CREATION OF COMPOSITE BRONZES REINFORCED BY STEEL DENDRITES

2018 
The paper studies the group of composite bronzes, BrFNCA 9-4-1-1, BrFNA 12-7-1 and others where brittle Cu3Sn intermetallics are «replaced» by steel dendrites. The mass transfer of Fe, Ni, Co, Al between the matrix and dendrites in these bronzes is investigated. Dendrite dispersion depending on the methods used to produce these bronzes can be increased by a factor of 10, for example, in the vacuum casting process. The mechanical properties of BrFNCA samples (σв = 372 МPа, δ = 25 %, ψ = 42 %) are higher as compared with the BrO10 prototype: by 50 % in terms of σв hardness, and by 4–5 times in terms of δ and ψ plasticity. The coefficient of friction is lower than that of BrO10 by 20–30 %, and wear resistance is higher by an order of magnitude. The fact of a significant effect of the dendritic component dispersion on the BrFNA bronze wear rate is found. Thus, the wear rate for 1 μm and 10 μm dendrite cross sections is 0,002 and 0,025, respectively, and the coefficient of friction remains unchanged, i.e. it does not depend on dendrite dispersion. The whole set of mechanical, processing and service properties makes it possible to consider that the semicommercial tests of this new class of BrFNCA composite bronzes reinforced with H12C7A maraging dendrites for sliding friction units are justified and promising.
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