Research On Preparation Of Ni-BaTiO₃ Composite Particle By Spray Pyrolysis

Recently nickel internal electrode MLCC was widely used in military and civil electronic equipments because of low volume, large capacity, long lifetime, high reliability and low cost. While there were two problems must be solved in the co-sintering process of MLCC production:oxidation and sintering mismatch of Ni electrode. In this work, Ni-BaTiO3 composite powders were prepared by ultrasonic spray pyrolysis, aiming to get good morphology and crystallinity for the improvement of the anti-oxidative ability and sintering mismatch of Ni. The Ni-BaTiO3 composite powders were prepared by using titanium tetra-isopropoxide (TTIP), barium acetate, nickel nitrate, and urea as precursors in N2 atmosphere. In this paper, the thermal characteristic of precursor was analyzed, and the effect of different parameters on the preparation process of Ni-BaTiO3 composite powders was experimentally investigated. The morphology, crystallization behavior, element analysis, particle size and antioxidation of the products were characterized by SEM, XRD, EDS and DSC-TGA. The results indicated that high furnace temperature and Ni2+ concentration, low recombination agent dosage, solution feed rate and gas flow rate were beneficial for getting good-performance composite powders, and the optimum conditions were given as such furnace temperature 900℃, Ni2+ concentration 0.6mol·L-1, recombination agent dosage counted by BaTiO3 to single particle of 10% on weight, solution feed rate 1.5 ml·min-1, carrier gas flow rate 100L·h-1. Under the optimum experimental condition, spherical Ni-BaTiO3 composite powders with average size of 9.455μm, homogenous, uniform size distribution and good crystallinity could be achieved.In the meanwhile, this work discussed the effect of three additives-ethyl alcohol, urea and citric acid on the morphology of composite powders and found that little addition of citric acid (H3Cit) had tremendous influence on the morphology. It could not only restrain the production of pore and shell particles effectively, but also decrease the particle size and clean surface when the molar ratio of H3Cit to nickel nitrate is 0.3. The initial oxidation temperature of the composite nickel powder prepared under this conditions is 11℃higher than that of the unmodified nickel powder.