Ni-Sn alloy

In addition to the alloys in Table 4.21, Ni-Sn and Ni-Ti alloys also possess useful corrosion resistance. Ni-Sn alloys are extremely brittle and, because of this, are used only as electrodeposited coatings. Ni-Ti alloys over a wide range of compositions have been studied, of which perhaps the intermetallic compound NiTi (55 06Ni-44-94Ti) has attracted the most interest. 

Ni + Sn alloys have been studied by Lazarova and Nikolov.828 Ni + Fe alloys have been investigated by Lazarova and Raichev. pH and composition effects have been reported in both cases. 

A metal hydride battery similar to the nickel-cadmium battery has been developed by Sharp corporation. The battery is shaped in the form of a button of 20 mm diameter and can give 1.2 V. The anode in the battery is made of La-Ni-Sn alloy hydride, and the cathode is nickel oxide. Potassium hydroxide solution in polyamide-resin is the electrolyte. The battery exhibits high energy density (i.e.) 1.5 to 2.0 times that of the Ni-Cd battery, good cycling life and superior low temperature behaviours. 

H. Yamashita, T. Yamamura and K. Yoshimoto, The relation between catalytic ability for hydrogen evolution reaction and characteristics of nickel-tin alloys, J. Electrochem. Soc., 1993,140, 2242-2243 K. Yoshimoto, H. Yamashita and M. Miyashita, Development of Ni-Sn alloy plating active catholyte and application in industrial electro-dialyzer, Soda Enso (Soda Chlorine), 1994, 45, 418-427 Yoshida and T. Morimoto, A new low hydrogen overvoltage cathode for chlor-alkali cell, Electrochim. Acta, 1994, 39, 1733-1737. 

Fig. 14. Energy dependence of the polar Kerr rotation

Fig. 7.4 (a) Polarization curve for electrodeposition of the Ni-Sn alloy onto Ni electrode, (b) Typical cross section of coatings obtained at different current densities marked in (a) with solid squares ( ) (Reprinted from Ref. [5] with kind permission from Springer)... 

During the initial period of Ni%Sn alloy electrodeposition, similar behavior could be detected with less and more dense parts of the electrodeposit, as shown in Fig. 7.6. In the case of alloy electrodeposition, the shape of crystals is different. BaU-Uke crystals with the average composition 54 at.% Ni-46 at.% Sn (the composition was obtained by the EDS analysis) could be detected at the less dense part of the electrodeposit (a), while the more dense part of the electrodeposit of the average composition 47 at.% Ni-53 at.% Sn is characterized with distorted balls (b). After prolonged electrodeposition in the range of activation-controlled electrodeposition (i < 10 mA cm, Fig. 7.4a), compact electrodeposit is obtained [6], as shown in Fig. 7.4b. 

At higher cathodic current densities (potentials more negative than —1.2 V versus SCE, Fig. 7.4a), sudden increase of current density indicates simultaneous evolution of hydrogen. In such a case, the morphology of electrodeposited Ni-Sn alloy coatings [12] changes from the flat into nodular one, with the appearance of large, micron-sized pores, as shown in Fig. 7.7 for the Ni—Sn electrodeposit obtained at the current density of 75 mA cm . ... 

Lacnjevac U, Jovic BM, Jovic VD (2012) Electrodeposition of Ni, Sn and Ni-Sn alloy coatings from pyrophosphate-glycine bath. J Electrochem Soc 159 D310-D318... 

Tokuyama Soda Company developed NiS and Ni-Sn alloy coated cathodes [194-197]. The hydrogen overvoltage of the electroplated Ni-Sn alloy cathode, with a nickel content of 40-80wt%, in a mixed solution of NaOH and NaCl at 90°C, was about 100 mV. The Ni-Sn cathodes were used in retrofit-type membrane cells and filter press-type electrolyzers, both operating at 4kAm and 80°C. The cell voltages were constant for over 8 years. 

Ni-Sn alloy morphology was also foimd to be dependent on the ionic liquid composition and on operating parameters, but the chemical composition was found to be quite constant, regardless the value of the applied current density ( Florea et al., 2010). 

The formation of intermetallic compounds in solder joints during both reflow and subsequent annealing below the solidus temperature is also discussed. The classic Pb-Sn/metallization systems serve as a reference point [4—13]. In this context, the case of thermal cycling of solder joints of Cu/Ni/Au/Pb-Sn and the formation of Au-Ni-Sn intermetallic compounds at metallization interfaces is considered in detail [5,41-62]. The fast diffusion of Au controls the formation of Au-Ni-Sn alloys in this system [54—56]. In fact, some fundamental observations of the diffusion characteristics in Sn provide useful generalizations for all Sn-based solder systems, including Pb-free solders. Many Pb-free solders have near-eutectic compositions of Sn and various elements, often in ternary compositions. Those elements are often in relatively low concentrations, so the reactions between pure Sn and various metallizations are discussed as a basis for comparison. The formation of intermetalhc compounds at Pb-free solder/metaUization interfaces is discussed, and an attempt is made to understand the basic mechanisms of the growth processes and their relation to the reliability of interconnections. 

Chen, S. Yen, Y. Interfacial reactions in Ag-Sn/Cu Couples. J. Electron. Mater. 1999, 28, 1203. Zribi, Anis Borgesen, Peter Zavalij, Lubov Cotts, Eric J. Growth of Cu-Ni-Sn alloys in Pb free CuSnAg solder/Au-Ni. Metallization Reactions Symposium Y, Proceedings of the Fall Meeting of the Materials Research Society, 1999 Y8.10652. 

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