postheadericon Cavitation

Changing of liquid to gas and suddenly back to liquid as a rapid collapse (implosion). Cavitation occurs when the pressure/temperature boiling point is reached, liquid turns to gas and then drops and the gas turns back to a liquid. Boiling water occurs at 212F at sea level pressure, seen as bubbles violently forming as the liquid turns to gas, however, at higher altitudes/lower pressures, water boils at a lower temperature. When the pressure drops (like inside a pump 'behind' the propeller), so does the required temperature drop to reach boiling and bubbles are violently formed, pressure returns causing the expanded liquid to gas to suddenly return to compressed liquid, tiny implosions and heat occur strong enough to erode metal.