Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
Zn-Ni alloy electroplating behaves as anodic coating but has better mechanical properties in comparison with pure Zn coatings. Hence, Zn-Ni coating is accepted as an environmentally friendly alternative to cadmium coatings which is very toxic during producing and use. | Vietnam Journal of Science and Technology 55 (5B) (2017) 187-193 INFLUENCE OF NICKEL CONCENTRATION ON THE CHARACTERISTICS OF THE ELECTROPLATING Zn-Ni ALLOY Bui Thi Thanh Huyen, Le Viet Dai, Ngo Thi Minh Thuy, Hoang Thi Bich Thuy* School of Chemical Engineering, Hanoi University of Science and Technology, 1 Dai Co Viet, Hai Ba Trung, Ha Noi * Email: thuy.hoangthibich1@hust.edu.vn Received: 11 August 2017; Accepted for publication: 7 October 2017 ABSTRACT Zn-Ni alloy electroplating behaves as anodic coating but has better mechanical properties in comparison with pure Zn coatings. Hence, Zn-Ni coating is accepted as an environmentally friendly alternative to cadmium coatings which is very toxic during producing and use. In this paper, Zn-Ni alloys were electrodeposited from sulfate electrolyte baths at various ratios of Ni2+/Zn2+. Influences of nickel concentration on the plating process were investigated. The composition, morphology and structural properties of the thin films were analyzed by scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) measurements. Electrochemical behaviour of the plated thin films was characterized by open circuit potential and potentiodynamic polarization curves. It was seen that the optimum condition for Zn-Ni electroplating was at temperature of 50 C, current density of 5 A/dm2, anode - cathode distance of 2.5 cm with stirring. Current efficiency of the plating process and characteristics of the Zn-Ni alloy coatings depended much on the nickel concentration in the plating bath. The best properties were found for the electroplated alloy coating with nickel content in the range of 12 - 14 %. Keywords: Zn-Ni coating, Zn-Ni alloy, electroplating, cadmium coating substitution. 1. INTRODUCTION Sacrificial metallic coatings, such as those based on Zn and Cd are used to protect steel components against corrosion. Zinc is used in automotive applications, but Cd coatings are at present used
