Niobium powder, metal niobium powder, the formation of a dense oxide film on its surface with unidirectional conductive valve metal properties. The Nb2O5 oxide is a white powder with a purity of 99.999%. It is used to produce high purity lithium niobate crystals and special optical glass additives. The anodic oxide film has stable chemical properties, high resistivity, small leakage current and large dielectric constant.The specific capacitance of niobium powder used in capacitors is F·V/g (3300 ~ 3600), and the leakage current value is 1×10-3 cm A/(F·V). Reduction - hydrogenation method and sodium reduction method were used. Used in the manufacture of electrolytic capacitors and walkie-talkie and general industrial electrical equipment.
The purity of capacitor grade niobium powder has an important influence on the quality of anodic oxide film and leakage property of capacitor. The apparent density of niobium powder, Karl fischer average particle size, particle size distribution, grain shape characteristic is the important physical properties, capacitor anode manufacturing should choose according to the design specifications of the capacitor with appropriate apparent density, freund's average particle size, particle size distribution of niobium powder as raw material, through strict control of pressure density, sintering conditions, the oxide film formation process, thus obtained shrinkage rate is appropriate, high porosity, pore size distribution, and the right has enough capacity of capacitor anode, which has good performance capacitor products one of the important prerequisite.
The specific volume (CV) and dc leakage current (DCL) of the anode were decreased with the increase of sintering temperature. The volume shrinkage (SHV) and breakdown voltage of sintered body increase with the increase of sintering temperature. Energy-enabling voltage increased −− CV decreased −− DCL increased; With the increase of pressing density, under the condition that the diameter of anode block remains unchanged, the height of blank block decreases, CV decreases and DCL may also increase. Due to the inherent characteristics of niobium oxide film, niobium powder is generally suitable for the production of capacitors under 10 V. Niobium powder is sensitive to sintering temperature, so the process conditions of making capacitor anode with niobium powder can be determined.
