PSI - Issue 28

Nina Ogoreltceva et al. / Procedia Structural Integrity 28 (2020) 1340–1346 Nina Ogoreltceva et al. / Structural Integrity Procedia 00 (2020) 000–000

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3. Results and discussion 3.1. Initial powders characterisation

The analysis of the position and intensity of diffraction lines indicates that the phase corresponds to a TiB 2 (ICDD Card No: 01-075-0967, 2019), the presence of any other foreign crystalline phase was not detected. The SEM micrograph and the particle size distributions for the investigated TD1 powder (98% of purity) are shown in Fig.1.

Fig. 1. Initial TD1 powder: (a) SEM-micrograph; (b) particle size distributions.

TD1 has a wide particle size distribution with an average particle size (d 0.5 ) of 10.2 μm and a Specific Surface Area (SSA) of 0.4 m 2 /g. The mixture of the TD2 (97.8 % of purity) and the TD3 (97.5% of purity) powders was used in order to investigate an effect of the initial powder characteristics on resulted the best combination of the coating composition workability and its properties such as density and open porosity.

Fig. 2. SEM-micrograph and particle size distributions of TD2 and TD3 powders.

For the TD2 powder a multimodal particle size distribution from 0.1 to 10 μm is observed with the average particle size d 0.5 = 2.6 μm, and SSA = 1.2 m 2 /g (Fig 2). The TD3 powder consists of particles are from 20 to 120 μm which form coarse aggregates characterized by irregular morphology. The powder has d 0.5 = 53.2 μm, SSA = 0.1 m 2 /g and does not contain fine fractions (particles smaller than 5 μm). 3.2. Laboratory experiments During the laboratory experiments in order to develop the TiB 2 -based protective coating, the relationships between the composition, the microstructure and properties of the coating were investigated.