Corrosion Characteristics of Electrodeposited Ni Mo P Alloy Immersed in NaCl Solution

用失重法、阳极极化曲线、Ｘ光电子能谱（ＸＰＳ）以及俄歇电子能谱（ＡＥＳ）研究了电沉积ＮｉＭｏＰ合金镀层在５％ＮａＣｌ溶液中的腐蚀特性．非晶态ＮｉＭｏＰ合金镀层比晶态ＮｉＭｏＰ合金镀层有较低的腐蚀速度．阳极极化曲线表明，ＮｉＭｏＰ合金镀层中，镍的摩尔分数为０．７１９～０．８６８时，随镀层中磷含量的增加，腐蚀电位正移；而活化区的峰电流随镀层中钼含量的增加而增加．磷含量对活化区的峰电流以及钼含量对腐蚀电位的影响均很小．ＸＰＳ和ＡＥＳ分析指出，经５％ＮａＣｌ溶液中浸渍后，ＮｉＭｏＰ合金镀层表面形成厚度约为５０ｎｍ的氧化膜．这层氧化膜主要由Ｎｉ２Ｏ３，ＭｏＯ３和ＰＯ４３－等构成，其在电解质溶液和合金间起着阻挡层的作用．The corrosion characteristics of electrodeposited Ni Mo P alloy immersed in 5wt.% NaCl solution were investigated using immersion, anodic polarization curves, XPS and AES analysis. The corrosion rates of amorphous Ni Mo P alloys are lower than that of crystalline Ni Mo P alloys. Anodic polarization curve experiments show that for the electrodeposited Ni Mo P alloys, the nickel mol fraction of which has in between 0.719 and 0.868, the corrosion potential moves to positive with the increase of P content, and the peak current value of active region increase with the increase of Mo content in alloys, though the effects of P content on the peak current of active region and of Mo content on the corrosion potential are insignificant. XPS and AES analyses indicate that after immersion in 5wt.% NaCl solution, an oxidation film of about 50 nm in thickness is formed on the surface of Ni Mo P alloys. This oxidation film is composed of Ni 2O 3,MoO 3 and PO 3- 4, and acts as a barrier between the alloy and the electrolyte.作者联系地址：湖南师范大学化学系,天津大学应用化学系Author's Address: Department of Chemistry, Hunan Normal University, Changsha, Hunan, 410006 Yao Suwei Guo Hetong Department of Applied Chemistry, Tiangjin University, Tianjin, 30007

Surplus Function Quantum Monte Carlo Approach

为量子MOnTECArlO方法提出一条新途径──剩余函数法；引入了SCHrOdIngEr方程剩余函数的概念，利用剩余函数将一种新的有明显物理意义的试探函数应用到量子MOnTECArlO过程中；这种试探函数是通过一种迭进式的方式确定的，它不需要在MOnTECArlO过程中优化参数.文中我们将给出这种试探函数的具体形式，证明由这种试探函数求出的能量期望值收敛于体系真实的能量值；文中还给出这种试探函数能量期望值的计算公式以及它在变分MOnTECArlO过程中的具体运算步骤；几个分子的算例说明这种试探函数的能量期望值不仅逐步逼近体系真实的能量值，而且逼近速度也非常快，一般只需要4~5次迭进即可获得90%以上的相关能.据作者所知，这种试探函数的计算精度和收敛速度在目前量子MOnTECArlO方法中均是最高的.A concept of surplus function for Schrodinger equation is put forward.A novel quantum Monte Carlo approach entitled surplus function method is suggested with use of a novel trial function of significant physical meaning which is based on the proposed surplus function.The trial function is of an iteration-type and suffers no time-consuming parameter optimum in a quantum Monte Carlo process.It is theoretically proved that the energy expectation value obtained from the proposed trial function converges to the exact energy value of the system inveshgated.In addition,computation formulas and procedures for energy expectation value are presented.Calculations for several molecules indicate that the energy expectation value obtained from the trial function does converge to the exact energy value of the investigated system and the converging rate is very fast as generally only 4-5 iterations achieves over 90% correlation energy.To our knowledge, both the calculating precision and converging rate of the trial function proposed are the highest one in the quantum Monte Carlo approach at present time.国家自然科学基金;湖南省教委科研基

Kinetic model of induced codeposition of Ni-Mo alloys

The kinetic model of induced codeposition of nickel-molybdenum alloys from ammonium citrate solution was studied on rotating disk electrodes to predict the behavior of the electrode-position. The molybdate (MoO42-) could be firstly electrochemically reduced to MoO2, and subsequently undergoes a chemical reduction with atomic hydrogen previously adsorbed on the inducing metal nickel to form molybdenum in alloys. The kinetic equations were derived, and the kinetic parameters were obtained from a comparison of experimental results and the kinetic equations. The electrochemical rate constants for discharge of nickel, molybdenum and water could been expressed as k(1)(E) = 1. 23 x 10(-9) C(Ni)exp( - 0.198FE/RT) mol/(dm(2).s), k(2)(E) = 3.28 x 10(-10) C(Mo)exp(- 0.208FE/RT) mol/(dm(2).s) and k(3)(E) = 1.27 x 10(-6)exp(- 0.062FE/RT) mol/(dm(2).s), where C-Ni and C-Mo are the concentrations of the nickel ion and molybdate, respectively, and E is the applied potential vs. saturated calomel electrode (SCE). The codeposition process could be well simulated by this model