thermodynamics Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of the ...

, explosive boiling or phase explosion is a method whereby a superheated metastable liquid undergoes an explosive liquid-vapor phase transition into a stable two-phase state because of a massive homogeneous nucleation of vapor bubbles. This concept was pioneered by M. M. Martynyuk in 1976 and then later advanced by Fucke and Seydel.

Mechanism

Explosive boiling or phase explosion - p-T diagram

Explosive boiling can be best described by a p-T phase diagram. Figure on right shows a typical p-T phase diagram of a substance. The

binodal In thermodynamics, the binodal, also known as the coexistence curve or binodal curve, denotes the condition at which two distinct phases may coexist. Equivalently, it is the boundary between the set of conditions in which it is thermodynamicall ...

line or the coexistence curve is a thermodynamic state where at that specific temperature and pressure, liquid and vapor can coexist. The

spinodal In thermodynamics, the limit of local stability with respect to small fluctuations is clearly defined by the condition that the second derivative of Gibbs free energy is zero. : 0 The locus of these points (the inflection point within a G-x or G- ...

line on right is the boundary of absolute instability of a solution to decomposition into multiple phases. A typical heating process is shown using red ink. If the heating process is relatively slow, the liquid has enough time to relax to an equilibrium state and the liquid follows the binodal curve, the

Clausius–Clapeyron relation The Clausius–Clapeyron relation, named after Rudolf Clausius and Benoît Paul Émile Clapeyron, specifies the temperature dependence of pressure, most importantly vapor pressure, at a discontinuous phase transition between two phases of matter ...

is still valid. During this time heterogeneous evaporation occurs in the substance with bubbles nucleating from impurity sites, surfaces, grain boundaries etc. Fluctuation of thermodynamic properties near critical point

Fluctuation of thermodynamic properties near critical point

On the other hand, if the heating process is fast enough that the substance cannot reach binodal curve through heterogeneous boiling, the liquid becomes superheated with its temperature above

boiling point The boiling point of a substance is the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the surrounding envir ...

at a given pressure. System then shifts away from the binodal and continues to follow the red curve and thus approaches towards spinodal. Near the

critical temperature Critical or Critically may refer to: *Critical, or critical but stable, medical states **Critical, or intensive care medicine *Critical juncture, a discontinuous change studied in the social sciences. *Critical Software, a company specializing in ...

thermodynamic properties like specific heat, density varies rapidly as shown on the figure at right. Density and entropy undergoes largest fluctuation. During this time it is possible to have a large density fluctuation in a very small volume. This fluctuation of density results in the nucleation of a bubble. The bubble nucleation process occurs homogeneously everywhere in the substance. The rate of bubble nucleation and vapor sphere growth rate increases exponentially closer to the critical temperature. The increasing nucleation prevents the system from going to the spinodal. When the bubble radius reaches the critical size it continues to expand and eventually explodes resulting a mixture of gas and droplets which is termed as explosive boiling or phase explosion. At the beginning, explosive boiling was used by Martynyuk to calculate the critical temperature of metals. He used electric resistance to heat up metal wire. Later explosive boiling was found to occur while using ultra fast femtosecond laser ablation. Although this kind of explosive boiling should occur by any mechanism whereby the temperature of the liquid is rapidly raised close to the critical temperature of the substance.

References

{{Reflist Physical chemistry