Abstract: Many of the engineering materials in use are not pure substances but contain two or more ingredients. There will be various interactive effects which can affect both the number of phases and the temperatures at which changes of phase occur. Firstly, what do we mean by the word phase? A phase may be defined as a portion of matter that is homogeneous. A pure substance may exist in three states, solid, liquid and vapour, each of these states being a single phase. The relationships between these states, or phases, for various conditions of temperature and pressure, can be shown on a simple diagram, a p-t diagram. Figure 11.1 is a p-t diagram, or phase diagram, for water. The bounding line between liquid and solid phases in this diagram is almost parallel with the ordinate, showing that an increase in pressure will have the effect of reducing slightly the temperature at which liquid and solid phases are in equilibrium with each other. Put in other words, the effect of a pressure change on the melting or freezing point is very small. The water phase diagram is a good example of a one-component system.
Publication Year: 1992
Publication Date: 1992-01-01
Language: en
Type: book-chapter
Indexed In: ['crossref']
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