Fabrication of Surface Layer Enriched with Zinc on AlSi17 Aluminium Cast Alloy by Hot-Dip Galvanizing

The paper deals with the fabrication of the surface layer enriched with Zn on AlSi17 aluminium alloy to modify the microstructure and surface properties of the alloy. The continuous surface layer was fabricated on the AlSi17 substrate by the hot-dip galvanizing of AlSi17 for 15min in a Zn bath heated to 450°C. The thickness of the layer was about 100 μm. The layer was characterised by a multi-component microstructure containing the regions of a solid solution of Al in Zn and dendrites of a eutectoid composed of a solid solution of Al in Zn and a solid solution of Zn in Al. In the layer, fine particles of Si with a regular shape were distributed. The results indicated that these Si particles formed by the action of Zn on the eutectic Si precipitations in the AlSi17 substrate. In the microstructure, large primary Si crystals and multi-phase precipitations, originating from the substrate, were also observed. The surface layer had much higher microhardness than the AlSi17 substrate. The results showed that hot-dip galvanizing can be used to modify the microstructure and properties of the surface layer of AlSi17. The study indicates the possibility of conducting further research on the fabrication of joints between AlSi17 and other metallic materials using a Zn interlayer fabricated by hot-dip galvanizing

Change in the Microstructure of AlSi10MgMn Alloy with Higher Iron Content Due to an Increase in the Amount of Nickel

Recycling of the materials often requires modification of the manufacturing processes or application of the techniques to eliminate impurities that enter the material during recycling process. The main and the most detrimental impurity of the secondary (recycled) aluminium alloy is iron. Low iron solubility in aluminium leads to formation of the significant amount of harmful intermetallic phases that decrease foundry and mechanical properties of the final castings. Elimination of the detrimental iron effects might be achieved by addition of some chemical elements to change morphology of the intermetallic phase or to reduce negative effects of the phase to alloy properties. Gradual increase in the amount of nickel in the AlSi10MgMn alloy with a higher iron content is described in the presented article. From the selected additions of nickel (0,1, 0,3 and 0,5 wt.% Ni), the most favourable results were achieved by the addition of 0,5 wt. % Ni. Structural analysis of all experimental alloys (without addition and with a gradual addition of Ni) and related changes in measuring tensile and hardness properties is present

Impact of Remelting on ZnAl4Cu3 Alloy with Addition of Cd on Selected Technological and Mechanical Properties

One of the main objectives in order to increase economic efficiency in foundries is to determine the ratio of the scrap material which can be used in the further manufacture. This factor is important for determining the final prices of products and their competitiveness, given that the prices of zinc on world markets have increased significantly in the recent years. This article deals with the possibilities of remelting the zinc foundry alloy ZnAl4Cu3 and also evaluates the effect of cadmium on selected properties. The main goal is to provide a comprehensive view of the influence of these two factors on selected mechanical properties, casting properties, and microstructure. An important part of the research is to point out the combined influence of given factors. The results of experiments confirmed that an addition of 3 wt.% of Cd has a significant impact on technological and mechanical properties. Fluidity values compared to the Cd-free alloy increased by 22.4%. In terms of mechanical properties, the influence of Cd on the tensile strength was most visible, with a decrease in average by 25 MPa

Production of zinc alloys castings by spin casting method

Vydáno chybně pod ISSN 1210-047

Effect of the pressed ceramic filters on the reoxidation process

Article is focused on reoxidation processes during filtration of aluminium alloys. Many of our experiments proven, that when using filtration media in gating system, reoxidation occurs. Main goal of this article is to point out reoxidation problems occurring during filtration of aluminium alloys. Reason to conduct this work was anomalies discovered by experimental casts, which pointed out that after filtration of primary alloys, small oxide films was detected. Oxides was absent, when we poured without filtration media. Simulation software ProCAST was used during our research

The Influence of Remelting on the Properties of AlSi9Cu3 Alloy with Higher Iron Content

This article aims to evaluate the influence of remelting on the experimental Al-Si-Cu type alloy with higher iron content on mechanical properties in relation to the resulting structure. The remelting or recycling process is one of the means of reducing the production costs of the forge plant. The experimental part deals with the analysis of the results of mechanical properties, structural analysis, and the process of crystallization of structural components and their changes due to the increased iron content caused by remelting at different states of the examined alloy. The effect of remelting and ageing on microstructure was observed using a combination of different analytical techniques (light microscopy, scanning electron microscopy (SEM), and upon deep etching and energy dispersive X-ray analysis (EDX)). Tensile strength and elongation tests point to the negative effect of alloying, a gradual increase in wt% Fe and a change in the morphology of the iron phases, which began to manifest significantly after the fourth remelting. The process of natural ageing has been shown to be effective only on alloys with a lower number of remelting cycles, whereas the application of artificial ageing has resulted in improved mechanical properties in all the test alloys

Effect of the pressed ceramic filters on the reoxidation process

Article is focused on reoxidation processes during filtration of aluminium alloys. Many of our experiments proven, that when using filtration media in gating system, reoxidation occurs. Main goal of this article is to point out reoxidation problems occurring during filtration of aluminium alloys. Reason to conduct this work was anomalies discovered by experimental casts, which pointed out that after filtration of primary alloys, small oxide films was detected. Oxides was absent, when we poured without filtration media. Simulation software ProCAST was used during our research