Cathodic contact erosion due to short-duration gas breakdown arcs

Abstract

The erosion of palladium contacts due to gas breakdown arcs in air and in an activating environment (naphthalene vapour) has been studied. The rate of erosion in air was not constant with arc energy but increased almost linearly from about 0·1 to 1·5 cm3 erg−1 over an energy range of about 100 to 500 erg per discharge. Beyond this energy range a slower increase was observed. Under the activated conditions the erosion rate was much lower than in air (eg at 2000 erg the erosion rate in air was 1·65×10−14 cm3 erg−1 and with naphthalene activation the rate was 1·1×10−14 cm3 erg−1); however, a variation in the erosion rate with energy was also observed. The variation with energy is considered to be caused by part of the available erosion energy being used up in surface film decomposition.

Integral equation calculations and computer simulations of the static structure and ionic transport in molten thallium halides

“…Second, and this is particularly relevant for solid-state calculations, the TlX compounds fail to satisfy the Cauchy relation between the elastic constants, which rules out the use of pair potentials. In fact, for TlX c 12 is about twice the size of c 44 [19]. Nonetheless, we submit that our semiempirical potentials remain a useful tool in liquid-state calculations.…”

Oxide films on arc cathodes and their emission and erosion

“…In the studies which have been made of arcs of sufficiently short duration for the number and size of craters to be meaningful, there is one observation for which c, h, r and It have all been recorded. For a 2 x 10-5 J arc on a palladium cathode it has been found (Gray et al 1972) that c = 2 x 103, r -3 x lO-7m and h -4 x lO-7m (the value for h, in Gray et al(l972) has been corrected in a private communication). Since the arc energy ea=2x 10-5 J was calculated (Gray et a1 1972) from ea= 14It, where a minimum arc voltage of 14 was assumed, then It= 1.43 x 10-6 C. From equation (A2) mi= 1.59 x lO-I3 kg, and from equation (A3) mc=2.64 x 10-12 kg giving mifmc-0*06.…”

“…If the total arc current I flows for a time t (s) then the mass mi of cathode vapour returning to the cathode in ionized form is mi = Nm, I+ tie = 1.04 x 10-9 NIt kg (A21 where N is the number of atomic nucleons of the cathode material, mp is the proton mass, and e is the ionic charge. If during this arc duration of time t, a total of c craters of average radius r (m) and average depth h (m) are formed, then for craters which appear from SEM studies (Gray et al 1972) to approximate to a part of a sphere cut off by a plane, the mass of cathode material removed from the craters mc is mc = (ncSh/6) (h2 + 3r2)…”

Study on the erosion characteristics of copper‐carbon electrode pairs by DC air arc

“…The strong energy impact generated by the arc discharge leads to serious erosion of the electrode materials [6][7][8]. The interaction between the electrode and the arc is regarded as an important issue affecting the arc discharge behaviour and the electrode service life [9][10][11][12][13], which seriously threatens the safe and stable operation of the system and therefore has attracted wide attention of relevant scholars.…”