Microstructural and Hardness Evaluations of a Centrifuged Sn-22Pb Casting Alloy Compared with a Lead-Free SnAg Alloy
- PDF / 3,415,891 Bytes
- 13 Pages / 593.972 x 792 pts Page_size
- 45 Downloads / 211 Views
CTION
ALTHOUGH the traditional Sn-Pb alloys have been restricted or banned by the European RoHS Directive (Restriction of Certain Hazardous Substances) and U.S. Environmental Protection Agency regulations, it is known that for 30 years, these Sn-Pb alloys were widely used.[1–3] Various industrial applications, including electro-electronic fields, have been applied to these Sn-Pb–based alloys. The jewelry and semijewelry industries have also used Sn-Pb casting alloys due to their low cost and workability, and because of their solderability and good wetting performance facilitating gold plating. Although the tendency to replace Sn-Pb alloys with other having environmentally friendly aspects is evident, these alloys are still widely used in semijewelry industries with some recycling and discarding restrictions. In this respect, reinforcements designed to replace the traditional Sn-Pb alloys with green alloys have been provided by a group of medium size Brazilian gold plating jewelry companies and their association (i.e., Association of Gold-plated Jewelry from Limeira city, the Associac¸a˜o Limeirense de Joias–ALJ[4]). These green alloys can be LUZ MYRIAN SATIZABAL and DIEGO COSTA are with the School of Technology, University of Campinas–UNICAMP, Limeira, SP 13484-332, Brazil. GUILHERME OTTAMR HAINICK, DIEGO RODRIGO MOURA, AUSDINIR DANILO BORTOLOZO, and WISLEI RIUPER OSO´RIO are with the Research Group in Manufacturing of Advanced Materials, School of Applied Sciences/FCA, University of Campinas–UNICAMP, Limeira, SP 13484-350, Brazil. Contact email: [email protected] Manuscript submitted December 13, 2015. METALLURGICAL AND MATERIALS TRANSACTIONS A
constituted from a wide group of Pb-free Sn-based alloys (e.g., SnAg, SnBi, SnCu, SnZn, etc.). From a metallurgical point of view, it is well known that unsoundness, strength, hardness, ductility, workability, and corrosion/oxidation behavior are properties strongly associated with thermal, compositional, and operational parameters, which can be adequately used to regulate the microstructural array in semijewelry casting.[5–8] It is also well known that traditional Pb-containing solder alloys exhibits low cost when compared with all other Sn-based alloys.[9,10] This is due to Pb having low cost and plentiful availability,[9] which promises wide application in both microelectronic components and jewelry/semijewelry industries. Besides, the Sn-Pb-based alloys evidence better wettability and similar shear strength in joints on Cu substrates when compared to Sn-Ag-Cu, Sn-Ag, and Sn-Ag-Bi.[9–13] Although it seems that the Sn-Pb alloy’s replacement with Pb-free environmentally friendly solder is an irreversible tendency,[12] it should be remembered that Pb does not vaporize[9] and that its hazardous effect is minimized or eliminated during soldering when the appropriate process is used. Its hazardous effect on human health seems to be correlated with inadequate disposal waste.[9] Considering the Sn-Pb solders, there are two directions: (1) there is a trend to substitute w
Data Loading...
