PSI - Issue 37

I. Shardakov et al. / Procedia Structural Integrity 37 (2022) 1065–1072 I. Shardakov et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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The experiment according to the described technique was carried out at several values of the fluence (10 15 , 3  10 15 , 5  10 15 and 10 16 ion / cm 2 ) with an ion energy of 20 keV. In this case, for each value of the fluence, the experiment was repeated on 3 samples. This made it possible to carry out statistical processing of the experimental data. The study of the process of the appearance of cracks in the carbonized layer during uniaxial deformation of the samples was carried out using optical microscopy (digital optical 3D microscope Hirox KH-7700). Uniaxial deformation was carried out using a developed and created stretching device (Fig. 2). The figure shows the device with the sample fixed in grips, which is placed on the stage of the digital optical microscope. The experimental technique was as follows: 1) The sample, fixed in the grips of the device, was placed on the stage of the microscope; 2) Using a photograph taken before stretching, the initial state of the carbonized layer was assessed; the length of the sample was measured by the grips using a digital caliper; 3) Due to the movement of the traverse of the device, a certain level of uniaxial tension of the sample was achieved; this level was estimated by the change in the length of the sample using a digital caliper; 4) The state of the carbonized layer on the deformed sample was estimated from the photograph recording the appearance of cracks on the surface. According to the described technique, experiments were carried out for 12 samples treated with different of fluence.

Figure 2. A device for uniaxial tension of film samples mounted on the stage of an optical microscope

3. Results Fig. 3 shows the results of uniaxial deformation on a Testometric FS100 testing machine according to the described method for two different film samples in the initial state and after plasma treatment. The results are given in the coordinates "effective stress – axial deformation". Here, the effective stress was determined as the ratio of the tensile force P to the total cross-sectional area of the sample, in which the areas of the substrate and carbonized layers were taken into account. Axial deformation was determined from the change in the length of the sample due to the displacement of the grips of the testing machine. The information in Fig. 3 is an example of the initial data for determining the elastic modulus of the initial polymer (solid lines in the graphs), the effective modulus of the polymer with a carbonized layer according to the ratio (4) (dashed lines) and the modulus of the carbonized layer according to the ratio (3).