Influence of Ultrafine Additives of Intermetallides on the Structure, Mechanical, and Tribotechnical Properties of Sintered Tin Bronze

Abstract

The results of a study of the influence of the introduction of powders of intermetallic compounds of various compositions obtained by self-propagating high-temperature synthesis (SHS) with preliminary mechanical activation on the structure, mechanical, and tribological properties of sintered bronze are presented. It was found that the introduction of 0.2–0.5 wt % of nickel and titanium aluminides, both single-phase and two-phase, leads to an increase in the density and strength of sintered bronze; maximum strength is achieved with the introduction of 0.2 wt % aluminides. The dependence of the hardness of powder bronze on the amount and composition of the intermetallic compound differs from the dependence of strength; with the introduction of single-phase intermetallic compounds, the hardness increases with increasing additive content, and with two-phase intermetallic compounds it decreases. It has been shown that the introduction of aluminides ensures a refinement of the structure of the bronze during sintering, and at an additive content of 1 wt %, an increase in the amount of eutectoid (α + δ). The introduction of aluminides also has a positive effect on the tribological properties of sintered bronze. With the introduction of 0.5 wt % two-phase nickel aluminide and 0.2 wt % single-phase titanium aluminide, the seizure pressure and wear resistance increase by 2.8 times and 3.5 times, respectively. Adding 0.5 wt % of single-phase nickel, titanium, and iron aluminides allows reducing the friction coefficient to 0.009–0.011, and two-phase iron aluminide to 0.005. The introduction of iron aluminides most effectively increases the tribological properties of sintered bronze, so the seizure pressure increases to 10 MPa and wear resistance by almost 10 times. Aluminides help reduce the relief of the friction surface during adhesive wear of sintered bronze and the formation of microlacunae, which are additional reservoirs for lubrication. The smoothest friction surface and a higher content of microlacunae are observed in samples made of powder bronze with the addition of single-phase iron aluminide.