Study On Al₂O₃ Ceramic-6061 Aluminum Alloy-304 Stainless Steel Composite Structure Encapsulating Process

The metal-ceramic composite armor fully exploits the anti-ballistic advantages of ceramics and metals,and has broad application prospects.However,metal-composite armor is a systematic problem involving a variety of encapsulating materials.In view of the shortcomings and limitations of the current ceramic-metal composite armor preparation technology,in this paper,the encapsulating process of Al₂O₃ ceramic-6061 aluminum alloy-304 stainless steel composite structure was carried out by means of sintering encapsulating and pressure brazing and diffusion welding.The method of directly encapsulating Al₂O₃ ceramics by sintering 6061 aluminum alloy obtained tight joints under the research process.The shear strength of the joint increases with the increase of sintering temperature and the holding time,the best joint shear strength was up to 9.5 MPa,and the joint was broken in ceramics partly.The surface of the Al₂O₃ ceramic was pre-metallized by electroless nickel plating,and the dense and uniform Ni-P nickel layer was obtained.In the encapsulating nickel-plated Al₂O₃ ceramic joints by sintering 6061 aluminum alloy,Al and Ni atoms are diffused to form Ni-Al intermetallic compound.The joint interface structure is:6061 aluminum alloy/Al₃Ni/Al₃Ni₂/electroless nickel plating layer/Al₂O₃ ceramic,the joint strength value is significantly improved,the maximum is up to 15.4MPa.The densely distributed Al₁₈B₄O₃₃3 whiskers were grown on the surface of Al₂O₃ ceramics with H₃BO₃ and H₃BO₃+KCl as growth materials,and the growth mechanism of aluminum borate whiskers was well explained by S-L-S theory.In the joint of sintering encapsulating6061 aluminum alloy/Al₂O₃ whose surface has grown whiskers,whiskers are distributed between the ceramic and the aluminum alloy,and the strength value of the joints is significantly lower than that of directly encapsulating Al₂O₃ ceramics.The spherical aluminum alloy ball is wedged between the whiskers under the microscopic fracture of the aluminum alloy side joint,and the wettability of the aluminum alloy on the surface of the whisker is relatively poor.A method for preparing composite structures with simple process and higher efficiency is proposed.In the direct diffusion bonding 6061 aluminum alloy/304 stainless steel joints,Fe and Al atoms interdiffused and formed different types of Fe-Al intermetallic compounds,and the joints were broken in the diffusion reaction layer.The Fe-Al diffusion reaction layer and the Ag-Al eutectic layer are present in the addition of the Ag intermediate layer diffusion bonding6061 aluminum alloy/304 stainless steel joint structure.The presence of the intermediate layer retards the formation of Fe-Al intermetallic compounds,and the maximum shear strength of the joint is 31.2 MPa.The brazing 6061 aluminum alloy/Al₂O₃ ceramic joint with Al-Si-Mg solder is composed of Al-Si eutectic,and the joint strength value increases with the increase of welding temperature and the holding time.Brazing 6061 aluminum alloy/nickel-plated Al₂O₃ceramic joint consists of Al-Ni intermetallic compound and Al-Si eutectic structure.With the increase of temperature and the holding time,the liquid aluminum-silicon eutectic dissolves the electroless nickel plating layer seriously,the shear strength of the joint is gradually reduced.