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...C, and lager yeasts preferring temperatures in the range 8–14°C. The higher temperature for ales results in a faster fermentation, with more flavour compounds being produced. Lagers, however, take longer to ferment and have less flavour from the yeast. In Week 4 you will learn about a further role of yeast other than in the primary fermentation. Yeast is also actively...

...C. Tools and dies may be directly hardened from the salt bath. The carbides used are vanadium, niobium and chromium carbide. Vanadium carbide is preferred. The coating layer is pore-free and is formed by diffusion of the carbon atoms diffusing from the steel matrix. The thickness of the layer is controlled by the process time, bath temperature and composition of the base...

...C; considerably lower than CVD. If required, the workpiece can be heated, usually by radiant heaters. Processes are “line-of-sight”, necessitating rotation of the workpiece to produce even coatings, unlike CVD. The use of the sputter ion plating technique, in which the target source almost surrounds the workpiece, enables coatings to be deposited in an almost...

...c) is clamped between electrodes (b) and pressed against anvil electrode (a). An electric current is passed through the end of the bar, heating it by resistance heating between the electrodes. During the operation the hydraulic cylinder pushes the bar through the electrodes, causing it to upset. [Diagrams to demonstrate 'Upset forging' - see article] Manufacture: Upset...