2009 International Nuclear Atlantic Conference - INAC 2009 Rio de Janeiro,RJ, Brazil, September27 to October 2, 2009 ASSOCIAÇÃO BRASILEIRA DE ENERGIA NUCLEAR - ABEN ISBN: 978-85-99141-03-8

ZAMAK SAMPLES ANALYSES USING EDXRF

J. T. de Assis¹, H. Alves³, I. Lima¹, V. Monin¹, M. dos Anjos²,³, R. T. Lopes²

(1) Departamento de Engenharia Mecânica e Energia, Instituto Politécnico, UERJ Rua Alberto Rangel, s/n, Nova Friburgo, RJ, Brazil {[email protected]} {[email protected]} {[email protected]}

(2) Laboratório de Instrumentação Nuclear, PEN. COPPE/UFRJ Cidade Universitária, Rio de Janeiro, RJ, Brazil {[email protected]}

(3) Departamento de Física Aplicada e Termodinâmica, IF/UERJ Rua São Francisco Xavier, 524, sala B3020, Rio de Janeiro, RJ, Brazil {[email protected]} {[email protected]}

ABSTRACT

Zamak is a family of alloys with a base of and alloying elements of , magnesium and copper. Among all non-ferrous metal alloys, Zamak is one that has more applications, for their physical, mechanical properties and easy ability to electrodeposition. It has good resistance to corrosion, traction, shock and wear. Its low melting point (approximately 400 ° C) allows greater durability of the mold, allowing greater production of melted series parts. Zamak can be used in several kinds of areas, such as, to produce residential and industrial locks, construction and carpentry components, refrigerators hinges and so on. It’s observed that in some cases the quality of these products is not very good. The problem should be the quality of Zamak purchased by the industries. One possible technique that can be used to investigate the quality of these alloys is Energy Dispersive X-ray fluorescence. In this paper we present results of eight samples of Zamak alloy by this technique and it was possible to classify Zamak alloy and verify some irregularity on these alloys.

1. INTRODUCTION

Zamak alloys are part of the zinc aluminum alloy family. They are distinguished from the other alloys because of their constant 4% aluminum composition. The name Zamak is an acronym of the German names for the of which the alloys are composed by zinc, aluminum, magnesium and copper [1-3]. The common uses for Zamak alloys include: • Blenders • Mirror frames • Plumbing fittings • Zippers • Bathroom fixtures (faucets and shower heads) • Rickenbacker guitar "R" tailpieces • Staplers • Handles • Locks • Die-cast toys • Automotive parts • Ceiling fans • Golf clubs • Fishing reels • Wheel balancing weights (especially prominent in the European Union)

The most common Zamak alloy is Zamak-3, but Zamak-2, Zamak-5 and Zamak-7. These alloys are most commonly in die cast, which is the process of forcing molten metal under high pressure into mold cavities (which are machined into dies) and in the spin casting industry (a method of utilizing centrifugal force to produce castings from a rubber mold) [4,5].

A large problem with early zinc materials was zinc pest, a destructive, intercrystalline corrosion process of zinc alloys containing lead impurities. While impurities of the alloy seem to be the cause of the problem, environmental conditions such as high humidity (greater than 65%) may accelerate the process. Also, significant temperature changes can be damaging. It’s avoided by the use of 99.99% pure zinc metal [6-8].

The Energy Dispersive X-ray Fluorescence (EDXRF) is an analytical technique where the results allowed comparison between them and their classifications being are detected through electronic pulses and their amplitude is proportional to the X-ray energy. It’s a non destructive technique with quick answers and easy arrangements [9].

In this work, the EDXRF technique was used to analysis foreight certified Zamak samples. Those alloys have many commercial applications and assuch it’s expected that those samples have an excellent quality control, otherwise it could end in surface irregularities into the objects, leading to its destruction and any normal material that’s attached to them.

2. EXPERIMENTAL

It was used a mini X-ray tube with W anode. The system operates at a maximum high voltage of 40 kV and current of 200 μA. The spectrometer, X123, which already has inside it a silicon detector, a beryllium window, a pre-amplifier, a digital pulse processor and a multichannel are also part of the experimental apparatus. The X-ray tube is at 45° degree with the spectrometer (figure 1). The software used to capture the spectrum was the Amptek ADMCA (Fig. 2), which can control gain, number of channel and preset time. Each spectrum of the Zamak sample was measured with 15 kV and 100 µA, a 2 mm collimator and 1 minute preset time. It was used W, Mo and Ag materials for calibration, in the same parameters as the samples. 3. RESULTS AND DISCUSSION

Figure 3 shows all the experimental, limiting the channels that show the Zn-Kα and Zn- Kβ. As it can be seen, they are very similar and difficult to differ only looking for the intensities. However, it’s clear that from those spectrums, Zamak-1 has a more intense Zn peak than the others, as having more Zn.

Figura 3: EDXRF Spectrum of Zamak samples. Figure 4 shows Zn concentrations of the samples, provided by certificates. It can be observed that it is not possible that Zamak-1 has more Zn than the others samples of Zamak. In fact it should be one mixed with low peaks. It was expected that Zamak-3 would stand out from all samples. Even with certificates, we find that Zamak-1 it’s the sample with more Zn, and so we cannot rely in those certificates to differ the samples, although we could only see significant differences for one sample compared to the others.

Figure 4: Zn concentrations in samples, from certificates

4. CONCLUSIONS

It can be seen that the highest concentration (fig.3) it’s not from the one that we were expecting as in the certificates (fig.4). This happened probably due to the samples absorptions coefficients. To make any kind of comparison among the samples possible it would be necessary to perform absorption’s mathematical corrections, which includes the samples thickness, chemical composition and geometrical parameters of the XRF system. Nevertheless this is a preliminary work where EDXRF shows that it’s possible to be a quality control technique, with quick answers and easy arrangements, and as such, it could prevent problems in commercial applications of Zamak, as they could lead to surface irregularities into the objects, their destruction and even bring back the “zinc pest” by having lead impurities. However, to make a quantitative analysis, it’s necessary to do some matrix corrections on the analyzed samples because it’s not possible to distinguish them only by their EDXRF spectrum.

5. ACKNOWLEDGMENTS

We would like to thank CNPq and FAPERJ for the financial support. 6. REFERENCES

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