Image Number 2 for United States Patent #8119206.
A method of forming a negative coefficient of thermal expansion particle includes flattening a hollow sphere made of a first material, annealing the flattened hollow sphere at a reference temperature above a predetermined maximum use temperature to set a stress minimum of the flattened hollow sphere, and forming a coating made of a second material on the flattened hollow sphere at the reference temperature, the second material having a lower coefficient of thermal expansion than that of the first material, the negative coefficient of thermal expansion particle characterized by volumetric contraction when heated.
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