55
姜力强1
，陈巧玲1
，李润锋2
，齐方良
1
(1.浙江工业大学化学工程与材料学院，浙江杭州310014;2.杭州精正磁业有限公司，浙江杭州311612)
国家杜马[摘 要] 复合钕铁硼磁体在高温潮湿环境下易被腐蚀，因而需要涂层保护。研究了复合永磁 体基体性能和阴极电泳环氧树脂工艺参数对复合钕铁硼/铁氧体黏结磁体的电泳涂漆质量的影响，通过QJ57直流电阻电桥测试了磁体的电阻，采用盐雾试验和湿热试验测试了涂层耐腐蚀性能。结果表明，复合黏结磁体中锶铁氧体磁粉含量质量分数超过30%时，电阻率急剧升高，难以获得优良的涂层。采用EE
D 2060M 环氧树脂电泳漆，在漆液温度28～32℃，电压120～180V，固化温度150～170℃的电泳工艺条件下，在锶铁氧体含量质量分数少于30%的磁体表面可包覆上一层致密、光滑的，且具有优异耐蚀性能的涂层。
[关键词] 阴极电泳;；钕铁硼；锶铁氧体[]A [文章编号]1001-1560(2006)04-0055-03
[收稿日期] 20051009
0 前 言
由于快淬钕铁硼磁粉特别是MQ 磁粉的价格较贵，在很大程度上影响了黏结钕铁硼磁体的广泛
应用，而复合黏结钕铁硼永磁体可以在低价位、低温度系数、磁性能设计等方面获得突破，因此，将铁氧体或其他磁粉与钕铁硼磁粉混合制成的复合黏结钕铁硼磁体备受关注。但是，黏结钕铁硼磁体在高温、潮湿环境中使用时容易氧化生锈，腐蚀后的磁体磁性能大幅下降，不仅影响制品外观，而且严
重影响磁体的使用性能和其应用领域的拓展[1]
。
目前，通常采用表面涂层的方法来提高黏结钕铁硼复合永磁体的耐腐蚀性能，其涂层种类主要有
金属涂层[2,3]、聚合物涂层[4,5]和复合涂层[6]
。其中聚合物涂层中阴极电泳环氧树脂以其低渗水性、低污染、高抗化学物质侵蚀性等特点成为当前黏结钕铁硼复合永磁体防护最常用的方法。国内外对阴极电泳工艺已有很多研究，但该涂层在黏结钕铁硼/铁氧体复合磁体的应用介绍却很少。本工作针对黏结钕铁硼磁体的特点，研究了复合永磁体本身及电泳工艺参数对涂层外观、磁体耐蚀性的影响。
1 试 验
1.1试 样
试验采用麦格昆磁有限公司的快淬NdFe B 磁
粉(MQP 21627)和霸菱磁材有限公司提供的S ME 27S 各向同性锶铁氧体磁粉，黏结剂为北京航空材
料研究所的SY 2TG1环氧树脂(含有一定的固化剂
和促进剂)，电泳漆为杭州优立化工的EED 2060M 环氧树脂电泳漆，其他试剂均为分析纯。
将NdFe B 磁粉与锶铁氧体磁粉分别以1ζ0,9ζ1,8ζ2,7ζ3,6ζ4,5ζ5,4ζ6,3ζ7的质量比
进行共混，然后用含磁粉总质量1%的KH550硅烷偶联剂溶液包覆处理并干燥后与SY 2TG1环氧树脂以97ζ3的质量比混合，其溶剂为丙酮。将上述干燥的复合磁粉压制成<18mm ×14mm ×6mm 的圆环，并加热固化成黏结钕铁硼/铁氧体复合永磁体试样。磁体经前处理后进行电泳涂覆，整个工艺流程为：工件抛光→除油→热水洗→冷水洗→除锈(无锈可省略该工序)→冷水洗→表面调整→磷化→冷水洗→纯水洗→阴极电泳→纯水循环洗→纯水淋洗→干燥→固化→检验。
将工件放入ZHXX M 280型抛光机中进行倒角，时间20～30m in；清洗除油选用LCX 252常温水基清洗剂；用稀酸溶液除锈；常温下进行表调；于50～55℃之间对磁体进行磷化。前处理各工序的
参数见表1。
在工件进入电泳槽前，检查除油和磷化质量，杜绝除油不净或磷化上膜不全的工件入槽电泳。1.2 电泳工艺参数
固体15%～25%,pH 值5.5～6.5,
电泳电压
© 1994-2009 China Academic Journal Electronic Publishing House. All rights reserved. wwwki
56
表1 前处理各工序参数
参数槽液浓度/%
玩3Q体会温度/℃时间/s
除油 1.50～2.00室温120～180除锈(酸)8.00～10.00室温～4030～60表调(钛盐)0.20～0.30
室温
30～40磷化(市售)
磷化剂0.50～3.5050～55
120～180
促进剂0.05～0.20
60～200V，电泳时间1～3m in，漆液温度20～35
℃，电导率(1000±400)μg/c m ，固化温度150～170℃，固化时间20～30m in 。
2 结果与讨论
2.1 基体
磁体的电阻率和表面状况是影响电泳涂层质量的两个重要因素。阴极电泳树脂漆一般都带有碱性基团，经有机酸中和后在电场作用下发生电离、电泳、电沉积、电渗4个电化学反应过程，从而在磁体表面电沉积涂层。复合磁体本身电阻率的高低与电阻率分布的均匀情况将直接影响涂层的质量，电阻率低和分布均匀，电化学反应就能顺利进行，且在磁体表面生成均匀、光滑的涂层。当漆膜的电阻达到一定值电场，电流趋于零，便可结束电泳操作。
通过H itachiS 24700场发射扫描电镜观察黏结钕铁硼/铁氧体断面的微观形貌(见图1)。其中灰、片状的为快淬NdFe B 磁粉，黑的为铁氧体磁粉，白的为环氧树脂。环氧树脂与铁氧体的电阻率都很高，它们的存在一方面使磁体表面的电阻率升高，另一方面容易导致磁体电阻率分布不均匀，特别是在有铁氧体磁粉存在的情况下，极易导致电泳涂层厚度不均
。
图1 黏结磁体微观形貌
根据G B1424—96，用QJ57型直流电阻电桥测
量上一步所制得的磁体的电阻，并根据公式ρ=
R ×S
L
计算电阻率。锶铁氧体含量对复合磁体电阻率的影响见图2
。
图2 永磁铁氧体含量对复合磁体电阻率的影响
由图2可知，当添加的铁氧体含量较小时(≤
30%)，复合磁体电阻率仅略有增加，但超过30%后，电阻率急剧上升，含50%铁氧体的复合磁体的电阻率与含30%的电阻率相比提高了近50倍。对涂层观察发现，电阻率的测量结果和对复合磁体进行阴极电泳试验的结果基本一致。铁氧体含量小于30%的复合磁体进行阴极电泳可以获得光滑的涂
层，而铁氧体含量为40%的复合磁体则阴极电泳效果很差，涂层包覆不均匀或出现较多麻点，这时就得考虑改用浸涂、静电喷涂等其他表面处理工艺。另外，快淬钕铁硼磁粉的颗粒度一般都在50～300μm 之间，粒度跨越较大，如不进行粒度筛选，压制出的磁体表面比较粗糙，不利于电泳时生成优质的涂层。在保证磁体磁性能要求的前提下，在复合钕铁硼磁体中加入铁氧体磁粉(粒度在l μm 左右)，可降低磁体的生产成本。2.2 工艺参数
2.2.1 漆液温度
邓拓吴晗廖沫沙漆液温度上升，电流值也随之增大，电沉积量也跟着增加。这是因为槽液升高时水溶性树脂粒子的布朗运动加剧而使漆液黏度下降，树脂电泳运动速度加快，电沉积速度也加快，但温度过高可导致过量沉积而出现桔皮，甚至导致水的电解反应加剧而使漆膜出现针孔等缺陷。如温度超过35℃，虽然沉积
速度加快，但漆膜过于粗糙，烘干后会产生波浪状堆积，其严重的“边角效应”会改变磁体的公差尺寸，影响磁体在正常工作中的性能；此外，高温还会使漆液的溶剂挥发加快或发生聚合反应使漆液变质。漆液温度低于20℃，虽可得到细致
平整的漆膜，但沉积量很小，漆膜很簿且涂覆不均，光泽度也不好。另外，温度低漆液黏度过大，电沉积过程中产生的气泡难以逸出，也容易造成涂层的针孔等缺陷，使腐蚀气体从针孔进入磁体内部产生腐蚀而降低磁体的抗腐蚀能力。漆液温度对涂层厚度的影响见图3。
复合钕铁硼/铁氧体黏结磁体电泳工艺研
究
© 1994-2009 China Academic Journal Electronic Publishing House. All rights reserved. wwwki
57
图3 电泳温度对电泳厚度的影响
对于EED 2060M 电泳漆，槽温选择在28～32℃范围内可获得均匀、光滑的涂层。
2.2.2 电压
黏结钕铁硼磁体具有一定的导电性，涂层厚度与磁体表面单位面积上通过的电量成正比，即:
H (t )=k ∫t
o u (t )J (t )d t
式中H (t )为涂层厚度,u (t )为施加的电压,J (t )为磁体表面的电流密度,k 为比例常数在电泳时通常采用恒电压供电，即u (t )=u 0为常值。由于树脂涂料本身绝缘，当工件表面沉积涂层后，电阻会快速升高直至电流密度J (t )为零，从而电泳结束。在电泳过程中，主要利用电压的大小来控制涂层厚度。一般极间电压高则电场作用力强，单位时间内会有更多的树脂离子沉积，因而涂层增厚。但电压过高会使涂层太厚且涂层粗糙，烘烤后外观质量差，出现桔皮堆积及针孔现象。当电压超过“破裂电压”时，沉积出的漆膜会被高电压击穿，电解反应加剧，电极表面产生大量的气体，从而使漆膜局部破损。故应
根据所涂工件的形状与大小、槽液温度高低，所需涂层的厚薄来选择最佳电压，特别是电泳漆刚配制时，其溶剂含量及导电率均相对较高，此时电泳电压应适当降低。本试验样品和EE D 2060M 电泳漆的合适电压为120～180V 。
2.2.3 固化温度
NdFe B 复合永磁体经电泳后必须经过烘烤固
化处理，使小分子树脂胶粒发生交联反应生成不溶
于水及有机溶剂的大分子树脂胶粒。固化温度过低，树脂未交联或交联不完全，涂层的附着力低，磁体的耐有机溶剂和抗腐蚀性能都很差；固化温度过高不仅易使涂层发黄还易使磁性能降低。试验表明，在150～170℃下固化得到的涂层外观光滑，力学物理性能和化学性能符合产品技术标准。
3 涂层性能
3.1 物理性能
黏结磁体中铁氧体磁粉含量质量分数小于
30%时，通过抛光、除油、阴极电泳获得的涂层表面
光滑、无缺陷，涂层厚度10～25μm ，铅笔硬度5H 。经过充磁过程的剧烈冲击，漆膜保持完好。3.2 耐蚀性能
电泳涂层盐雾试验按G B 10125—88进行，湿热试验在60℃，湿度95%下进行。表2给出了电泳涂层，无涂层的含2.5%环氧树脂的复合黏结磁体(锶铁氧体含量质量分数≤30%)的盐雾和湿热试验结果。
沈禾表2 环氧树脂对复合黏结磁体耐腐蚀性能的影响
涂层类型60℃下湿度为95%出现锈蚀时间/h
5%NaCl 盐雾试验出现锈蚀时间/h
无涂层185环氧树脂涂层
280
160
4 结 论
(1)复合钕铁硼/锶铁氧体黏结磁体中锶铁氧
体磁粉含量小于30%时，采用阴极电泳环氧树脂
涂层的磁体可获得具有优异耐腐蚀性能的涂层；而锶铁氧体磁粉在复合NdFe B 黏结磁体中超过30%时，却难以获得光滑的涂层。
(2)复合磁体基体的电阻率和表面状态直接影响磁体优质电泳涂层的形成。电阻率低且分布均匀、磁体表面光滑时，进行阴极电泳后较易生成光滑、均匀的优质涂层。
(3)采用上述方法制备的复合钕铁硼/
锶铁氧体黏结磁体，在漆液温度为28～32℃，电泳电压120～180V 下进行电泳并于150～170℃固化后,
所得涂层具有优异的抗腐蚀性能。
[参
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[编辑：詹小玲]
复合钕铁硼/铁氧体黏结磁体电泳工艺研究
© 1994-2009 China Academic Journal Electronic Publishing House. All rights reserved. wwwki
ing,Xi’an University of A rchitectural Science and Technol ogy, Xi’an710055,China)Cailiao B aohu2006,39(4),36～38 (Ch).Because of its high mechanical strength,str ong corr osi on
resistance,good conductivity and catalytic activity,Pt/Nb elec2 tr ode has been widely used in cathodi
c p r otecti on,industrial e2 lectr olysis,p reparati on of i on water,and s o on.Thus orthogonal test was carried out t o establish the op ti m al technol ogy f or the p reparati on of Pt/Nb electr ode fr om an aqueous electr op lating bath.The perf or mance of the resulting Pt/Nb electr ode was eval2 uated.A s the results,the op ti m ized electr op lating bath was de2 ter m ined t o be composed of15g/L Pt(NH2)2(NO2)2・2H2O, 100g/L NH2OS O2H,4g/L additive(organic a m ine).And the op ti m al electr op lating para meters were suggested as current den2 sity50～150A/m2and bath te mperature60～80℃.The p lat2 ing bath of the op ti m ized f or mulati on had good evenΟp lating ca2 pacity and could be used t o p repare compact and bright Pt/Nb e2 lectr ode of a thickness about10μm,at a cathode current effi2 ciency as much as32%.And the resulting Pt/Nb electr ode had good perf or mance.
Key words:Pt/Nb electr ode;ni obiu mΟbased electr op lating;p rep2 arati on
Effect of Technolog i ca l Param eters for L i qu i dΟPha se Pulse D ischarge of T i Electrode on the For ma ti on and Properti es of T i C Coa ti n g on Pl a i n Carbon Steel Substra te
J I E XiaoΟhua,J I N G A i,LU GuoΟhui,L I U YiΟfan,X I E Guang Οr ong(School ofMaterials and Energy Sources,Guangdong Poly2 technic University,Guangzhou510640,China)Cailiao B aohu 2006,
39(4),39～41(Ch).W ith a vie w t o the p r om inent eco2 nom ic significance in the surface modificati on of cutting t ools u2 sing liquidΟphase pulse discharge,Ti C cera m ic coating was p re2 pared on the surface of45steel,making use of the l owΟte mpera2 ture highΟenergy p las ma p r oduced bet w een Ti electr ode and45 steel i m mersed in liquid ker osene in the p resence of continual pulse discharge.The effect of the pulse discharging parameters on the for mati on and hardness of the Ti C coating was investiga2 ted.Results showed that the peak current and pulse onΟti m e had p ri m ary effects on the coating for mati on,while the pulse offΟti m e and depositing ti m e had al m ost no effect on the hardness but thickness of the Ti C coating.Itwas feasible t o obtain Ti C coating with high hardness at a relatively s mall peak current and short pulse durati on.
Key words:Ti electr ode;pulse discharging;Ti C coating;tech2 nol ogical para meters
Curren t St a te and Progress of Research on Copper I nh i b i2 tors
HE Jun,Y U Ping,LUO YunΟbai(School of Che m istry and Mo2 lecular Science,W uhan University,W uhan430072,China)Cail2 iao B aohu2006,39(4),42～47(Ch).The research p r ogress a2 bout copper and copper all oy inhibit ors was revie wed.Thus the synergistic effects a mong copper and its all oy inhibit ors and vari2 ous other inhibit orswere discussed with res pect t o acidic mediu m, Cl-Οcontai
ning mediu m,sea water,and nearly neutral aqueous mediu m.The current state and devel opment trend about the re2 search method and p retreat m ent of the inhibit ors were briefed as well.
Key words:inhibit or;copper all oy;copper corr osi on
Study on HotΟD i p A lu m i n i z i n g Technology for O il P i pe Steels and Properti es of the HotΟD i pped A lu m i n i z i n g Coa t2 i n g
J I A NG M ing,L I GuoΟxi,L I U ChangΟsheng,ZHNEG YiΟran (I nstitute ofMaterials,Northeast University,Shenyang110004, China)Cailiao B aohu2006,39(4),48～51(Ch).The oil p i pes made of J55and N80steels are liable t o corr osi onΟinduced perforati on,which leads t o seri ous obstacle and da mage t o the safe p r oducti on in oil fields.Fortunately,it is feasible t o greatly increase the heatΟand corr osi onΟresistance of the steels making use of hotΟdi p alu m inizing.Thus a study was made with res pect t o the op ti m izati on of hotΟdi p alu m inizing technol ogy for the oil p i pe steels,and the t w oΟbath flux method was established as the op ti m al alu m inizing technol ogy for the oil p i pe steels,based on comparis on with vari ous other methods for alu m inizing.The thickness and m icr ostructure of the resulting hotΟdi p alu m inizing coatings on J55and N80steelswere analyzed by means of op tical m icr oscopy.The corr osi on resistance of the J55and
N80steels, with and without the hotΟdi p alu m inizing coatings,i m mersed in aqueous s oluti on of3%NaClwas comparatively evaluated,while the fracture strength of the J55and N80steels with and without the hotΟdi p alu m inizing coatings was deter m ined using a pullΟf orce machine f or strength measurement.The results showed that the hotΟdi p alum inizing coatings on both the J55and N80steels were composed of alu m inu m layer and FeΟA l inter metallic com2 pound layer.The J55and N80steels coated with the hotΟdi p a2 lu m inizing coatings showed better corr osi on resistance than those without the alu m inizing coatings,but the mechanical strength of the alu m inized steels was decreased t o s ome extent.Na mely, owing t o the te mpering at high te mperature and gr owing up of carbides during the alu m inizing p r ocess,the fracture strength of the alu m inized J55and N80steels dr opped by10.5%and8. 2%,res pectively,as compared t o those without alu m inizing. Key words:hotΟdi p alu m inizing;J55and N80steels;heat-re2 sistance;corr osi on resistance
Prepara ti on and Appli ca ti on of a Novel W a ter-Soluble Corrosi on I nh i b itor Used i n O il F i eld
HUANG XueΟbin1,2,CHE N ZongΟlin1,2,ZHAO W enΟzhen1 (1.School of M aterials,Xi’an J iaot ong University,Xi’an 710049,China;2.No.1O il Extracti on Fact ory,Zhongyuan O il Field,Puyang457071,China)Cailiao B aohu2006,39(4),52～54(Ch).W ith a vie w t o the p r oblem s s
uch as large s olubility in oil and poor inhibiti on functi on of currently used corr osi on in2 hibit ors in oil fields,a novel waterΟs oluble corr osi on inhibit or ZYCΟ1was devel oped based on a series of op ti m izati on tests concerning emulsificati on behavi or,waterΟs olubility,and corr o2 si onΟinhibiting effect.The corr osi onΟinhibiti on acti on of the ne wly devel oped corr osi on inhibit or ZYCΟ1was investigated u2 sing sealed stirring method in an evenly m ixed waterΟoil fluid.It was found that ZYCΟ1intr oduced int o the wells and oil p i pes as the waterΟs oluble corr osi on inhibit or was capable of greatly de2 creasing the t otal a mount of Fe i ons and the corr osi on rate as well,which could make it feasible t o put ZYCΟ1int o br oader field app licati ons.
Key words:waterΟs oluble corr osi on inhibit or;corr osi on rete; corr osi on inhibiti on acti on;app licati on
Study of Electrophoresis Technology for NdΟFeΟB/SrΟFer2 r ite Bonded Co m posite M agnet
J I A NG L iΟqiang1,CHE N Q iaoΟling1,L I RunΟfeng2,Q IW anΟliang1(1.School of Che m ical Engineering and M aterials,Zhe2 jiang Polytechnic University,Hangzhou310014,China;2.Han2 gzhou J ingzheng Magnet I ndustry and Trade Cor porati on L td., Hangzhou311612,China)Cailiao B aohu2006,39(4),55～57 (Ch).The app licati on of bonded NdΟFeΟB magnet is partly hindered by its
poor corr osi on resistance at high te mperature and in hu m id envir on ment.Fortunately,it is feasible t o greatly in2 crease the corr osi on resistance of the NdΟFeΟB magnet using va2 ri ous coatings.Thus the effects of the composite per manent mag2 net substrate and of cathodic electr ophoresis p r ocessing para me2 ters on the coating quality were investigated,based on measure2 ment of the resistance using a directΟcurrent resistance bridge and of the corr osi on resistance using saltΟs p raying test and hu2 m id-hot i m mersi on test.A s the results,it was feasible t o p re2 pare a compact and s mooth coating with good corr osi on resistance on the NdΟFeΟB/SrΟferrite bonded composite magnet containing SrΟferrite bel ow30%,at op ti m ized electr ophoresis para meters of lacquer temperature28～32℃,voltage120～180V,and cu2 ring te mperature150～170℃.However,it beca me infeasible t o obtain an electr ophoresis coating of good corr osi on resistance on the composite NdΟFeΟB/SrΟferrite magnet when its SrΟferrite r ose above30%,owing t o the shar p increase in the resistance. Key words:cathodic elechr ophoresis;composite per manent mag2 net;NdΟFeΟB/SrΟferrite bonded composite magnet
D evelop m en t of An ti bacter i a l Pa i n t and Coa ti n g for Co ili n g M a ter i a ls
ZHANG W enΟtao1a,SH I L iΟyi1a,ZHONG Q ingΟdong2,Z
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