基于人工神经网络预测Ni-W合金镀层的硬度和耐腐蚀性能

Artificial Neural Network-based Prediction of Hardness and Corrosion Resistance of Ni-W Alloy Coating

目的预测Ni-W合金镀层的硬度和耐腐蚀性能,优化Ni-W合金镀层的电沉积工艺。方法在柠檬酸-硫酸盐溶液体系中直接沉积制备Ni-W合金镀层,并将实验所得镀层数据作为学习样品,利用BP神经网络对建立了Ni-W合金电沉积过程参数对镀层硬度和腐蚀电流密度之间的映射关系。结果低碳钢表面所沉积的Ni-W合金镀层表面均匀致密,与基体结合良好,能够有效地对基体起到保护作用。第二隐层的加入使得3-7-15-2四层网络达到网络收敛的训练次数（1 215 365次）远小于3-7-2三层网络的训练次数（239 950 000次）。四层网络预测所得镀层的硬度和腐蚀电流密度与实验值十分相近,其相对误差≤5.03%。结论 BP神经网络能够准确建立电沉积Ni-W合金镀层的工艺条件和目标性能之间的映射关系,在本文所用的沉积体系和参数范围内,Ni-W合金镀层的显微硬度在296~982HV之间,其硬度最大时所对应的电沉积工艺条件为：p H=7.2,电流密度8 A/dm2,WO42＋浓度为0.46 mol/L。Ni-W合金镀层的腐蚀电流密度在7.3~100μA/cm2范围内。镀层耐蚀性能最好时,即镀层腐蚀电流密度最小时的电沉积工艺条件为：p H=6.4,电流密度0.36 A/dm2,WO42＋浓度为0.34 mol/L。

The work aims to predicte hardness and corrosion resistance so as to optimize the deposition process of electrodeposited Ni-W alloy coating. Ni–W alloy coating was prepared by direct deposition in aqueous citrate-sulphate solution system. Coating statistics obtained by means of experiment shall be taken as samples to be studied. A neural network was used to establish electro-deposition process parameters of Ni-W alloy, so as to reflect mapping relation between coating hardness and corrosion current density. Ni-W alloy coating deposited on surface of low-carbon steel was uniform and compact, provided with good adhesion to the substrate. Hence it could protect the substrate effectively. With the addition of second hidden layer, 3-7-15-2 four-layer network reaches training times of net work convergence（1 215 365 times）, far less than that of 3-7-2 three-layer network（239 950 000 times）. The predicted values of hardness and corrosion current density（Jcorr） were close to the values got by experiment, and the relative error was≤ 5.03%. An accurate mapping relation between process conditions of electrodeposited Ni-W alloy coating and target properties can be built by BP neural network. The microhardness of Ni–W alloy coating was within 296~982HV. Electrodeposition process conditions corresponding to maximum hardness are as follows： p H value of 7.2, deposition current density of 8 A/dm2 and WO42＋ content of 0.46 mol/L. Corrosion current density of the Ni–W alloy coating is within 7.3~100 μA/cm2. Electrodeposition process conditions correponding to lowest corrosion current density, i.e., best corrosion resistance, are as follows： p H value of 6.4, deposition current density of 0.36 A/dm2 and WO42＋ content of 0.34 mol/L.