1. A method for making armor plate resistant to armor piercing small arms ammunition, the method comprising:
providing a steel plate having a thickness and a nominal chemical composition in weight percent of 0.38-0.44 C, 1.65-2.00 Ni, 0.65-0.90 Cr, 0.20-0.30 Mo, 0.15-0.35 Si, 0.60-0.85 Mn, P less than or equal to 0.035, S less than or equal to 0.05, balance Fe and other incidental impurities;
carburizing one side of the steel plate to produce a carburized plate having a carburized side and a non-carburized side, the carburized side of the steel plate having a carbon concentration of at least 0.9 percent by weight and the non-carburized side having a carbon concentration of between 0.38 and 0.45 percent by weight, and
heating the carburized plate at a temperature range between 1225 and 1275 degrees Fahrenheit for a time between 15 to 45 minutes and thereafter heating the carburized plate at a temperature range between 1525 and 1575 degrees Fahrenheit for a time between 10 and 30 minutes.
2. The method of claim 1, further comprising the step of thermal processing the carburized steel plate such that the carburized side has a hardness of at least 58 Rockwell hardness C and the non-carburized side has a hardness >=53 and <=55 Rockwell hardness C.
3. The method of claim 1, wherein the carburizing includes gas carburizing.
4. The method of claim 3, wherein a gas used in the gas carburizing has a carbon potential between 0.7 and 1.0.
5. The method of claim 4, wherein the gas carburizing includes heating the steel plate to an elevated temperature, the elevated temperature being between 1600 and 1800 degrees Fahrenheit.
6. The method of claim 5, wherein the elevated temperature is between 1650 and 1750 degrees Fahrenheit.
7. The method of claim 5, wherein the steel plate is heated at the elevated temperature for a time between 6 and 18 hours.
8. The method of claim 5, wherein the steel plate is heated at the elevated temperature for a time between 10 and 14 hours.
9. The method of claim 1 further comprising:
subsequent to said step of heating, quenching the carburized plate in molten salt to a temperature range between 325 and 375 degrees Fahrenheit for a time between 1 and 10 minutes; and
removing the carburized plate from the molten salt and allowing it to air cool to room temperature;
reheating the carburized plate at a temperature range between 350 and 400 degrees Fahrenheit for a time between 1 and 3 hours; and
air cooling the carburized plate to room temperature.
10. The method of claim 1, wherein the carburizing includes gas carburizing.
11. The method of claim 10, wherein a gas used in the gas carburizing has a carbon potential between 0.7 and 1.0.
12. The method of claim 11, wherein the elevated temperature is between 1650 and 1750 degrees Fahrenheit.
13. The method of claim 12, wherein the steel plate is heated at the elevated temperature for a time between 10 and 14 hours.
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. An aquarium comprising:
a plurality of exterior walls that define a tank;
a cylindrical wall within said tank that defines a cylindrical viewing area;
a first upright interior wall adjacent said cylindrical wall that defines a water inlet chamber between said cylindrical wall and the one of said exterior walls;
a spillover riser in said water inlet chamber; and
a water inlet in communication with one side of said spillover barrier
2. An aquarium according to claim 1 wherein said water inlet is positioned in lower portions of said water inlet chamber.
3. An aquarium according to claim 1 further comprising biological filtration media in said inlet chamber.
4. An aquarium according to claim 3 further comprising chemical filtration media in said inlet chamber.
5. An aquarium according to claim 4 further comprising a media screen in said inlet chamber that separates said inlet chamber into a portion of biological filtration media and a portion of chemical filtration media.
6. An aquarium according to claim 1 and further comprising:
a second upright interior wall adjacent said cylindrical wall and opposite said first upright wall that defines an air inlet chamber between said cylindrical wall and a different exterior wall;
an air inlet positioned in lower portions of said air inlet chamber;
a spillover riser in said air inlet chamber; and
a water outlet in communication with said air inlet chamber on the opposite side of said air inlet spillover riser from said air inlet.
7. An aquarium according to claim 1 wherein portions of said cylindrical wall are perforated to permit water to flow between said cylindrical viewing area and the remainder of said tank.
8. An aquarium according to claim 6 further comprising an overflow barrier between said cylindrical wall and said first upright interior wall
9. An aquarium according to claim 6 wherein said water outlet is positioned in lower portions of said air intake chamber.
10. An aquarium according to claim 6 further comprising a foam collection cup that rests at the top of said air inlet chamber.
11. An aquarium according to claim 1 wherein at least one of said exterior walls is formed of a transparent polymer.
12. An aquarium according to claim 11 wherein all of said walls are formed of a transparent polymer.
13. An aquarium according to claim 1 wherein said water inlet chamber includes a vertical tube.
14. A method of cultivating live jellyfish comprising:
circulating water through a biological medium in the aquarium;
then into a cylindrical viewing area in the aquarium;
then from the cylindrical viewing area to an air inlet in the aquarium but outside of the viewing area;
then propelling the water upwardly in the aquarium with air from the air inlet; and
then separating the air from the water by directing the water downwardly over a riser in the aquarium.
15. A method of cultivating live jellyfish according to claim 14 and further comprising:
circulating water through a chemical medium in the aquarium after the step of circulating water through a first biological medium in the aquarium; and
thereafter circulating water through a second biological medium in the aquarium.
16. A method of cultivating live jellyfish according to claim 14 and further comprising:
circulating the water through a plurality of deflectors into the cylindrical viewing area in the aquarium; and
then returning the water from the cylindrical viewing area to the air inlet in the aquarium.
17. A method of cultivating live jellyfish according to claim 14 further comprising directing the water from the aquarium to a chiller to maintain a desired temperature.
18. A method according to claim 17 further comprising directing the water from the chiller to the first biological medium.
19. A method according to any of claim 14 comprising circulating salt water.
20. A method according to any of claim 14 comprising circulating the water with jellyfish in the aquarium.