The Electroless Plating Ni-Fe-P Alloy and Its Voltammetric Behavior

在以次亚磷酸钠为还原剂 ,硼酸为缓冲剂和柠檬酸钠为络合剂的碱性介质中 ,研究了镍_铁_磷合金化学沉积条件 (pH值 ,温度及 [Fe2 + ]/([Ni2 + ]+[Fe2 + ])物质的量比 )对沉积速率和镀层组成的影响 ;并由此建立镀液稳定的最佳沉积工艺 .实验表明 ,镀液中硫酸亚铁对沉积镍_铁_磷合金有阻碍作用 (降低了化学沉积速率 ) ,造成镀层中铁含量不高 (小于 2 0 % ) ,使用循环伏安技术研究了镍_铁_磷合金的电沉积机理 .结果发现铁对次亚磷酸钠的氧化不起催化作用 ,提高镀液温度和pH值有增加沉积速率之效Electroless Ni_Fe_P alloy deposition from an alkaline bath, containing sodium hypophosphite as reducer, boric acid as buffer agent and sodium citrate as complexing agent, was investigated. To increase the plating rate and to inprove the bath stability, the deposition parameters were optimized. The effects of process parameters (pH,temperature and mole ratio of [Fe 2+ ]/([Ni 2+ ]+[Fe 2+ ]) on the plating rate and deposit composition were examined and it was found that the presence of ferrous sulfate in the bath has an inhibitory effect on the alloy deposition. As a consequence, the per_centage of iron in the electroless Ni_Fe_P alloys never reaches high values which is lower 20.0%. Using cyclic voltammetry the electrodeposition mechanism of Ni_Fe_P alloys was investigated. It was observed that the presence of ferrous sulfate in the bath decreases the deposition rate and the iron doesn′t catalyst on the oxidation of hypophosphite. However, the increase in temperature or pH leads to improving the deposition rate.作者联系地址：华侨大学材料科学与工程学院,厦门大学化学系,固体表面物理化学国家重点实验室 福建泉州362011 ,福建厦门361005Author's Address: 1.College of materials science and engineering,Huaqiao university,Quanzhou 362011, China, 2.State key laboratory for physical chemistry of solid surface,Department of chernistry, Xiamen university, Xiamen 361005, Chin

正交匹配追踪和BIC准则的自适应双频段预失真模型优化算法

针对双频段预失真模型复杂度高以及当前的模型优化算法不具有自适应性的问题,提出一种自适应的模型优化算法.采用双频段广义记忆多项式作为预失真模型,通过正交匹配追踪算法对原始模型的基函数项进行排序,每次迭代时用所有已挑选的基函数项构成备选模型,推导了模型输出向量元素服从非独立同分布情况下的贝叶斯信息准则(Bayesian Information Criterion,BIC),并将BIC值最小的备选模型作为优化后模型,从而在原始模型稀疏度和拟合误差门限未知情况下,实现了模型的自适应优化.结果表明:优化后模型与原始模型相比,二者分别预失真后的信号在邻道功率比和归一化均方误差方面均非常接近,预失真效果良好,而模型的系数量减少了75%以上.国家自然科学基金项目(No.61401099);;福建省教育厅项目(No.JAT170087

Effect of Process Conditions on Electroless Ni-Co-P alloy

采用硼酸为缓冲剂 ,柠檬酸钠为络合剂化学镀Ni Co P合金。考察了镀液pH值、钴离子浓度和温度对化学镀Ni Co P沉积速度的影响 ;研究了钴离子浓度对镀层组成的影响 ,获得了化学镀Ni Co P合金的最佳工艺条件为 :镀液pH值为 7.0 ,操作温度 90℃ ,CoSO4 ·7H2 O浓度为 11g/L。此工艺下镀液稳定性好 ,镀层沉积速度快 ;所得镀层为非晶结构。The electroless Ni\|Co\|P alloys were deposited from bath using H\-3BO\-3 as buffer agent and sodium citrate as complexing agent. The effects of pH, concentration of Co\+\{2+\} and temperature on depositing rate were studied including the effect of concentration of Co\+\{2+\} on the composition of deposit. Formula of electroless Ni\|Co\|P alloys plating was optimized so as to obtain high depositing rate and good stable bath that pH was 7.0, temperature was 90 ℃ and CoSO\-4·7H\-2O content was 11 g/L. The Ni\|Co\|P plating was an amorphous structure.国家自然科学基金资助课题 (批准号 :2 0 0 730 35

Investigation of Mixed Potential in Electroless Ni-W-P Plating

　测量了化学镀Ni P和Ni W P过程混合电位随时间的变化,并分析其变化规律。指出Emix的正移与pH值随时间而降低有关,而且pH值的降低会加速化学镀的诱发过程。低碳钢诱发化学镀Ni W P会在混合电位 时间曲线上出现两个电位阶梯,其原因在于低碳钢在给定的镀液体系中稳定电位不够负,不能提供足够的能量使化学镀Ni W P快速发生,只有当表面形成达到一定覆盖度的具有催化活性的Ni原子层后,才能迅速地诱发化学镀过程;而Ni P和Ni W P的稳定电位足够负,可以使化学镀过程快速诱发,故仅有一个电位阶梯。The mixed potentials as a function of time were measured during the process of electroless Ni\|P and Ni\|W\|P plating, and their patterns were also analyzed. It was indicated that the positive shift of Emix was related to the pH value which decreased with time, and that the decrease in pH could accelerate the initiation of electroless plating. Two potential steps were observed on Emix\|t curves when the mild steel was used as the substrate of electroless Ni\|W\|P plating because of its less negative stable potential, which couldn't supply enough energy for rapid electroless deposition of Ni\|W\|P, and none but a layer of catalytic nickel with considerable coverage on mild steel was needed for rapidly initiating the electroless plating. However, since sufficient negative stable potentials, Ni\|P and Ni\|W\|P were able to initiate electroless deposition rapidly, hence only one potential step was found.国家自然科学基金资助项目(20073035

Electroless Nickel Plating on Glass Substrate by Palladium-Free Activation

A new process of electroless plating of nickel on glass substrate without using conventional palladium choride solution activator has been developed. The activation solution consists of nickel acetate, citric acid, and methanol. Heat treatment process of activation solution has been monitored by DTA TGA and XRD. The results show that the activation solution was completely decomposed into hexagonal Ni and cubic NiO at 310 ℃. The amorphous electroless deposits was determined by XRD and it contains Ni 88 4% and P 11 6%(mass fraction) by chemical analysis.国家自然科学基金资助课题 ( 2 0 0 73 0 3 5

PREPARATION AND CORROSION PROPERTIES OF ELECTROLESS Ni-Zn-P ALLOY DEPOSITS

采用柠檬酸钠为络合剂 ,在氨性缓冲介质中化学镀Ni Zn P合金 .考察了工艺参数 (pH、ZnSO4·7H2 O浓度和温度 )对沉积速度和镀层组成的影响 .发现Zn离子在沉积过程中起阻碍作用 ,致使镀层中Zn含量不高 (最多含16 .0mass% ) .采用差示扫描量热 (DSC)和X射线衍射 (XRD)技术研究所得化学镀Ni Zn P合金 (Ni=78.7mass % ,Zn =11.7mass % )的晶化行为和结构 .结果表明 ,镀态Ni Zn P合金主要由非晶相和少量立方镍两相构成 .热处理至 384 .8℃时出现四方Ni3 P相 ,至 5 80 .7℃时出现Ni5Zn2 1相 .镀态及热处理后的Ni Zn P合金 (Ni=78.7mass% ,Zn =11.7mass% .)在 3.5 %NaCl中 (pH =7.0 )的腐蚀失重及阳极极化测量 .结果表明 ,该合金的耐腐蚀性能优良 ,特别是镀态Ni Zn P合金 .Electroless Ni-Zn-P alloy deposits from an alkaline bath containing NH 4Cl as a buffer agent and sodium citrate as a complexing agent was investigated.The effects of deposition parameters(pH,concentration of ZnSO 4 ·7H 2O and temperature) on the plating rate and the deposit composition was examined respectively.It was found that the presence of zinc in the bath has an inhibitory effect on the alloy deposition.As a consequence,the percentage of zinc in the electroless Ni-Zn-P alloys never reaches high values.The structure and the crystallization behavior of the deposit has been characterized by XRD and DSC.The results show that the as-plated deposits consist of mainly an amorphous structure together with some cubic phase Ni.The deposits crystallized into Ni 3P at 384.8℃ and transformed into Ni 5Zn 21 at 580.7℃.The weight loss test and the anodic polarization measurements of the as-plated and the heat-treated deposits in 3.5mass% NaCl solution (pH7.0) indicate that the two deposits show good corrosion resistance,especially the as-plated deposit.国家自然科学基金资助课题 ( 2 0 0 73 0 3 5

Studies on Preparation Conditions and Crystallization Behavior of Electroless Plating Ni-Fe-P Alloy Deposits

采用硼酸为缓冲剂,柠檬酸钠为络合剂在碱性介质中化学沉积Ni Fe P合金.考察了工艺条件如pH、FeSO4·7H2O浓度和温度对沉积速度的影响.获得了沉积速度快,镀液稳定性好的工艺条件.采用差示扫描量热和X射线衍射研究了Ni Fe P合金的晶化行为.结果表明,镀层在镀态呈非晶结构,镀层在200.5℃晶化为亚稳的Ni Fe合金,310℃晶化为立方FeNi3合金,369.2℃晶化为四方的Ni3P,而491.3℃为继续生成FeNi3的吸热峰.The electroless plating NiFeP alloy deposits were prepared in alkaline bath using H3BO3 as a buffer agent and sodium citrate as a complexing agent.The effects of pH ,concentration of ferrous sulfate and temperature on deposition rate were studied.The formula of NiFeP alloy electroless plating was optimized so as to obtain high deposition rate and good stability of the bath.The crystallization behavior of the deposits has been characterized by DSC and XRD.The results show that the asplated deposits have an amorphous structure.With heat treatment,the deposits crystallize into metastable NiFe alloy at 200.5 ℃,cubic FeNi3 at 310 ℃, square Ni3P at 369.2 ℃ and continuously into cubic FeNi3 at 491.3 ℃,respectively.国家自然科学基金(20073035)资

Effect of Thiourea on Nickel Deposition

通讯联系人, Tel: ( 86_592) 2181436, E_mail: hhwu@ xmu. edu. cn[中文文摘]应用循环伏安和阻抗＿电位法研究了硫脲(TU)对玻碳电极和镀镍玻碳电极上镍沉积过程的影响.结果表明,在玻碳电极上镍的电沉积呈现明显的电化学成核机理,而在镀镍玻碳电极上则无此特征.TU的存在虽阻碍了Ni晶核的形成,但却能加速晶粒的生长.[英文文摘]Effect of thiourea on nickel deposition at glassy carbon and nickel_deposited glass carbon elect rodes w as invest igated w ith cyclic voltammograms and impetance_potent ial curves. It was found that the nucleat ion processes occurred at the glassy carbon elect rode. However, this characteristics disappeared at the nicked_deposited glassy carbon elect rode. It w as suggested that the presence of thiourea hindered the nucleation processes, yet accelerated g rain growth. Curves of impetance_potent ial could sensitively detect effect of thiourea on nickel depositon and reflect changes in rate_determining step w ith potential.国家自然科学基金(20073035)资

Effect of Additives on Electroless Deposition Rate

基于化学镀Ni-W-P和Ni-P体系中,添加剂LaCl3、乳酸、Fe2(SO4)3、硫脲和2,2'-联吡啶的浓度对沉积速率的影响表现出较为一致的变化规律,即随添加剂浓度的增加,出现最大沉积速率的实验事实,建立了一种吸附模型并导出添加剂加速化学沉积的公式.根据该公式和实验结果进行曲线拟合,得到相当吻合的结果.由拟合结果可得到一些参数值,如吸附平衡常数等.添加剂在基体上的吸附平衡常数(K1)大于已吸附了还原剂的表面上的吸附平衡常数(K2).K1值大表明添加剂在基体表面吸附能力更强.LaCl3、硫脲和2,2'-联吡啶的K1、K2值远大于乳酸、Fe2(SO4)3的K1、K2值,这表明LaCl3、硫脲和2,2'-联吡啶的吸附能力远强于乳酸、Fe2(SO4)3的,因此,LaCl3、硫脲和2,2'-联吡啶所引起的沉积速率峰值的浓度远小于乳酸、Fe2(SO4)3的.It has been known experimentally that, additives, such as LaCl3, lac tic acid, Fe2(SO4)3, thiourea and 2,2′-bipyridine, regularly influence the e lectroless deposition rate, that is, there is a maximum deposition rate with inc reasing additives concentration. In order to explore this regularity, an adsorpt ion model is proposed and a deposition rate formula is deduced. The deposition r ate formula is used to operate nonlinear curve fitting. The fitting curves obtai ned, correspond with the experimental results. Some parameters can be obtained f rom the fitting results, such as adsorption equilibrium constants of additives. It is found that the adsorption equilibrium constant on the naked surface(K1) is larger than that on the adsorbed reductant(K2). The larger K1 means that additi ves adsorb on the naked surface more easily than on the adsorbed reductant. The adsorption ability of different additives also can be illustrated through K1 and K2. For example, the K1, K2 of LaCl3, thiourea and 2,2′-bipyridine are grea ter than that of lactic acid and Fe2(SO4)3. The comparison indicates that the ad sorption ability of LaCl3, thiourea and 2,2′-bipyridine is stronger than tha t of lactic acid and Fe2(SO4)3. Thus the concentration of LaCl3, thiourea and 2, 2′-bipyridine, which corresponds to maximum deposition rate, is smaller than that of lactic acid and Fe2(SO4)3.国家自然科学基金(20073035)~

Effects of LaCl_3 and Fe_2(SO_4)_3 on Electroless Ni-W-P Plating

研究了添加剂LaCl3 和Fe2 (SO4) 3 对化学镀Ni W P沉积速度、镀层组成结构和表面形貌的影响。结果表明 ,三氯化镧质量浓度为 1～ 1 0mg/L时化学镀Ni W P沉积速度提高 ,而大于 1 0mg/L时沉积速度随浓度增加而降低 ,使Ni W P镀层中的W含量降低 ,镀层颗粒尺寸减小。而硫酸铁提高沉积速度、降低镀层中的P含量 ,但对镀层结构和颗粒尺寸影响不大。能量分散谱 (EDS)分析镀层成分的结果表明 ,稀土镧是非消耗性的添加剂 ,而硫酸铁是消耗性的添加剂 ,后者由于在基体表面共沉积 ,形成化学镀的催化活性中心 ,从而促进了化学镀过程。The influences of additives LaCl 3 and Fe 2(SO 4) 3 in plating solution for electroless Ni-W-P deposition have been investigated as function of deposition rate, composition, structure and morphology of alloy formed. The results show that 1～10 mg/L LaCl 3 could accelerate deposition rate, whereas 20～100 mg/L LaCl 3 decrease deposition rate, reduce W content and diminish the grain size. Being different from LaCl 3, Fe 2(SO 4) 3 could increase deposition rate , reduce P content, and hardly affect the grain size. Energy Diffusion Specta (EDS) indicate LaCl 3 is not a consumptive additive, but Fe 2(SO 4) 3 is. Fe 2(SO 4) 3 raises deposition rate by forming catalytic centres, being deposited on the substrate surface.国家自然科学基金资助项目 ( 2 0 0 73 0 3 5