黒鉛製品の破壊に対する温度影響について

概要

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Three kinds of graphite products, two non-permeative graphite (F and S) and one ordinary graphite (E), were tested under compression, bending and wedge indentation at various temperature. The specimens were tested in a bath filled with cooled alcohol or heated soya-bean oil, and the test temperature was regulated between -50℃ and 200℃. Under low temperature, the compressive strength σ_c of F and S is mainly governed by critical tensile stress σ_0, which is assumed to be equal to σ_0/1.5, and σ_b is the strength obtained from the bending tests. Under higher temperature, on the other hand, σ_c of these two products is governed by critical shearing stress τ_0. The fractured surfaces of these two products show brittle appearance under low temperature, but as temperature rises they tend to show ductile appearance. The wedge indentation strength σ_s, shows nearly equal tendency as σ_c, but the bending strength σ_b under higher temperature considerably differs from τ_0 in its temperature gradient. The critical tensile stress σ_0 and the critical shearing stress τ_0 are expressed as follows: σ_0=Ae^<S/T> τ_0=Be^<U/T> (S>U) where A, B, S, U are material constants and T is absolute temperature. Material E shows no temperature effect up to 200℃, and always shows brittle fracture.
宇宙航空研究開発機構の論文
1958-02-28