed. Results showed that the alkaline zincate p lating p rocess had many ad2 vantages over conventi onal alkaline cyanide zinc p lating p r ocess,in2 cluding high current efficiency,good thr owing power,and strong ad2 hesi on s

39、trength of the coating.The resulting galvanized steel sheet can be readily posttreated by passivation and p recoating.Key words:continuous p lating;steel sheet;zinc p lating;zincatePr i m ary Study on Process of N ickelPhosphorus A lloy Electro2 pl a ti n gZHANG Chunli1,ZHOU Q i1,ZHAO Ping2(1.Colleg

40、e of Chem ical Engineering,Shenyang L igong University,Shenyang110168; 2. Fuel Cell R&D Center,Dalian I nstitute of Chem ical Physics,Chi2 nese Academy of Sciences,Dalian116023,ChinaCailiao B aohu 2005,38(2,3133(Ch.Compared to electr oless nickelphos2 phorus p lating,N iP all oy electr op lating

41、 has the advantages such as rap id deposit rate,l ow bath temperature,high bath stability,thick deposit,and low cost.However,N iP all oy electrop lating has the disadvantages including unstable perfor mance of the bath s olution and deposit and l ow current efficiency as compared with general metal

42、e2 lectrop lating.Thus a new bath mainly composed of nickel sulfate, nickel chl oride,s odium hypophosphite,boric acid,and sodium flu2 oride was f or mulated,based on the comparison of several N iP all oy electrop lating s olutions using neutral salt sp ray test,i m mersion corr o2 sion test,and the

43、 measurement of the porosity,adhesi on,and hard2 ness of the N iP all oy coating.The influence of the NaH2PO2content and cathode current density on the hardness and corrosion resistance of the N iP alloy coating was studied.Results showed that the corr o2 sion resistance of the N iP alloy coating in

44、creased with increasing NaH2P O2content.The asp lated N iP alloy coating with the largest hardness of492HV was p repared fr om the bath containing50g/LNaH2P O2at a cathode current density of5A/dm2.The N iP all oy coating containing12.1%P(mass fracti ondeposited at a rate of 54m/h had a hardness of91

45、6HV after p r oper heat treat m ent.The newly for mulated bath was superior to those f or conventi onal metal e2 lectrop lating in ter m s of the bright and fine mor phology,good adhe2 sion,high hardness,and rap id deposit velocity of the target N iP al2 loy coating.Key words:electr op lating;N iP all oy;s odium hypop