Microstructural, Mechanical and Tribological Characterisation of CVD and PVD Coatings for Metal Cutting Applications

The present thesis focuses on characterisation of microstructure and the resulting mechanical and tribological properties of CVD and PVD coatings used in metal cutting applications. These thin and hard coatings are designed to improve the tribological performance of cutting tools which in metal cutting operations may result in improved cutting performance, lower energy consumption, lower production costs and lower impact on the environment.  In order to increase the understanding of the tribological behaviour of the coating systems a number of friction and wear tests have been performed and evaluated by post-test microscopy and surface analysis. Much of the work has focused on coating cohesive and adhesive strength, surface fatigue resistance, abrasive wear resistance and friction and wear behaviour under sliding contact and metal cutting conditions. The results show that the CVD deposition of accurate crystallographic phases, e.g. α-Al2O3 rather than κ-Al2O3, textures and multilayer structures can increase the wear resistance of Al2O3. However, the characteristics of the interfaces, e.g. topography as well as interfacial porosity, have a strong impact on coating adhesion and consequently on the resulting properties.  Through the deposition of well designed bonding and template layer structures the above problems may be eliminated. Also, the presence of macro-particles in PVD coatings may have a significant impact on the interfacial adhesive strength, increasing the tendency to coating spalling and lowering the surface fatigue resistance, as well as increasing the friction in sliding contacts. Finally, the CVD-Al2O3 coating topography influences the contact conditions in sliding as well as in metal cutting. In summary, the work illuminates the importance of understanding the relationships between deposition process parameters, composition and microstructure, resulting properties and tribological performance of CVD and PVD coatings and how this knowledge can be used to develop the coating materials of tomorrow.

English product names and descriptions in two Swedish supermarkets : A quantitative and qualitative analysis

This study aimed to investigate what proportion of two household staples, soap and crispbread products, in two Swedish supermarkets had English product names or descriptions, and attempted a qualitative analysis of the English language used. Out of the Swedish brands, 54-62% of the soap products had names and/or product descriptions containing English, compared to 13-15% of the crispbread; these differences were in line with previous research, suggesting English is used more to market certain product groups than other ones. Earlier studies have also proposed that English could be considered an ‘elite’ language in Sweden, and it might thus be more commonly found on more exclusive/expensive products, or in the supermarket primarily aiming at higher-income customers. However, the differences between the two supermarkets, and between the more and less expensive products, were not great enough for any firm conclusions. When products had a mixture of languages on the label, English was most often used for product names or part of names, not so often for product descriptions. Further studies with a larger amount of data would be required for more reliable conclusions, especially for the qualitative analyses. It would also be interesting to investigate customers’ attitudes towards the use of English on product labels.