Soft Soldering of Ferritic Nodular Cast Iron to Aluminum-Zinc Alloy

	Soft Soldering of Ferritic Nodular Cast Iron to Aluminum-Zinc Alloy
Iraqi journal of mechanical and material engineering
Article 1, Volume 9, Issue 1, 2009, Pages 101-118
Abstract
The research devoted the possibility of soft soldering ferritic nodular cast iron to aluminum - zinc alloy, by using filler metals ASTM 60A, 40A & 70A. Cast iron was electroplated with iron and tin, while aluminum was coated with different layers of zinc, zinc-copper, zinc-copper-tin, zinc-copper-nickel and zinc-copper-nickel-tin. The specimens were fixed in the overlap position, and heated in a furnace to temperatures suitable to the soldering alloy in different holding times 5, 10, 15, 20, 25, 30 & 40min. The bond on the aluminum side could not be achieved when it was immersion coating with zinc while electroplating aluminum with copper over the zinc gave shear strength of 7MPa at 30min. holding time, using 60A as soldering alloy. Electroplating another layer of tin on aluminum increased shear strength to 11MPa at the same holding time and soldering alloy. While electroplating with nickel layer on the aluminum after zinc and copper layers gave shear strength of 10MPa. Adding fourth layer of tin on aluminum helped increasing shear strength to 23MPa . Using 40A as a solder alloy with the same two plated layers on cast iron and the four layers on aluminum gave shear strength of 14MPa while 70A solder achieved 13MPa at holding time 25min. The microstructure examinations show the formation of intermetallic compounds on both metals while the X-ray diffraction test shows the formation of FeSn and FeSn2 phases on the cast iron, and ε-Cu3Sn, η-Cu6Sn5 and γ-NiSn, δ-Ni3Sn4 on the aluminum, which are responsible for the bond.
Keywords
Solderability; Intermetallic Compound; Double Shear Test

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