Presentation on theme: "Elements of Metallurgy: The Physics and Chemistry of Metals by Richard Henry, P.E."— Presentation transcript:
Elements of Metallurgy: The Physics and Chemistry of Metals by Richard Henry, P.E.
Major Topics: Units Some basic physical properties: conductivity, resistivity, density, magnetic response Solids, liquids, and gasses and transitions Chemical formulas, molecules, molecular weight, radicals Balancing of chemical equations
Energy 0.102 kg x 9.81 m/s 2 = 1 Newton 0.225 pounds 1 meter 3.28 feet 1 Newton x 1 meter = 1 Joule 0.225 pounds x 3.28 feet = 0.738 foot pounds = 0.239 cal
So just how many Humvees could I lift with that cable? 9800 lb or 4440 kg, “uparmored” Take cable of one square inch cross section and 100,000 pounds/sq in strength Ans: ~10 Humvees 100 ksi = 689 MPa Pa = 1 kg m/s 2 /m 2 or 1 Newton/ m 2 (units of pressure or stress) 4400kg x 9.8 m/s 2 = 43100 Newtons, where 9.8 m/s 2 = g 1 square inch = 0.000645 square meters 1 Humvee 66,600,000 Newtons/m 2 = 66.6 MPa
Thermometer and temperature scales 273 O K 373 O K
Temperature: A measure related to the average kinetic energy of atoms or molecules. The intensity of heat. If measured in degrees Kelvin, the temperature value is directly proportionate to the average kinetic energy of the molecules in the substance. Temperature is a measure of the tendency of an object to spontaneously give up energy to its surroundings. When two objects are in thermal contact, the one that tends to spontaneously lose energy is at the higher temperature. Heat: an amount of energy possessed by a mass of molecules. Heat is accumulated as an object warms from absolute zero.
Direct Transfer of Heat Conduction Convection Radiation Cooling your computer chip….
An applied electric field superimposes a small drift velocity on the free electrons in a metal. For ordinary currents, this drift velocity is on the order of tenths of millimeters per second in contrast to the speeds of the electrons themselves which are on the order of a million meters per second. The speed of transmission of an electrical signal down a wire is on the order of the speed of light, 300 million meters per second. 40 x 10 -9 meters or about 200 atom diameters From: http://hyperphysics.phy- astr.gsu.edu/hbase/electric/ohmmic.htmlhttp://hyperphysics.phy- astr.gsu.edu/hbase/electric/ohmmic.html Electrical Conductivity
Cavendish Experiments: Cavendish exposed various metals to nitric acid. Reaction with each metal produced a colorless, odorless gas, which burned with a hot blue flame. Using pig bladders to capture the gas, Cavendish proved that water is composed of two substances, one of which represents 20% of the atmosphere. He showed that two parts by volume of the captured gas reacted with one part by volume of the gas recovered from heating the red oxide of mercury. He determined the weight of each gas, and showed the total equal to the weight of water produced. Dalton: Atomic Theory: atoms are the smallest units of an element; chemical reactions involve indivisible atoms. Henry Cavendish 1731-1810 http://en.wikipedia.org/wiki/Henry_Cavendish http://en.wikipedia.org/wiki/File:Dalton_John_desk.jpg
Equilibrium A liquid is in equilibrium with its vapor when the average rate of molecules leaving the liquid equals the rate joining.
In 1920, Stern and Gerlach sent Ag vapor through a magnetic field. The trail split in two. Ag has 47 electrons, 23 of one spin, 24 of the opposite. http://chemwiki.ucdavis.edu/Physical_Chemistry/Quantum_Mechanics/Atomic_Theory/Electrons_in_Atoms/Electron _Spin N S
Electron spin determines magnetic response http://chemwiki.ucdavis.edu/Physical_Chemistry/Quantum_Mechanics/Atomic_Theory/Electrons_in_Atoms/Elect ron_Spin