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Destruction Mechanism of ZnAl4 as Cast Alloy Subjected to Cavitational Erosion Using Different Laboratory Stands

Jasionowski R., Polkowski W., Zasada D.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 1

19--24

EN

The main reason of a cavitational destruction is the mechanical action of cavitation pulses onto the material’s surface. The course of cavitation destruction process is very complex and depends on the physicochemical and structural features of a material. A resistance to cavitation destruction of the material increases with the increase of its mechanical strength, fatigue resistance as well as hardness. Nevertheless, the effect of structural features on the material’s cavitational resistance has been not fully clarified. In the present paper, the cavitation destruction of ZnAl4 as cast alloy was investigated on three laboratory stands: vibration, jet-impact and flow stands. The destruction mechanism of ZnAl4 as cast alloy subjected to cavitational erosion using various laboratory stands is shown in the present paper.

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Thermal Analysis of the ZnAl10 Alloy Modified by Ti Additions in AlTi5C0.15 and ZnTi3.2 Inoculants

Piwowarski G., Buraś J., Krajewski W. K., Krajewski P. K.

Archives of Foundry Engineering

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2014

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Vol. 14, iss. 4 spec.

101--106

EN

Cast alloys on the Zn matrix and of an increased Al content are characterised by good technological and mechanical properties, due to which they should meet special, more demanding requirements. However, the basic problem in these alloys technology, apart from a high tendency for gases pick-up and oxidation of liquid metals, is a tendency to form coarse-grained dendritic structures in castings solidifying in sand moulds, what - in turn - unfavourably influences their plastic properties [1, 2, 7, 11]. Therefore several treatments aimed at obtaining fine-grained structure and improving plastic properties are applied in these alloys technology. The presented study concerns the modification process of binary, middle-aluminium Zn alloys performed by additions of inoculants containing titanium and investigations of these modifications influence on the structure refinement degree. The Zn-10wt% Al (ZnAl10) alloy modified, before pouring into a sand mould, either by addition of the traditional inoculant i.e. Al-3wt% Ti-0.15wt% C (AlTi3C0.15 – TiCAl) or the new inoculant Zn-3.2wt% Ti (ZnTi3.2) was tested. Within investigations the thermal analysis was performed, especially cooling curves and their first derivatives, and also measurements by means of the differential scanning calorimetry (DSC), with a purpose of determining the modification influence on undercooling degree changes. Microstructures of the tested alloy were observed by the light microscopy (LM). The applied modification of middle-aluminium zinc alloys by AlTi3C0.15 and ZnTi3.2 inoculants causes a significant refinement of the alloy structure. Inoculants applied in investigations have a strong nucleating activity, which is confirmed by decreasing of undercooling and the temperature recalescence in cooling curves, which occurs simultaneously with grain refinements.

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Structure and selected properties of high-aluminium Zn alloy with silicon addition

Zyska A., Konopka Z., Łągiewka M., Nadolski M.

Archives of Foundry Engineering

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2011

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Vol. 11, iss. 3 spec.

261--264

EN

The results of examinations concerning the abrasive wear resistance, hardness, and thermal expansion of high-aluminium zinc alloys are presented. The examinations were carried out for five synthetic ZnAl28 alloys with variable silicon content ranging from 0.5% to 3.5%, and – for the purpose of comparison – for the standardised ZnAl28Cu4 alloy. It was found that silicon efficiently increases the tribological properties and decreases the coefficient of thermal expansion of zinc alloys. The most advantageous set of the examined properties is exhibited by the alloys containing over 2.5% Si. They are characterised by higher parameters as compared with the standardised alloy. Observations of microstructures reveal that silicon precipitates as a separate compact phase, and its morphology depends on the Si content in the alloy. The performed examinations show that silicon can satisfactorily replace copper in high aluminium Zn alloys, thus eliminating the problem of dimensional instability of castings.