OPERATIONAL PROPERTIES OF CONSTRUCTION MATERIALS WITH PROTECTIVE COATINGS OBTAINED UNDER NON-STATIONARY TEMPERATURE CONDITIONS

The structure and phase composition of chromium-alloy coatings consisting of the following phases are investigated in the work: when boron doping the coating on brass C68700 consists of phases: Cu3Al, CuB, CuZn2 and zones of solid solution Cr, Al, B in copper; during titanium doping Cu3Al and CuAl phases in the transition zone: phases CuTi and CuTi2 When tested on A572 steels, in conditions of sliding friction, the best wear resistance among the considered protective coatings are doped with titanium and boron. Their wear resistance is 1,8 – 2,1 times higher than that of coatings obtained under isothermal conditions. Under non-stationary temperature conditions, the microhardness reaches the following values: when doped with boron H100 = 16500 – 17500 MPa, when doped with silicon H100 = 13500 – 14500 MPa, when doped with titanium H100 = 15000 – 16000 MPa. The obtained results correlate with the indicators of wear resistance. A comparative analysis of the corrosion resistance of protective coatings obtained under non-stationary temperature conditions and isothermal conditions shows that they have a weight loss of 1.7–2.1 times less. It was found that when tested in a 30% aqueous solution of sulfuric acid, all protective coatings have good stability. Thus, when doped with boron, the weight loss is 15,2 g/m2, при when doped with silicon - 10,8 g/m2, and when doped with titanium - – 9,9 g/m2.

Modification of boron nitride nanocages by titanium doping results unexpectedly in exohedral complexes

Despite their early experimental production and observation, the unambiguous molecular structures of metal-containing boron nitride (BN) nanocages still remain mysterious. It has been commonly assumed that this family of compounds has the metal atom confined inside the cage, just like their isoelectronic cousins, carbon metallofullerenes do. Here, we demonstrate that Ti(BN)n ($$n$$n = 12–24) complexes have, unexpectedly, an exohedral structure instead of an endohedral one, which could be verified by collision-induced dissociation experiments. The predicted global minimum structures exhibit some common bonding features accounting for their high stability, and could be readily synthesized under typical conditions for generating BN nanoclusters. The Ti doping dramatically changes not only the cage topology, but the arrangement of B and N atoms, endowing the resultant compounds with potential for $${\mathrm{CO}}_{2}$$CO2 capture and nitrogen fixation. These findings may expand or alter the understanding of BN nanostructures functionalized with other transition metals.