SU693191A1 - Method of determining linear expansion thermal coefficient - Google Patents

Description

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The invention relates to the field of measurement technology, specifically to methods for determining the temperature coefficient of linear expansion of materials (TKLR).

In modern technology, multilayer products are used, in particular double-layer (for example, bimetallic pipes, products with coatings, etc.) consisting of dissimilar materials. For successful operation of such products at elevated temperatures, thermal expansion must be taken into account, above each of the materials making up the product. In connection with this, the problem of determining layers of materials constituting the multilayer product ..

There is a known method for determining t.cl.r., including heating the sample, measuring its elongation and calculating the value of tls.l.r. ij. However, the 3Tt) T method is not applicable to bilayer products due to the no-no-picusti separation of the product layers, which is not always possible.

The closest in technical essence and the achieved effect to the proposed is the method of determination to l. a thin layer of material 2. This method consists in applying the studied material layer on two substrates with equal values of the modulus of elasticity, but with different and tight surfaces, heating two two-layer samples, and changing their flexural deformations. Amount tkl. The material layer under investigation is determined by calculation. So for substrates of the same geometry, tk. the test material is calculated by the formula

- .N

P1 g "-1 -

,

where 5 is the free end deviation

Claims (1)

the cantilever system, the indices 1-, 2 refer to the first and second headsets, since 3. The disadvantage of this method is that it is quite difficult to apply in the case of two-layer materials. To implement this method it is necessary to separate the layers of the sample, then to carry each layer into two. substrates with specific properties, and then test. But the separation of the layers n is always possible, at least, for-. difficult due to the need for additional devices. Obviously, it is also not easy to choose reference substrates for any investigated layers, the properties of which satisfy the condition of equality of their elastic moduli with a one-time difference in the cf. In addition, when using a known method, the number of tests is doubled in connection with doubling the number of test samples. . . The purpose of the invention is to simplify the process of selecting and manufacturing substrates and samples. This goal is achieved by making substrates of the same material, making samples with unequal ratios of the layer and substrate thicknesses and measuring the change in the length of one of the samples along the contact line. .Т. к.л.р. The materials under study are determined from the system of equations t (... () f ..fJlL 1 n Co (, - oC,). T..7 Crh + Lg), LEjVhJiJ.) - Tf-f. || - ( - |) -bc.-Tt where 5 - bending deformations of samples; D. - change in the length of the samples along the line of contact of the layers; “, E. - K.L.R. and the modulus of elasticity of the materials of the layers; h is the layer thickness; T is the heating temperature; t is the sample length; Jlil. f fE,. h, 1 EC, hj are known functions of dependence on the ratio of the elastic moduli and thickness of the layers, reflecting the geometry of the two-layer sample. Indices 1 ,. 2 relates to the first and second samples, respectively, and} 1, 2, the first and second layers in the two-layer sample. f) .1.4 K-solution of the riepBf.ix system of two equations allows to determine the difference between the classical ratio of the elastic moduli of the materials of the layers constituting the two-layer sample, and using the equilibrium coefficient, the absolute values of t.cl.r. each word Example. Definition t.cl.r. beryllium and beryllium oxides in the temperature range of 20-4OO C were carried out on two bilayer samples, obtained by anodizing beryllium strips of size 8Ox10xO, 23 mm. The ratio of the thicknesses of the beryllium oxide layer to the beryllium layer in the first and second samples was 0.35 and 0.15, respectively. A sample of a cantilever beam was used to measure sample bends. The bend of the free end and the elongation of the sample during heating were measured with a cathetometer. The exponent is a mentally determined bend of the first sample - 3 mm, the second 1, 3 mm, an increase in length - 0.24 mm, K.L. Value. beryllium and beryllium oxides, found from the solution of the above system of equations, where. . h. (H-ni) i (,) 2+ (c.7 ".and) (riL.Jb.-. (tV lE .hJ nu (0.15, vha / ir were 9, S" 1O ° degrees and 11.7–10 degrees, respectively. Using the proposed method for determining the frequency of flow makes it possible to determine because each layer of material in a two-layer sample without separation of layers, eliminates the use of reference substrates, reduces the number of test samples by half and gives possibility of simultaneous determination of the ratio of the elastic moduli of the layers of the materials of a two-layer sample. Formula of the invention A method for determining the thermal coefficient (coefficient of This is that the substance under study is applied in a layer on two substrates and the bending deformation of the samples and the temperature is measured, that is, that is, and that with, 1g} 1i. Irlus5 693.1. Item 16 sa selection and design of the substrate and on-i. Novikova S.I. Thermal expansion is different, they are made of single-solid substrates. M., Nauka, 1974, of the same material, make samples with unequal ratios of type and 2. USSR author's certificate of layer and substrate, and they include variation 5 No. 5О2301, cl. G O1N 25/16, 1976, the length of one of the samples along the line con-. tact layer-substrate. Zhuravlev G.I. Chemistry and Technology Sources of information, heat-resistant non-logic coatings, taken into account in examination L., Khim, 1975, p. 18-24,