The Kinetics of the Reactions of Beryllium with Oxygen and Nitrogen and the Effect of Oxide and Nitride Films on its Vapor Pressure

Abstract

A systematic study of the reaction of beryllium with oxygen is made over the temperature range of 350 ~ to 950~ The experimental data may be fitted by the parabolic rate law except for the initial period of the reaction. A plot of log K/T vs. 1/T gives an energy of activation of 50,300 calories per mole. A comparison of this rate data with other metals and alloys shows that vacuum-treated beryllium has the smallest parabolic reaction rate constant at 900~ of any metal or alloy that we have studied.The reaction with nitrogen is studied over the temperature range of 600 ~ to 925~ The data may be fitted by the parabolic rate law. A comparison with the oxygen reaction shows that the rate of reaction is somewhat smaller. A plot of log K/T vs. 1/T gives an energy of activation of 75,000 calories per mole.No reaction is observed with hydrogen over the temperature range of 300 ~ to 882~ A study of the vapor pressure of beryllium and the influence of oxide and nitride films is made using the Langmuir method. Excellent agreement is found for the vacuumtreated specimens with the recent results of Holden, Speiser, and Johnston. Oxide films exert a strong effect in reducing the vapor pressure, the effect varying as the square root of the oxide thickness. A film of 99 micrograms per cm ~ lowers the vapor pressure 100-fold.

Proposed beryllium metal bounding airborne release fractions (ARFs)/rates (ARRs) and respirable fractions (RFs) for DOE facility accidents analyses

“…8 @ 1,500 8C and 1-atm O 2 , >50% of the specimen oxidized within 15 min [weight/size of specimen not given]. 21 At the bp of beryllium, oxidation is rapid and the oxide forms a porous coat (corroborates characteristics of oxide depend on temperature during formation) and airborne release depends on the degree of mechanical disruption by external action. 23 At temperatures >mp oxide ($2,547 8C), the oxide layer is severely disrupted and berylliumvapors condense to d G 1-mm particles in the vapor state .…”

“…Experimental results have shown that the oxidation of beryllium is controlled by the release of beryllium vapor through the ''blue oxide'' layer. 15,[19][20][21]23 The airborne release of significant amounts of the beryllium oxide is primarily concerned with the potential conditions that may result in accelerated oxidation and ignition of the beryllium handled and processed within non-reactor, nuclear facilities. The oxidation process is affected by many parameters that may increase the rate of beryllium metal vapor.…”

“…''Reaction products were found a considerable distance from the beryllium sample''. 21 Experimental observations are that much of the high-temperature oxidation occurs in the vapor state away from particle surface -oxidation products are airborne at creation, and are fine drops or rods in the respirable size range. 8 Approximately 60% of the oxide from ignition of an isolated particle remains with the particle, as concluded by Macek 20 : ''The observed sizes of the spheres indicate that a large fraction of the beryllium may end up in the massive central particle -about 60%, if the terminal size of the oxide is the same as that of the original metal particles.…”

“…19 ; 0.2% [0.002 fraction] of 0.5-g sections of thin Be rods oxidized after 80-min @ 1,185 8C. 21 Burn time of a [d G ] 35-mm particle in an atmosphere of O 2 is 3-4-ms 15 : at the bp of beryllium, oxidation is rapid and forms a porous coat [corroborates characteristics of oxide depend on temperature during formation] of agglomerates of particles in the respirable size range . .…”

Deuterium retention and out-gassing from beryllium oxide on beryllium

“…Gulbransen and Andrew [ 11 ] have examined the kinetics of Be oxidation by measuring the weight gain during heating in oxygen with a vacuum microbalance. They observed that at constant temperature the oxidation rate follows a parabolic time dependence indicating that diffusion of Be through the oxide is the rate determining process.…”