Design Of Aluminum Matrix Composite For Neutron Shielding And The Study On Its Solderability To The Al₂O₃Ceramics

As a new kind of structural-functional integration material, aluminum matrix composites possess outstanding neutron and gamma-ray shielding performance and good mechanical properties. The application of Aluminum matrix composite is based on the tight connection to Al2O3ceramics. MNCP is applied to evaluate whether the mass fraction of W/ZrH2, material thickness or the neutron energy would have an influence on the neutron transmission coefficient in this essay, which, as a result, provides reliable theoretical proofs for the selection of70%Wp/Al composites as the new type of shielding composite. Meanwhile, this essay has researched on the solderability between70%Wp/Al composites and Al2O3ceramics. By the way of depositing metal coating on the surface of Wp/Al composites and Al2O3ceramics respectively by magnetron sputter ion plating method, an experiment of protective atmosphere soldering between this two materials with80wt%Au-20wt%Sn solder at340℃was carried out. This essay also analyses the impacts of soldering parameters, such as coating type, coating thickness and soldering temperature, etc., on shear strength of the materials.The results show as follows:(1) Increasing the mass fraction of W/ZrH2has a significant moderating effect on100keV intermediate energy neutron, which has little effect on14.1MeV fast neutron.(2) For both45%W/Al composites and45%ZrH2/Al composites, material thickness has a moderating effect on both100keV intermediate energy neutron and14.1MeV fast neutron.(3) The neutron transmission coefficient fluctuates with the increasing neutron energy. Both the45%W/A1composites and45%ZrH2/Al composites present a "concave" phenomenon at10keV-1MeV, because of the neutron cross section formants. In addition, a "half concave" phenomenon at100eV～1keV happens for45%W/Al composites. Besides, for the14.1MeV fast neutron,45%W/Al composites has superior neutron moderator capabilities than45%ZrH2/Al composites.(4)With the help of Ni/Au coating, a firm solder could be achieved between the70%Wp/Al composites and the Al2O3ceramics. Under this condition, the shear strength of the joint could be as high as16.94MPa. (5)The analysis shows that the fracture usually happens on the surface between the Al2O3ceramics and Au-Sn solder. The thickness of Ni、Au films play a crucial role on the joints strength between Wp/Al composites and Al2O3ceramics. The appropriate values of thickness are0.4-0.8μm and1.3-2.5μm, respectively. Moreover, metallurgical bonding between Ni/Al and Au/Al result in firm connections between70%Wp/Al composites and Au-Sn solder even if the Ni layer becomes thinner. Besides, increasing the thickness of Au layer or decreasing the thickness of Ni layer will improves the shear strength of joints, which would also lead to the expansion of the soldering line to some extent.