Research On The Process Parameters Of Laser Cladding And Interficial Products Of SiC Fiber Reinforced Ti-6Al-4V

SiCf/Ti-6Al-4V composite material,as an ideal aerospace material,combines the excellent properties of SiC fibers and titanium matrix.However,the traditional preparation process has many limitations.A new manufacturing technology named Laser Cladding&Laminated Depositon is proposed in this paper,based on the technologys of laminated solid manufacturing and laser cladding deposition.The surface treatment of fibers,laser cladding process parameters and interfacial products between the SiC fibers and matrix were studied.The decomposition of SiC fibers with uncoated,C-coated,Cu-coated and Ti-6Al-4V-coated under laser was studied.The protective effects of different coatings on fibers are as follows:Ti-6Al-4V coating>Cu coating>C coating>no coating.The optimum technological parameters for electroless copper plating are NaOH addition of2.5 g and reaction time of 60 min.The shielding gas flow,defocusing amount,powder feeding rate,laser power and scanning speed on the decomposition of SiC fibers were studied,in view of the decomposition of SiC fibers under laser.The results show that the optimum parameters for shielding gas flow and defocusing amount are 11 L/min and 1 mm,respectively;when the laser power is 225-300W,scanning speed is greater than 3 mm/s,SiC fibers do not decompose;when laser power is 300-330 W,scanning speed is greater than 4mm/s,SiC fibers do not decompose;when laser power is 330-360 W and scanning speed is greater than 6 mm/s,SiC fibers do not decompose;when laser power is 360-400 W and scanning speed is greater than 20 mm/s,SiC fibers do not decompose;When the laser power is greater than 400 W,the fibers are completely decomposed.The smaller the laser power is,the faster the scanning speed is,the more intact the SiC fibers are.The optimized process parameters provide a reference for the future forming.The interface behaviors between Ti-6Al-4V matrix and the SiC fibers with C coating,Cu coating and Ti-6Al-4V coating were studied.For the C-coated SiC_f/Ti-6Al-4V,when the laser power is 300W and the scanning speed is 3mm/s,the interfacial products are C coating,Ti₅Si₃ and TiC|Ti₅Si?C?₃ and TiC|Ti₅Si?C?₃ and TiC in the upper reaction zone of the fiber and matrix.In the lower reaction zone of the fiber and matrix,the interfacial products are C coating,Ti₅Si₄ and TiC|TiC and Ti₅Si₃|TiC and Ti5Si3;When the laser power is 300 W and the scanning speed is 20 mm/s,the interfacial products are C coating,TiSi₂ and TiC|TiC.For the Cu-coated SiC_f/Ti-6Al-4V,the bonding force between the Cu coating and the fiber is extremely weak,and spalling occurs in the preparation of the composite materials.For the Ti-6Al-4V-coated SiCf/Ti-6Al-4V,the interface products are C coating,Ti5Si4 and TiC|TiC.Comparing with other coatings of SiC fiber,the SiC fibers with Ti-6Al-4V coating,as the most ideal coating,have thinner reaction layer,simple and stable reaction products.