The aim of the Master thesis was to analyse the influence of tool steel without and with a protective layer on the interaction between molten aluminium and tool steel. The kinetics of the formation of the interaction layer between the molten aluminium and the tool steel was studied using differential scanning calorimetry (DSC). These results revealed the high temperature resistance of the tool steel without and with protective layer in contact with the aluminium melt AlSi9Cu3. External factors such as erosion were not considered. Two tests were performed by placing a sandwich of specimens in the DSC machine, the lower one made of tool steel without and with protective coating and the upper one made of AlSi9Cu3 aluminium alloy. After the test, the samples were examined metallographically by analysing the thickness and type of the interacting layers using optical and scanning electron microscopy. In order to compare and validate the results obtained in the laboratory, we also analysed the tool from production and performed a microstructure analysis of the tool steel with and without a protective layer before and after the end of its service life. The surface of the tool steel in contact with the molten aluminium was analysed, focusing on the evaluation of the surface roughness and the thickness of the protective layer. In addition, the roughness of the products at the beginning, middle and end of the tool life was analysed.
From the results of the analyses performed, we conclude that the protective layer on the sample has done its job. In the case of specimens without a protective layer, an interaction and a composite layer are formed, while the interaction between the tool steel with a protective layer and the aluminium alloy did not occur. The usefulness of using a protective coating is also reflected in the roughness of the products, which remained about the same throughout the life of the tool with a protective coating, while it increased significantly over time when the tool without a protective coating was used.
|