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摘要
This work reports the processing of bronze foams manufactured by using the powder metallurgy method known as Sintering Dissolution Process. During the sintering step, a device with controlled atmosphere separated from the heating furnace was employed to avoid the quick oxidation of metal particles. The device allows to control its internal atmosphere with an inert gas avoiding the employment of a controlled atmosphere furnace (a furnace of this kind incorporates the heating and the control atmosphere systems itself). The metal used for the present study was bronze powders with a composition of 85%Cu-15%Sn, similar to 8.7g/cm(3) in density, and particle size of 74 mu m. Spherical carbamide (CH4N2O) with particle size of similar to 1 mm was chosen as Space Holder Particles (SHP). The maximum porosity P-f and minimum density rho(f) values were 42.8% and 3.61g/cm(3), respectively. As the carbamide content is increased, the bronze powders content is diminished and consequently rho(f) is increased and rho(f) is diminished, as it would logically be expected. The minimum obtained rho(f) value corresponds only to 41.4 % of the bronze density (similar to 8.7g/cm(3)). On the other hand, the plots of stress sigma vs strain epsilon indicated o max values between 26.86 and 8.45 MPa (20 and 35%vol. of carbamide, respectively). These obtained values indicate a good metallurgical bond among particles, caused by the uniaxial compression step and sintering at the correct T-s, previously determined (580 degrees C). The sigma(max) decreases as the SHP content increases, which is due to a significant amount of porosity generated by the SHP dissolution and by the inclusion of void spaces among the metal particles; the both of them imply a lower area supporting the load, and consequently a reduction in a sigma(max) value for the samples. The results are interpreted in terms of increase and decrease of the carbamide and the bronze powder content in the sample, respectively.
- 出版日期2018
