What is claimed is:
1. A light weight foam block being rectangular in shape and having horizontal and vertical pairs of tongues and grooves around its perimeter that enable it to interlock with horizontally and vertically adjacent blocks for construction of mine stoppings.
2. Block of claim 1 wherein the foam is a foamable plastic material.
3. Block of claim 1 wherein the foam is polyurethane.
4. Block of claim 1 wherein the foam is polyisocyanurate.
5. Block of claim 1 wherein the foam is phenolic.
6. Block of claim 1 wherein the foam is polyester.
7. Block of claim 1 wherein stopping wall is coated by a fireproof coating.
8. Block of claim 1 wherein the foam is fire proof and does not need a coating.
9. Block of claim 1 wherein the foam is made fire proof by adding silicates.
10. Block of claim 1 wherein the foam is reinforced with glass fibers.
11. Block of claim 1 wherein the foam is reinforced by matrix material.
12. Block of claim 1 wherein the block is reinforced by an integral skin.
13. Block of claim 1 wherein the block has only horizontal tongue and groove.
14. Block of claim 1 placed in a vertical position to construct a stopping wall.
15. Block of claim 1 wherein an adhesive is applied to tongues and grooves.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A magnetic recording medium, comprising a magnetic recording film in which a magnetic region is dispersed in a non-magnetic region, wherein:
the magnetic region includes a first magnetic portion with a coercive force and a second magnetic portion with a coercive force smaller than that of the first magnetic portion; and
the first magnetic portion and the second magnetic portion are laminated in a direction parallel to a film surface of the magnetic recording film.
2. The magnetic recording medium according to claim 1, wherein the first magnetic portion comprises a hard magnetic material; and the second magnetic portion comprises a soft magnetic material.
3. The magnetic recording medium according to claim 1, wherein the magnetic region is provided such that the second magnetic portion covers a periphery of the first magnetic portion.
4. The magnetic recording medium according to claim 1, wherein the magnetic region is provided such that the first magnetic portion covers a periphery of the second magnetic portion.
5. The magnetic recording medium according to claim 1, wherein an average magnetic anisotropic energy density of the second magnetic portion comprising the soft magnetic material is half or less as an average magnetic anisotropic energy density of the first magnetic portion comprising the hard magnetic material.
6. The magnetic recording medium according to claim 1, wherein a ratio k=Ku2Ku1 of an average magnetic anisotropic energy density Ku2 of the second magnetic portion comprising the soft magnetic material to an average magnetic anisotropic energy density Ku1 of the first magnetic portion comprising the hard magnetic material is smaller than a ratio \u03bc=Ms2Ms1 of an average saturation magnetization Ms2 of the second magnetic portion to an average saturation magnetization Ms1 of the first magnetic portion.
7. The magnetic recording medium according to claim 3, wherein:
the magnetic region is provided such that the second magnetic portion comprising a soft magnetic material covers the periphery of the first magnetic portion comprising a hard magnetic material;
a radius of a cross-section in a direction parallel to a film surface of a film of the first magnetic portion comprising the hard magnetic material is equal to or less than a critical radius Rh represented by the following formula (1):
Rh
\ue89e
36
\ue89e
AhKh
4
\ue89e
\ue89e
\u03c0
\ue89e
\ue89e
Msh
2
(
1
)
where, in the first magnetic portion comprising the hard magnetic material, Rh represents a critical radius (cm), Ah represents an exchange stiffness constant (ergcm), Kh represents a magnetic anisotropy constant (ergcc), and Msh represents saturation magnetization (emucc); and
a thickness of a cross-section in a direction parallel to a film surface of a film of the second magnetic portion comprising the soft magnetic material is twice or less of a critical radius Rs represented by the following formula (2):
Rs
=
C
\ue89e
As
Mss
(
2
)
where, in the second magnetic portion comprising the soft magnetic material, Rs represents a critical radius (cm), C represents a coefficient depending upon a shape, which is 1.44, As represents an exchange stiffness constant (ergcm), and Mss represents saturation magnetization (emucc).
8. The magnetic recording medium according to claim 4, wherein:
the magnetic region is provided such that the first magnetic portion comprising a hard magnetic material covers the periphery of the second magnetic portion comprising a soft magnetic material;
a radius of a cross-section in a direction parallel to a film surface of a film of the second magnetic portion comprising the soft magnetic material is equal to or less than a critical radius Rs represented by the following formula (2):
Rs
=
C
\ue89e
As
Mss
(
2
)
where, in the second magnetic portion comprising the soft magnetic material, Rs represents a critical radius (cm), C represents a coefficient depending upon a shape, which is 1.44, As represents an exchange stiffness constant (ergcm), and Mss represents saturation magnetization (emucc); and
a thickness of a cross-section in a direction parallel to a film surface of a film of the first magnetic portion comprising the hard magnetic material is twice or less of a critical radius Rh represented by the following formula (1):
Rh
\ue89e
36
\ue89e
AhKh
4
\ue89e
\ue89e
\u03c0
\ue89e
\ue89e
Msh
2
(
1
)
where, in the first magnetic portion comprising the hard magnetic material, Rh represents a critical radius (cm), Ah represents an exchange stiffness constant (ergcm), Kh represents a magnetic anisotropy constant (ergcc), and Msh represents saturation magnetization (emucc).
9. The magnetic recording medium according to claim 1, wherein the first magnetic portion comprising a hard magnetic material has a magnetic anisotropy easy axis in a direction perpendicular to the film surface of the magnetic recording medium.
10. The magnetic recording medium according to claim 6, wherein a difference of an average magnetic anisotropic energy density and an average saturation magnetization is caused by a difference in constituent elements constituting the first magnetic portion and the second magnetic portion.
11. The magnetic recording medium according to claim 6, wherein a difference of an average magnetic anisotropic energy density and an average saturation magnetization is caused by a difference of at least one of a composition ratio and a crystal structure of constituent elements constituting the first magnetic portion and the second magnetic portion.
12. The magnetic recording medium according to claim 6, wherein a difference of an average magnetic anisotropic energy density and an average saturation magnetization is caused by a combination of a difference in constituent elements constituting the first magnetic portion and the second magnetic portion and a difference in at least one of a composition ratio and a crystal structure of the constituent elements.
13. The magnetic recording medium according to claim 1, wherein the first magnetic portion comprising a hard magnetic material contains any of FePt, FePd, CoPt, and CoPd having an L10 regularized structure.
14. The magnetic recording medium according to claim 1, wherein the second magnetic portion comprising a soft magnetic material contains any of Fe, Ni, and Co.
15. A method of producing a magnetic recording medium comprising the steps of:
filling a plurality of holes of a porous base material with a hard magnetic material to form a first magnetic portion;
removing a part or an entirety of the porous base material to expose the first magnetic portion;
covering the exposed first magnetic portion with a soft magnetic material to form a second magnetic portion; and
filling a periphery of the second magnetic portion with a non-magnetic material to bury the first magnetic portion and the second magnetic portion in the non-magnetic material.
16. A method of producing a magnetic recording medium according to claim 15, further comprising the steps of:
filling the plurality of holes of the porous base material with first metal comprising at least one of Pt and Pd;
removing the part or the entirety of the porous base material to expose the first metal;
covering the exposed first metal with second metal containing at least one of Fe and Co;
subjecting the first metal and the second metal to heat-treatment to form the first magnetic portion comprising the hard magnetic material containing any of FePt, FePd, CoPt, and CoPd having an L10 regularized structure, and the second magnetic portion comprising the soft magnetic material containing any of Fe and Co, which covers the first magnetic portion; and
filling the periphery of the second magnetic portion with the non-magnetic material to bury the first magnetic portion and the second magnetic portion in the non-magnetic material.
17. A method of producing a magnetic recording medium comprising:
filling a plurality of holes of a porous base material with a soft magnetic material to form a second magnetic portion;
removing a part or an entirety of the porous base material to expose the second magnetic portion;
covering the exposed second magnetic portion with a hard magnetic material to form a first magnetic portion; and
filling a periphery of the first magnetic portion with a non-magnetic material to bury the first magnetic portion and the second magnetic portion in the non-magnetic material.
18. The method of producing a magnetic recording medium according to claim 17, further comprising:
filling the plurality of holes of the porous base material with second metal comprising at least one of Fe and Co;
removing one of the part and the entirety of the porous base material to expose the second metal;
covering the exposed second metal with first metal containing at least one of Pt and Pd;
subjecting the first metal and the second metal to heat-treatment to form the second magnetic portion comprising the soft magnetic material containing any of Fe and Co, and the first magnetic portion comprising the hard magnetic material containing any of FePt, FePd, CoPt, and CoPd having an L10 regularized structure, which covers the second magnetic portion; and
filling the periphery of the first magnetic portion with the non-magnetic material to bury the first magnetic portion and the second magnetic portion in the non-magnetic material.