Abstract
Aluminum bronzes are the highest strength standard copper based alloys. For their combination of high strength, excellent corrosion and wear resistance these alloys have a wide acceptance in engineering applications, so studying their improvement still important. In the present study, a base aluminum bronze alloy with a chemical composition of (Cu – 11%Al) is prepared basing on powder metallurgy technique with a determined suitable compacting pressure of 400MPa, sintering for 1 hour in 920°C in a vacuum furnace (10-4 tor) , and then quenching from 950°C in cold water and tempered at 4500C for 2hrs. Graphite particles of 0.05 , 0.1 , 0.3 , 0.6 , 1 , and 3 weight percentages were added as reinforcing elements to the alloy. The influence of the graphite particles on physical, mechanical, and machining properties of the base alloy had been investigated. This included microstructure, hardness, compressive strength, and the roughness of the machined surface. To achieve the objective of the presented work, the tests included are: SEM analysis, XRF test, XRD analysis, microhardness test, compressive strength test, as well as the machining tests. The machining program is based on face turning with a constant depth of cut of 0.2 mm and using four cutting speeds of (80, 125, 250, and 400 rpm) for each of which four feed rates of (0.1, 0.18, 0.28, and 0.35 mm/rev) were used. The turning processes were carried out via a tool with a carbide tip type P10.
The study shows that an addition of 0.3wt% of graphite particles has the greatest effect on the properties of the studied aluminum bronze. The addition of 0.3wt% of graphite particles increases the hardness by (7.93%), the compressive strength by (11.62%). The results of the machining experiments show that such percentage of graphite particles reduces the surface roughness by (22.65% to 32.38%) when turning with the used machining conditions.