Fiber Bragg Grating Metallization And The Welding Packaged Smart Structure

Fiber Bragg grating (FBG) has a potential to be widely used in engineering for itssmall size, light weight, simple structure and monitoring ability of realizing distribute,real-time and permanent. Metallized FBG has the ability of high temperatureresistance and weldability. Optical fiber smart metal structure can be achieved afterembedding FBG into the metal matrix and structure by means of metallization andwelding methods. Optical fiber smart metal structure keeps the ability of real-timemonitoring for the internal strain and temperature. The main contents in this study areas follows:1). Electroless plating of Cu, Ni-P and Ni-Zn-P on the surface of FBG wereinvestigated. The coating contents of FBG were pure crystalline copper, amorphousNi-P alloy with81%of nickel with and amorphous Ni-Zn-P alloy with6.3%of zinc,respectively. The temperature sensitivities of FBG after electroless Cu, Ni-P andNi-Zn-P were enhanced1.44,1.22and1.19times than that of the naked FBG,respectively.2). The process of electroless plating and electroplating zinc for FBG was studied.The bright coating of pure crystalline zinc was obtained after electroless Zinc platingin the acidic zinc sulfate solution with the process parameters of sulfate250g/L,15g/L ammonium chloride, boric acid30g/L and appropriate amount of sodiumdodecyl sulfate. The temperature sensitivity of FBG after electroplating zinc wasenhanced over5times than that of naked FBG. Temperature sensing stability testshowed that FBG as temperature sensor after electroplating zinc was better than thenaked FBG when used at room temperature.3). A smart metal structure was obtained after embedding metallized FBG intostainless steel plate by the laser welding method. A fixed end beam and a cantileverbeam for fixing stainless steel plate were designed and fabricated. With the metallizedFBG of electroplating zinc as temperature compensation, the two beams were testedfor strain sensing under the constant and variable temperatures. The results showedthat the wavelength of the embedded FBG presented a good linear relationship overthe strain of the smart metal structure.