脉冲电镀Ni-Nd-P稀土合金薄膜的研究

【作者】 彭军；

【导师】 王玲玲；

【作者基本信息】 湖南大学 ， 材料物理与化学， 2005， 硕士

【摘要】 稀土薄膜已广泛地应用在磁学、光学、电催化和超导器件等领域。这类稀土薄膜功能材料已引起了材料工作者的广泛关注。 本文首先综述了稀土的性质和应用，阐述了采用脉冲电流在水溶液中电沉积稀土合金的理论原理，并分析了其相对于直流电镀的优势。 其次，本文对采用脉冲电流在水溶液中电沉积Ni-Nd-P稀土合金薄膜进行了研究。成功地在Cu基体上电沉积出厚度达5μm以上的灰白色的稀土合金薄膜。研究了脉冲电流、脉冲频率和脉冲占空比等电参数对镀层沉积速率、形貌、力学及耐腐蚀性能的影响，得出了能实现Ni-Nd-P三种元素共沉积且镀层质量好的脉冲电参数。利用扫描电镜进行了表面形貌分析，发现采用脉冲电流得到的镀态样品质量明显好于直流，表面更平整光滑，结晶更致密。在此基础上还研究了热处理温度对合金镀层显微硬度的影响，通过测试镀层的显微硬度发现：稀土合金镀层的硬度比基体铜的硬度大，脉冲镀层比直流镀层的硬度大；在300℃到600℃热处理后，随着退火温度的升高，镀层硬度值降低。 针对水溶液电沉积稀土合金的困难，本文还采用电化学方法研究镀液组成中的混合配体柠檬酸和氯化铵对稀土元素和镍还原电位的影响。研究发现：混合配体使稀土元素的还原电位正移，使稀土元素电沉积成为可能；使镍的还原电位负移，从而实现这两种还原电位相差较大的金属的共沉积。更多还原

【Abstract】 Thin films of rare earths have been applied widely in magnetic, optical, electrolytic and superconductor devices, and aroused many material researchers’ interests.In this paper, the properties and application of rare earth are summarized. Theory for pulse electrodeposition of rare earth metals and their alloys from aqueous solution are discussed, which has more advantages than using direct current.The gray films with a thickness up to 5μm of Ni-Nd-P alloys was successfully prepared on copper substrate by pulse electrodeposition from aqueous bath. The effects of pulse current, pulse frequency and duty ratio on deposition rate, morphologies, mechanical properties and corrosion resistance are studied.Proper technological parameters were obtained for the realization of the codeposition of Ni-Nd-P alloys with fine quality. The appearance of alloy films was analyzed by scanning electron microscopy(SEM).The result shows that the surface of alloy films is smoother and crystals are closer than using direct current. In addition, the effects of heat treatment temperature on the microhardness of alloy deposits were studied in this paper. The results of the microhardness of films show that the rare earth alloy films have higher hardness than Cu substrate material.The films deposited by pulse current are better than those by direct current in hardness. After heart treating from 300℃ to 600℃, hardness of rare earth alloy films decreases with the increase of annealing temperature.Aiming at the difficulties of electrodepositing rare earth alloys from aqueous solution, the effect of the complex formation (formed with Cit and NH4CI) on the reductive potential of RE and nickle was studied by the way of electrochemistry. The potencial of RE shifted positively which made itself electrodeposited from aquous solution possibly and nickle negatively which may make it into realities codepositing the two metals whose reductive potentials has far distance.更多还原