Equipment for Measurement of Materials’ Strength at High Temperature

Special setups were developed for measuring the strength and plasticity of ceramic materials during bending, compression, tension, and creep and the endurance limit at high temperatures up to 3,000K in inert gasses or in a vacuum (Fig. 3.1).

When using the dynamometer, the relative measurement error of stresses rang­ing 0.4-1,000MN does not exceed 1 %. The measurement error of sample strain, estimated as support displacement difference, was 5%. This system was used for Russia’s first strength test for graphite and ZrC at 3,000 K in 1960. The PRV-203 system built by the Research institute of test machines (RITM, Moscow), originally developed for testing of large samples heated by tungsten heater up to 2,500 K in vac­uum (see Fig. 3.2), was subsequently reworked (in particular, the clamping fixture and dynamometer were redesigned) for bending test of smaller samples (2 x 2 x 25 mm) with stress measurement error of 2 % at the lower load limit of 0.2 MN. Sample strain (with 5 % measurement error) was estimated by support displacement as registered on the device diagram tape at a scale of 1:100.

In 1973, ordered by “Luch” the RITM has developed the electron beam machine EBM-402 for mechanical testing in vacuum at temperatures up to 3,300K. Sample surfaces were heated by scanning electron beams of two electron guns (see Fig. 3.2a). Samples were subjected to the load of 2-2,000 kgf with adjustable loading speed of 3 x 10-5 to 0.4 s-1. Sample strain was measured by extensometer connected to

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Fig.3.2 General view of the installation EBM-402 with electron beam heating (a) and the machine PRV-203 with the tungsten heater for creep measurement and long bending strength in vacuum or an inert atmosphere (b)

variable-induction sensor. Sample temperature was measured by the optical pyrom­eter, whereas the local temperature pulses in multiple points of the sample were registered by the photovoltaic device. The measurement error of the true sample temperature at 3,000K was ±86K.

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