Composite material
AssigneeABB Research Ltd.
InventorsFelix Greuter, Ralf Strumpler
Life of this patent
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Abstract
A varistor and a PTC resistor formed from a composite material containing a polymer matrix and a filler. The varistor experiences two nonlinear changes caused by the current due to applied voltage, the varistor comprising a composite material comprising a filler and a polymer matrix, the filler consisting of particles of grained microstructure. The PTC resistor experiences a first nonlinear dependency of resistivity at a first PTC temperature resulting from an interaction of the filler and the polymer matrix and a second nonlinear dependency of resistivity at a second, lower PTC temperature resulting from the filler.
Claims11
A varistor which limits an applied voltage as a result of a first nonlinear dependence on a current carried by the varistor due to the applied voltage, the varistor consuming power and being based on a composite material comprising a filler and a matrix which embeds the filler, the filler consisting of particles of grained microstructure, and the varistor limiting applied power above a critical current level as a result of a second nonlinear dependence of the current on the applied voltage, wherein the particles of grained microstructure are formed by a process selected from the group consisting of comminuting a sintered ceramic, comminuting a polycrystalline semiconductor, spray drying a suspension and calcining the spray-dried particles, spray drying a solution and calcining the spray-dried particles, spray-drying a suspension and sintering the spray-dried particles, and spray drying a solution and sintering the spray-dried particles.
A PTC resistor which is based on a composite material comprising a filler and a polymer matrix which embeds the filler, an interaction of the polymer with the filler being effective for limiting an applied current as a result of a first nonlinear dependence of resistivity on a first PTC temperature, the filler comprising an electrically conducting first material whose resistivity depends nonlinearily on the temperature, and wherein the filler is effective in limitation of the applied current as a result of the PTC resistor having a second nonlinear dependence of resistivity on a second PTC temperature which is lower than said first PTC temperature.
Dependencies are inferred from the claim text.