The Microstructure And Corrosive Wear Behavior Of A New Kind Of High-Al Bronze

Abstract: a new kind of high-Al bronze Cu-14Al-x as die material applying in drawing and extruding stainless steel of plate heat exchanger was developed by the researchers in our laboratory. The melting and casting process, heat-treatment, microstructure transformation and wearing behavior of the alloy have been explored before.In this paper, the microstructure of the new kind of high-Al bronze was identified by means of X-ray diffraction(XRD), scanning electron microscope (SEM), electron probe microanalyzer (EPMA), electrolysis extraction and deep etching procedure. The results show that high-Al bronze is composed of a, β,K and γ2 phases and the amount of phases has been changed by heat-treatment; main content of Co is rich in strengthing phase K. Although the amount of K phase is slightly diminished after heat treatment, the improvement of composition homogeneity and less increment of iron content in matrix of alloy will result in raising its micro-hardness which has advantage of its wear resistance.The corrosion resistance and behavior of the high-Al bronze Cu-14%A1-X in 3.5%NaCl, 5%H₂SO₄,10%H₂SO₄ and 10%HCl solutions were investigated by using Static Immersing Corrosion test, scanning electron microscope (SEM) and electrochemical methods . The results show that the corrosion resistance of Cu-14%Al-X is good in these Different solutions; The corrosion rate rises with the temperature's increasing. The (α+γ₂) phase suffers a dealuminization attack superior to β'and K phases. After corrosion, the contents of Al and Mn reduce obviously, while the content of Cu increases, which shows that the high Al-bronze suffers dealuminization corrosion.The wear behavior and corrosive wear behavior of Cu-14%Al-X and other two Al-bronzes were examined in pin-on-disc reciprocating device. The friction coefficients were tested in multifunction wearing device, and their worn tracks and wear debris were observed in SEM. The results show that under the state of dry friction, the order of abrasive wear loss is heat treatment high-Al bronze < as-casting high-Al bronze < QA1 9-4< QA1 10-5-5. The corrosive wear loss of bronzes in 3.5% NaCl or 5%H₂SO₄ solutions is lower than that in dry sliding, i.e. the exhibition "negative" synergy between corrosion and wear. The lubricating effect of water is not obvious, and water plays the role of cooling the surface, so the friction coefficients in water is higher than that in dry friction, while the wear loss is lower.