Effects on trends in negative pressure of surface pre-treatments for the sealing plugs of a water-metal Berthelot tube system

Abstract

Trends in negative pressure over a few thousand cavitation events have been investigated for a Berthelot system comprising water/stainless steel/tube/sealing Ni plug in order to study the effects and extents of surface pre-treatments for the sealing metal, polishing, etching, and electroplating. The polishing and etching pre-treatments separated two kinds of cavitation nuclei on the metal surface; gases trapped within pores (crevices) (i) in the metal surface, and (ii) extending deep into the metal bulk. The latter, although much tougher, influenced negative pressure for a thousand cavitation events at most. The rise in negative pressure after a total of 1800 temperature cycles levelled off at around -115 bar (-11.5 MPa) irrespective of the surface finishes of the plugs. Electroplated plugs gave poor increasing trends owing to the co-deposited hydrogen. Impurity gases in the metal did limit the rise in negative pressure. These results, together with those reported before, have validated the authors extended gas-trapping crevice model, negative pressure is eventually limited by a supply of gas from sources in the metal bulk to surface crevices.

Thermodynamics of Negative Pressures in Liquids

“…Since then, several methods [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] have been developed to generate negative pressures in liquids. The attainable negative pressure can be even of a few hundreds of Mpa [4,23].…”

“…This is because a high pre-pressurization both promotes the disappearance of trapped gas bubbles in the crevices of the walls and helps to diffuse dissolved gas in the liquid. An even more efficient approach [21,22] uses many cycles of pressurizationdepressurization.…”

Stagnations of increasing trends in negative pressure with repeated cavitation in water/metal Berthelot tubes as a result of mechanical sealing

“…By observing trends in negative pressure for water/ stainless steel tube sealed with poly-crystalline metal plug Berthelot systems, we disclosed (1) negative pressures increased with the number of temperature cycles (cavitation history effect), though scattered wide, (2) the effect was interpreted by a gas-trapping crevice model supplemented with a gas-supply assumption (gas-being-replenished crevice model) and (3) de-gassing pre-treatments for plugs were effective to raise negative pressures higher than their surface pre-treatments alone, though maximum negative pressures were achieved only after several thousands of temperature cycles [9][10][11][12].…”

Thermobarometry for 4′-n-Octylbiphenyl-4-carbonitrile in Metal Tube Berthelot Method and Polymorphism in Crystalline Phase of 4′-n-Octylbiphenyl-4-carbonitrile Found through Cooling Paths in Negative-Pressure Range

“…2000 temperature cycles, 5) while their surface pretreatments improved the increasing trends in the negative pressure for earlier temperature cycles; however, the final values rarely exceeded À110 bar. 5,6) The time-consuming approach yielded the following results: (i) a negative pressure on the order of À200 bar was achieved for ethanol, benzene and xylene in a well-conditioned metal tube, (ii) negative pressures above À120 bar were achieved approximately in two thirds of the last 100 cycles, and (iii) À160 bar was maintained for 1 h. 7) The underlying aim was to facilitate investigations of the behaviour of organic liquids including polymer solutions under negative pressure. Environmental stress cracking (ESC) is a brittlelike failure that occurs when test pieces of a polymer are weakly stressed while immersed in nonsolvents of the polymer.…”