Shell of pressure-resistant container, pressure-resistant container, and exploratory apparatus
There are provided a shell of a pressure-resistant container that is made of ceramics, is used for a pressure-resistant container formed with a through hole, and can be made higher in strength and lighter in weight, as well as to provide a pressure-resistant container and an exploratory apparatus. A shell of a pressure-resistant container includes a shell portion and a thick-walled portion. The shell portion is made of ceramics and has a convexly-curved surface. The thick-walled portion is made of ceramics, continues into the shell portion, is larger in thickness than the shell portion, and has a through hole penetrating through the thick-walled portion in a thickness direction thereof.
1. A shell of a pressure-resistant container, comprising:
a shell portion which has a curved shape and is made only of ceramics and has a convexly-curved surface; and
a thick-walled portion which has a curved shape and is made only of ceramics, continues into the shell portion, is larger in thickness than the shell portion, and has a through hole penetrating through the thick-walled portion in a thickness direction thereof, the thick-walled portion being defined in part by an imaginary spherical surface,
wherein the shell portion includes a shell-portion inner surface defined by part of an imaginary spherical surface having a first radius of predetermined length, and a shell-portion outer surface defined by part of an imaginary spherical surface having a second radius which is longer than the first radius, and
the thick-walled portion includes a thick-walled-portion inner surface defined by part of an imaginary spherical surface having a third radius which is shorter than the first radius, and a thick-walled-portion outer surface defined by part of an imaginary spherical surface having a fourth radius which is longer than the second radius, and an angle, which is formed between straight lines connecting a center point of a half sphere with points of the thick-walled portion where a thickness of the thick-walled portion begins to decrease toward the shell portion, that is in a range of 20° to 30°.
2. The shell of a pressure-resistant container according to claim 1 , wherein the following formulae are satisfied:
t 2=3.8× t 1−3.9( t 1≧1.16) (1), and
1.66≦ t 1+ t 2≦4.8 (2),
wherein T represents a thickness of the shell portion; T 1 represents a radial distance between an imaginary spherical surface having a fifth radius which is equal to an average of the first radius and the second radius, and the thick-walled-portion inner surface; T 2 represents a radial distance between the imaginary spherical surface having the fifth radius and the thick-walled-portion outer surface; t 1 represents a ratio of T 1 to T; and t 2 represents a ratio of T 2 to T.
3. The shell of a pressure-resistant container according to claim 1 , wherein the shell portion and the thick-walled portion are made of silicon nitride sintered compact having a relative density of 98% or more.
4. The shell of a pressure-resistant container according to claim 1 , wherein the shell portion and the thick-walled portion are made of alumina sintered compact having a hardness of 15 GPa or more.
5. A pressure-resistant container, comprising:
the shell of a pressure-resistant container according to claim 1 .
6. An exploratory apparatus, comprising:
the pressure-resistant container according to claim 5 .