Porous calcium phosphate ceramic and method for producing same

1. A porous calcium phosphate ceramic body comprising a substrate having fine pores, and three-dimensional nanotunnel layers having pluralities of three-dimensionally connected nanotunnels formed on wall surfaces of said fine pores by mixing together calcium phosphate particles, a dispersant and water to form a slurry in a single dispersion state or near a single dispersion state, immersing said substrate in said slurry, and defoaming said slurry under reduced pressure, wherein said three-dimensional nanotunnel layers are formed in the fine pores inside the substrate, wherein a thickness of said three-dimensional nanotunnel layers is from 20 to 300 nm, wherein at least part of said nanotunnels have openings communicating with the fine pores of said substrate and said openings have an average diameter of 1 to 200 nm, and wherein the substrate and the three-dimensional nanotunnel layers are made from calcium phosphate.

2. The porous calcium phosphate ceramic body according to claim 1 , wherein said three-dimensional nanotunnel layers are formed on 5 to 100% of the wall surfaces of said fine pores.

3. The porous calcium phosphate ceramic body according to claim 1 , wherein said substrate has a porosity of 40 to 98%.

4. The porous calcium phosphate ceramic body according to claim 1 , wherein an atomic ratio of Ca/P in said three-dimensional nanotunnel layers is substantially equal to or smaller than that in said substrate.

5. The porous calcium phosphate ceramic body according to claim 1 , wherein the pores of the substrate have diameters of about 50 to 500 μm.

6. The porous calcium phosphate ceramic body according to claim 1 , wherein said dispersant is a nonionic surfactant.

7. A porous calcium phosphate ceramic body comprising a substrate having fine pores, and three-dimensional nanotunnel layers having pluralities of three-dimensionally connected nanotunnels formed on wall surfaces of said fine pores, wherein the three-dimensional nanotunnel layers are produced by a method comprising:

mixing together calcium phosphate particles, a dispersant and water to form a slurry in a single dispersion state or near a single dispersion state;

immersing the substrate in the slurry;

defoaming the slurry under reduced pressure;

drying the porous calcium phosphate ceramic body at a temperature below a boiling point of water, followed by a heat treatment at a temperature between 600 to 900° C.;

wherein the three-dimensional nanotunnel layers are formed in the fine pores inside the substrate;

a thickness of said three-dimensional nanotunnel layers is from 20 to 300 nm;

at least part of said nanotunnels have openings communicating with the fine pores of said substrate and said openings have an average diameter of 1 to 200 nm;

the three-dimensional nanotunnel layers are from on 5 to 70% of the wall surface of said fine pores;

a mass ratio of the three-dimensional nanotunnel layers to the ceramic body is from 0.001 to 0.05; and

the substrate and three-dimensional nanotunnel layers are made from calcium phosphate.