Development of Composite Bronzes Reinforced by Steel Dendrites

Аннотация

A group of composite bronzes BrZhNKA 9-4-1-1, BrZhNA 12-7-1, etc., has been studied. Brittle intermetallic compounds of the Cu₃Sn type are replaced by steel dendrites in them.. The mass transfer of Fe, Ni, Co, and Al between the matrix and dendrites in these bronzes is studied. The dispersity of dendrites depending on the production method of the mentioned alloys can be increased tenfold, for example, with the vacuum casting method. The mechanical properties of the samples of the BrZhNKA type (σ_u = 372 MPa, δ = 25%, and ψ = 42%) when compared with the BrO10 prototype are higher: hardness σ_u by 50%, plasticity δ and ψ by a factor of 4–5, and wear resistance by an order of magnitude; the coefficient of friction is 20–30% lower. The fact of the substantial influence of dispersity of the dendritic component on the wearing intensity of the bronze of the BrZhNA type is established. For example, the wearing intensity with the transversal section of dendrites of 1 and 10 μm is 0.002 and 0.025, respectively, which is an order of magnitude lower, while the coefficient of friction remains herewith invariable; i.e., it is independent of the dispersity of dendrites. A whole complex of mechanical, process, and service properties makes it possible to consider the half-industrial approval of this new class of composite bronzes of the BrZhNKA type reinforced by dendrites of N12K7Yu maraging steel for sliding friction units substantiated and promising.