Displacement of igniter and specimen materials in combustion of gas-free systems in a rigid shell

Combustion of pressed specimens of heterogeneous systems subjected to a constant axial mechanical load

“…After that, one can see a stable and expected de- crease in the observed burning rate and stabilization (after a small decrease) of the true burning rate at a level of ≈9.5 mm/sec, which is close to the burning rate of the specimens with clamped ends. The extreme nature of the dependence of the burning rate on the relative elongation agrees well with the result obtained earlier -an increase in the burning rate in the range Δl/l = 0-25% with a subsequent decrease at Δl/l > 25% in combustion experiments with specimens of the same mixture in a half-closed rigid shell using a thick igniting tablet with "yielding" slags [6]. This result, as was already noted in [6], agrees with the data of [22] on the dependence of the burning rate of the Ti + C system on the relative density of specimens; i.e., the relative density of the specimen in the combustion zone in our experiments, as a first approximation, changes in proportion to the relative change in the specimen length (with unchanged specimen diameter).…”

“…Furthermore, material displacement can be observed both at the combustion front and behind and ahead of the front [6][7][8][9][10].…”

“…The latter method was used in the present study. A heterogeneous Ti + C + 20% TiC mixture prepared in a ball mill was used [6]. This mixture was pressed into specimens of diameter 8 mm and height l equal to 4 or 7 mm using the procedure described in [17], which involves the formation of a paper ("blue ribbon" decalcified filter paper) shell on the cylindrical surface of the specimens.…”