PSI - Issue 20

A.A. Kychkin et al. / Procedia Structural Integrity 20 (2019) 185–189 A.A.Kychkin et al / Structural Integrity Procedia 00 (2019) 000–000

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Fig. 1. Change of mixture colour due to the time of ultrasonic impact: а ) – 0 min; b) – 60 min; c) – 120 min; d) – 240 min.

After dispersing, the sediment resistance of samples of mixture was studied by means of exposure of samples to normal conditions for 4 hours with the resultant value of their optical transparency to the light and sediment. It was determined that dispersion of mixture within 240 minutes contributes to the fact that the sample gets transparent regarding other samples and there is no sediment. Consequently, it's feasible to apply ultrasonic dispersing not less than within 240 minutes. To explore the influence of ultrafine silicon carbide powders on the properties of epoxy resin they produced some samples for compression tests (GOST 4651- 2014), bending tests (GOST 4648- 2014), impact strength tests (GOST 4647- 80) with different degree of filling, range, chosen in response to the equivalent results of the studies, conducted with ultrafine fillers of different nature. The tests were carried out on the universal machine INSTRON 3369 with the highest extreme loads 50 kN, the value of graduation 0,01 kN and strength measurer tolerance ±0,1 %. The results of testing can be seen in Fig. 2- 3. Analysis of the dependencies shows the undulating changes of properties, i.e. increases or reductions of the relevant characteristics happen depending on the amount of particles. Existence of inflection points reflects the change of the destruction mechanisms when crossing the critical concentration level. Obviously, close to 1% there are significant changes, concerning solid resin. It shows the sensitivity of the filled epoxy resin to the particle amount under conditions of compression and bending.

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b

Fig. 2. Dependence of stress (a) and modulus of elasticity (b) in bending on SiC amount