摘要
利用循环伏安法和红外漫反射光谱法研究化学镀镍过程中丙酸的作用机理.不同丙酸浓度下的循环伏安曲线表明,丙酸能同时促进Ni2+的还原和H2PO-2的氧化.根据丙酸分别与NaH2PO2和NiSO4共存时镍基体上吸附物的红外漫反射光谱变化,推断丙酸是通过与NaH2PO2和Ni2+形成表面络合物来促进化学沉积的.丙酸能与NaH2PO2形成分子间氢键,促使P—H键断裂并生成·PHO-2中间物,从而提高H2PO-2的氧化速度;同时,丙酸以其—OCO—官能团与Ni2+生成桥式配合物,有利于加速Ni2+的沉积.H2PO-2氧化速度的提高有助于磷的沉积,从而增大了化学镀层中的磷含量.
Propionic acid as an additive in electroless nickel plating will accelerate chemical deposition and raise P contents in the deposits. In this work, the action mechanism of propionic acid in the electroless plating were studied by cyclic voltammetry and infrared reflection spectroscopy. The vohammetric curves at various concentrations of propionic acid indicate that propionic acid will promote both cathodic Ni^2＋ reduction and anodic NaHEPO2 oxidation. According to the differences between the infrared reflection spectra of adsorbed propionic acid on Ni substrates and that of the adsorbed species when propionic acid co-exists with NaH2PO2 or NiSO4, it was proposed that the acceleration of chemical deposition was attributed to the formation of surface complexes of propionic acid with NaH2PO2 and NiSO4, respectively. Propionic acid could form intermolecular hydrogen bonds with NaH2 PO2, which promotes splitting of P--H bond in the reductant and producing PHO2^- intermediates, hence facilitates the oxidation of NaH2 PO2. At the same time, propionic acid is coordinated with Ni^2＋ via its --OCO-- group to form bridge complexes so as to promote NiSO4 reduction. The accelerating oxidation of NaHEPO2 in turn helps the deposition of P, as a result, P contents in the deposits increase with accelerating NaHEPO2 oxidation.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2006年第3期519-522,共4页
Chemical Journal of Chinese Universities
基金
国家自然科学基金(批准号:20073035)资助.
关键词
丙酸
有机添加剂
化学镀镍
沉积速度
Propionic acid
Organic additive
Electroless nickel plating
Deposition rate
