Protected phases

A second effect was the tendency for protected phases to be formed. If a liquid having a composition somewhat on the CaO-rich side of the boundary between the CaO and CjA primary phase fields (Fig. 2.5) is cooled calcium oxide is initially deposited and the liquid composition moves away from CaO and towards that boundary. When the latter is reached, and assuming that equilibrium were to be maintained, calcium oxide would redissolve, C3A would be deposited, and the liquid composition would move along the boundary. In reality, the C3A quickly surrounds the particles of calcium oxide, which thus form a protected phase, effectively removed from the system. This can markedly affect the composition of the ferrite phase which is subsequently formed on further cooling. 

See colloid protective phase (2) detergent surface-active agent wetting agent. 

The current development in reversed-phase chromatography goes in the direction of sterically or chemically protected phases (shield), phases with hydrophilic endcapping (AQ, EPS) and hybrid phases (XTerra). 

More stable and protective phase/oxides (S FeOOH, a Fe203 Fe304) formed on weathering steels at Chennai and Jamshedpur with prolonged exposure as... 

Open-Phase Protection. Phase failure may be caused by a blown fuse, an open connection, or a broken line. If phase failure occurs while the motor is stopped, stator current will rise to a very high value while the motor remains stationary, and excessive heating may damage the windings. 

Reversed-Phase Protection. Phase-failure and phase-reversal relays are used to prevent the operation of elevators and industrial machinery to protect motors, machines, and personnel from potential hazards when phase reversal or loss occurs. Interchanging two phases of the supply of a three-phase induction motor will reverse its direction of rotation. 

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