Surface Metallization Of Al₂O₃ Ceramic By Laser Heating Method And Preparation Of Flexible Conductive Film Utilizing Monodispersed Silver Particles

Laser beam has the advantages of high energy density,machining efficiency and precision.In this dissertation,a laser scanning method was developed to metalize the surface of Al2O3 ceramic.Especially,the preparation process of spherical monodisperse silver particles and its application in the preparation of flexible silver conductive film were explored.The materials were characterized by XRD,SEM,TEM and FI-IR.In this paper,the compact Cu metal layer was prepared on the surface of Al2O3 ceramic using CO2 laser beam.In order to improve the wettability of Al2O3-Cu,the surface of Al2O3 ceramic was modified by Cu2O powder firstly.The study found that Cu2O react with Al2O3 at high temperature to form modification layer on the surface of Al2O3 ceramic,which main content was CuAl2O4 and CuAlO2 and covered the surface of Al2O3 ceramic closely.During the laser scanning process,Al2O3 ceramic absorbed the energy of laser beam and melted the Cu particles and modification layer.Then,Cu wetted with the modification layer and melting connection occured.The Cu layer distributed on the surface of Al2O3 ceramic in the form of flat ball of 100-120 ?m in diameter.When the laser scannning power is 84 w and speed is 40 mm/s,Cu connected with Al2O3 ceramic closely,and the shear strength of Al2O3-Cu interface was 1.8 MPa.In order to improve the connection of Cu matal layer covering on the surface of Al2O3 ceramic,the secondary laser scanning process was carried out.After the secondary laser scanning process,the metal coverage of Al2O3 ceramic surface increased significantly and compact metal layer was formed.The resistivity of Cu metal layer increased rapidly with the increase of laser beam energy.When laser scanning power and speed is 60 w and 150 mm/s respectively,Cu metal layer covering on Al2O3 ceramic surface had good electrical conductivity.and the minimum resistivity was 3.8×10-7 ? m.On the basis of summarizing the method of fabricating flexible thin film,a new method,which had the advantages of rapid preparation process and aviable to prepare large size flexible silver film,was developed to prepare flexibile silver film utilizing monodisperse silver powder.Firstly,silver powder with controllable size,in the range of 1-5 ?m in diameter,was prepared by liquid phase reduction method.After modified by TEOS,the modified layer of non-crystalline SiO2,covering on the surface of silver particles,was formed.The thickness of modified layer is about 35 nm.and the silver powder had good dispersity and fluidity.After,the TEOS modified silver paricles was mixed with organic slurry to prepare silver past.The controllable thickness of Ag layer,on the surface of the Al2O3 ceramic substrate,was prepared sucessfully by regulating Spin Coater rotate speed.After heated at 900? for holding 60 min,Ag particles sintered and connected with each other,forming flexible silver film with three-dimensional network structure.The thickness of flexible silver film can be 8-50 ?m in thickness The resistivity of prepared flexible silver film was about 1.0×10-7 ?·m and the minimum value was 6.658×10-8 ?·m,which increase to a certain extent compared with pure silver.