To obtain excellent strength, lightweight properties, resistance to heat and shock and sound absorbing qualities by forming a first layer from s fiber-reinforced ceramics porous body having a specified porosity, and forming a second layer from a same matrix porous body having a specified porosity and a structure, wherein pore diameters are decreased toward the surface, so that each layer has different densities.
A lightweight ceramics sound absorbing material 10 is composed of a first layer of fiber-reinforced ceramic porous body 11 having a porosity of 60-92%, and a second layer of a same matrix porous body 12 having a porosity of 70-95%. In the porous body 12 of a matrix single phase, an inclined and orientated pores present, wherein pore diameters are decreased toward a surface adjacent to a side contacting with the fiber-reinforced ceramic porous body. Thereby, strength is improved, development of cracks can be retarded by the inclined and orientated pores in the porous body 12, even if cracks generate locally, and development of cracks are inhibited and limited because of the porous body 11 presented on the surface. And excellent resistance to heat and shock, and strength can be obtained.
TAGAYA YOUKO
TAKENOUCHI TAKEYOSHI
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