Fabrication And Characterization Of Lead Free Pewter Alloys
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Date
2011-08
Authors
Chou, Soklin
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Lead free pewter alloys with various composition Sn-(1-3%wt)Cu and Sn-(1-
3%wt)Al binary alloys and Sn-(1-3%wt)Cu-(5-7%wt)Sb ternary alloys were
prepared by mixing raw materials, melting, homogenizing, and casting in a mild steel
die. The alloy samples were characterized for phase identification via X-ray
diffraction (XRD) analysis, and thermal behaviour via differential scanning
calorimetry (DSC). Microstructures of the alloys were studied by using optical
microscope (OM), field emission scanning electron microscopy (FESEM) and
energy dispersive X-ray (EDX) analysis. The mechanical and physical properties of
lead free pewter alloys were characterized via density test, hardness test, tensile test,
castability test and surface appearance observation. A comparison was made by
using commercial pewter alloy (CPA). XRD, FESEM, and EDX analysis of the
alloys indicated the formation of intermetallic phase which may be responsible for
the required hardening of Sn-based alloys. The intermetallic compound of Cu6Sn5
found in Sn-Cu pewter alloys resulted in higher hardness. On the other hand,
formation of intermetallic compound of Cu6Sb5 and SbSn increase the hardness of
Sn-Cu-Sb pewter alloys. However, these intermetallic compounds were found to
deteriorate elongation of pewter alloys. DSC, FESEM, and EDX analysis of Sn-Al
pewter alloys showed the formation of eutectic structure of Al+βSn led to an increase
in hardness and strength of these alloys but deteriorates the ductility. A higher
amount of Sn in lead free pewter alloys tends to increase the fluidity length while the
addition of Cu and Sb in alloy increases its brightness. The lead free pewter alloy of
92Sn-3Cu-5Sb has higher hardness and strength than others. Hence, this alloy is
more suitable to produce large objects that require higher strength and hardness to
sustain loading during handling and use. Normally, small object requires high
castability to produce a complex shape. Thus, 99Sn-1Cu and 99Sn-1Al alloys are
more suitable to produce small objects since they have a higher castability than that
of other alloys.
Description
Keywords
Fabrication and characterization , of lead free pewter alloys