BRONZE

By Qingda Hu

Information on the spouting bowl

• It works due to constructive interference of waves in the water – they are called Faraday waves (non-linear standing waves)

• When the waves break the surface of the water, it “jumps” or spouts

• The initial vibration comes from hands rubbing the handles

• The resonance pitch of the bowl depends on the size of the bowl

• The bowl is constructed from bronze

Composition of Bronze

• Bronze is a metal alloy

• It is composed of mainly copper with tin

• The bronze of the bowl is most likely bell bronze

• Bell bronze, usually used to make bells, resonates very well

• It is 20% tin and 80% copper

Copper

• SYMBOL Cu

• ATOMIC NUMBER 29

• ATOMIC MASS 63.55

• FAMILY Group 11 (IB) [Ar]3d94s1

Tin

• SYMBOL Sn

• ATOMIC NUMBER 50

• ATOMIC MASS 118.69

• FAMILY Group 14 (IVA) Carbon

[Kr]4d105s25p2

Structure of Bronze

• Bronze has a face centered cubic crystal lattice (refer to model)

• The angles are different depending on the temperature and amount of tin in the bronze (refer to graph on next slide)

• The different size of the tin atoms compared to copper atoms changes the FCC structure and gives bronze many of its properties

• The bonds are metallic bonds

Face-center-cubic

Properties of Bronze (structurally)

• The strength of bronze and its elasticity makes it good for resonating. The waves traveling through the bronze are not absorbed. Compared to a bowl made from plastic or wood.

• Its crystal structure makes its surface more slippery. This allows the hand to slip when gliding over the handles, creating vibrations. This also means that bronze is more resistant to wear

• The close packing of bronze giving it a density slightly higher than iron. Its density allows it to pass on its vibrations to the water effectively.

Properties of Bronze (other)

• The copper in the bronze makes it antiseptic, this kills the bacteria in the water.

• The metal is resistant to corrosion, because of the patina layer which forms when it reacts with oxygen. Compared to a bowl made from iron, it would last longer.

• Its melting point is 800-1000 degrees Celsius. This is less than iron (1811k) or pure copper, which means its easier to shape.

Abstract/summaryThe Chinese or spouting bowl which is used as a training tool for the

science school students is made from bronze. It is possibly an artifact from China or a replica. This means the material was chosen not only for its structure importance, but also its historical accuracy. Bronze is a alloy of copper and tin (Nielsen, 2010). Depending on the amount of tin is added to the copper, bronze has slightly different phases. All these phases have a face-centered-cubic motif, but with the tin atoms replacing the copper ones in different places (Nielsen, 2010). The bronze age came after the copper age. Bronze is stronger than copper and even iron at the time (Tin, 2007). The copper in the bronze forms a layer of patina when it reacts with oxygen, which protects the inside. Unlike iron which forms a non-protective layer of rust. This makes bronze a better choice for making a bowl which holds water. Bronze is slightly more dense than iron. This allows bronze to pass on its vibrations to the water, as a light material like plastic or aluminum might not be able to create large enough waves. Bell bronze is use to make many instruments, this is due to its ability to resonate. This ability is also important when making a spouting bowl.

Bibliography

• Nielsen, W. D. (2010). Metallurgy of copper-base alloys. Copper development association. Retrieved from http://www.copper.org/resources/properties/703_5/703_5.html

• Spouting bowls. (2010). Acme klein bottle. Retrieved from http://www.kleinbottle.com/SpoutingBowls.htm

• Tin. (2007). Chemistry explained. Retrieved from http://www.chemistryexplained.com/elements/T-Z/Tin.html

• Viñals, J. (2007). Faraday waves. Jorge Vinals: department of physics, McGill University. Retrieved from http://www.physics.mcgill.ca/~vinals/research/fwaves/index.html

Picture references

• http://www.kleinbottle.com/images/Spouting%20Bowl%20Med%20dry%2034.jpg

• http://objectsandelements.com/shop/images/sheet%20rich%20low%20and%20brass.jpg

• http://www.webelements.com/_media/elements/kossel_diagrams/Sn.jpg

• http://ocw.weber.edu/automotive-technology/ausv-1320-automotive-electronics/images/copperatom

• http://www.georgesbasement.com/Microstructures/NonFerrousAlloys/Lesson-1/Slide15.jpg

• http://www.copper.org/resources/properties/703_5/images/FIG_1.JPG

• http://ecee.colorado.edu/~bart/book/fcc.gif