• Phase transformations at heating of Sn–Ni–Zn powders obtained by cementation from solutions

    Materials Science. Non-Equilibrium Phase Transformations., Vol. 5 (2019), Issue 3, pg(s) 99-101

    The low-temperature method of Sn–Ni–Zn powders synthesis by cementation of tin and nickel with zinc powder from acidic solutions with the formation of “zinc core – porous nickel shell – external tin layer” structures has been proposed. The method provides metals ratio control in wide ranges (7–41 at. % of tin, 38–86 at. % of nickel and 7–24 at. % of zinc) by variation of the process duration. X-ray phase analysis data give evidence on the presence of β-Sn and Zn phases as well as NiZn3 and NiSn intermetallics in the powders obtained. Differential scanning calorimetry data show the availability of Sn–Zn eutectic with the melting point at 171.2 °C in the powders with high tin content (30–40 at. %). The formation of the ternary intermetallic τ1 phase (Ni3+xSn4Zn) has been established to occur as a result of the powders heating at 260 °C. The discovered low-temperature phase transformation in Sn–Ni–Zn system at 260 °C is of interest for electronic equipment assembly processes that include consecutive stages of soldering and resoldering.

  • MATERIALS

    FORMATION OF NEAR-NANO SIZE TiB2-TiN-Al2O3 POWDER BY SHS

    Machines. Technologies. Materials., Vol. 10 (2016), Issue 11, pg(s) 49-51

    Formation of TiB2 , TiN and Al2O3 powder mixtures were obtained through self-propagating high-temperature synthesis (SHS), starting from TiO2 + BN + Al mixtures. As a diluent, NaCl was added in 0-40 wt% range to the starting mixture in order to refine the size of the formed particles. Thermochemical calculations were performed by Factsage software. The products were subjected to XRD, SEM and particle size analyses. Intended reaction products were obtained in the TiB2, TiN and Al2O3 system according to XRD analyses, with no cross reaction products. The crystallite size of the products decreased with the increasing amount of NaCl according to the broadening of the peaks on the XRD patterns of the products. Particle size measurements revealed that near-nano size particles were formed. A decrease in the adiabatic temperature was calculated, a decrease in the velocity of the SHS wave front was observed and a decrease in the particle size of the obtained products was measured as a result of the increase in the diluent amount.

  • ION-PLASMA HARDENING OF A TITANIUM ALLOY OT4-1

    Materials Science. Non-Equilibrium Phase Transformations., Vol. 1 (2015), Issue 1, pg(s) 55-58

    The paper is devoted to studying the influence of technological process parameters of deposition on the composition, structure and strength characteristics of TiN coatings on titanium alloy OT4-1. The TiN coatings were deposited by a vacuum-arc evaporator. In addition, the influence of the type of layers formation on microhardness and wear resistance of TiN layers and a metal substrate is presented.