The two-stage increase in negative pressure with repeated cavitation for water in a metal Berthelot tube

The authors made a stainless steel tube with a copper plug to study the effects of cavitation history on negative pressure for a system of water in a metal Berthelot tube. The water and the copper plug were pre-treated for air purging. The system was alternatively heated and cooled over appropriate temperature ranges many times. In the Berthelot method, the negative pressure generated with failing temperature becomes highest just before cavitation for a single heating and cooling procedure (one temperature cycle). Negative pressures for respective temperature cycles, though scattered, exhibited an increasing trend through two stages, a steep stage for earlier cycles and a gradual stage for later cycles. A similar effect of the cavitation history persisted even in a series of temperature cycles after exchanges of water, so long as the same plug was used for sealing. The negative pressure -76 atm (-7.7 MPa), which is higher than the values ever reported for water in a metal tube, developed at 46 degrees C through two water exchanges after a total of 850 temperature cycles. The two-stage increase was considered to be caused by the successive fading of the weaker cavitation nuclei in the system.