Fabrication Of Alumina Dispersion Strengthened Copper Powders And It’s Metal Injection Molding

Alumina dispersion strenghend copper was used widely because of it’s high strength and stability in high temperature, also the electrical conductivity and thermal conductivity. In this paper, the powder of alumina dispersion strenghend copper was firstly made by high energy milling, then successfully prepared the samples by Metal Injection Molding. The research of MIM was expected provid a relatively new process to produce alumina dispersion strenghend copper material with complicated shape and low cost.Alumina powder and copper powder were mixed by high energy milling, to ensure alumina powder fine and homogeneous in copper matrix by changing milling time, milling speed, process control agent content. Alumina dispersion strengthened copper was studied by scanning electron microscope, X-ray diffraction, metallurgical microscope, mechanical property, and the sintering sample’s density. The result showed that by extending the milling time, the grain refining and lattice distortion increased, the shape of copper changed from laminar, to near-spherical finally.6wt% Al2O3 after 270r/min and 15 hours milling, the composite showed the highest compress strength was 565 MPa and conductivity was 34%IACS. The efficiency was higher at a high speed than low speed. The flour extraction rate was high when there was addition of process control agent.The effect of alumina content to the density, microstructure, mechanical property and electrical conductivity was studied. The results showed that alumina was a barrier for the sintering densification.When the content of alumina raised, the density decreased, the consistency of 6%Al2O3 was 79.4%,2.5%Al2O3 was 85.9%,1.2% Al2O3 was 89.4%. When the content of alumina raised, the electrical conductivity decreased, the highest electrical conductivity was 50%IACS and the content of Al2O3 was 1.2%.The work used the wax based thermal plasticity binders. After mixing the 1.2%Al2O3/Cu powders with medium diameter 7μm and binders, the samples were injected in a injection machine about 150℃and 3.5MPa. Injected samples were solvent debond about 7 hours and then thermally debond respectively to remove all the binders, sintering temperature and time were researched. The results showed that the higher the temperature, the higher the density,1070℃vacuum sintering 2h, the consistency was 96%. The sintering time did’t have much influence on the size of grains,1050℃vacuum sintering 2 hours, the grain size was about 10～20μm; 1050℃vacuum sintering 4 hours was about 10～20μm.1050℃vacuum sintering 3h produced the sample with 97% consistency. So 1050℃vacuum sintering 3h was a good choice.