The reactivity of NbC (single crystal and polycrystalline), TiC (single cry
stal and polycrystalline), and polycrystalline ZrC in the temperature range
from ambient to 1020 degreesC and at oxygen partial pressures from 0.07 to
9 Pa is reported. The reactivities of the principal (hkl) planes of TIC as
well as the polycrystal are also measured at 0.8 Pa of O-2. The reactivity
ratio order is 1.0, 1.2, and 1.9, respectively, for (111), (100), and (110
) planes. Under these conditions, laths at right angle of epitaxial rutile
were observed. The comparison of the reactivity between NbC(100) and polycr
ystalline NbC has been determined and some tentative data are given on the
reactivities of the other planes. The reactivity at higher oxygen partial p
ressures was also measured for TiC(111) and in these conditions a well-defi
ned TiC-rutile ceramic to ceramic joint has been obtained. The reactivity a
nd iii situ electrical resistivity measurements on polycrystalline TIC and
ZrC, both as received and high temperature, high vacuum treated, are presen
ted. Large differences in the reactivity hystereses were found. The same re
sult was not found in the behavior of the resistivity. (C) 2001 The Electro
chemical Society.