Mathematics and Science in Schools in Sub-Saharan Africa

MATERIAL SCIENCE CORROSION

The degradation of a material due to a reaction with its environment. Corrosion The degradation of a material due to a reaction with its environment.

Environmental Factors

This process is called oxidation. Corrosion Most metals are oxidized by the oxygen in air. This process is called oxidation.

Electrons leap from the metal to the oxygen molecules. Oxidization Electrons leap from the metal to the oxygen molecules.

Oxidization Leo the lion says “ger”

Lab: Oxidation & Reduction of Copper For this lab you will need copper filings, zinc powder, HCl solution, a test tube and a burner.

Lab: Oxidation & Reduction of Copper Data Chart Copper Before Heating Copper After Heating Copper After Adding HCl Copper After Adding Zinc Students place a small amount of copper into their test tube. They record their observations of the appearance of the copper. Students then heat up the copper in the test tube until all the copper color is gone. The copper oxide formed should be one solid piece of material. Students record their observations of the appearance of the copper oxide. Students add HCl solution to the test tube. Students record their observations of the appearance of the substance in the test tube. Students then add some zinc to the solution. They should see the copper replaced and isolated. Students record their observations of the appearance of the copper.

Corrosion Chemistry The negative oxygen ions which are thus formed penetrate into the metal, causing the growth of an oxide surface.

Corrosion Chemistry As the oxide layer grows the rate of electron transfer decreases. The corrosion stops and the metal is made passive.

Corrosion Can Be a Good Thing! Energy production by batteries rely on metal corrosion.

Hurricanes, floods, tornadoes and earthquakes total, on average, 17 billion each year.

$276 Billion In the U.S., financial losses due to corrision can top $276 billion dollars a year!

Cost of Corrosion in 1998 GNP

The Silver Bridge-1967 The General Corporation and the American Bridge Company constructed the Highway Bridge in 1928. It was designed as a two-lane eye-bar suspension type bridge, measuring 2,235 feet in total length, including the approaches. The bridge was designed under the specifications set forth by the American Society of Civil Engineers. The bridge was dubbed the 'Silver Bridge' because it was the country's first aluminum painted bridge. The bridge was dubbed the 'Silver Bridge' because it was the country's first aluminum painted bridge.

The Silver Bridge-1968 On December 15,1967 at approximately 5 p.m., the U.S. Highway 35 bridge connecting Point Pleasant, West Virginia and Kanauga, Ohio suddenly collapsed into the Ohio River. At the time of failure, thirty- seven vehicles were crossing the bridge span, and thirty-one of those automobiles fell with the bridge. Forty- six individuals perished with the buckling of the bridge and nine were seriously injured. Along with the numerous fatalities and injuries, a major transportation route connecting West Virginia and Ohio was destroyed, disrupting the lives of many and striking fear across the nation. Along with fatalities and injuries, a major transportation route connecting West Virginia and Ohio was destroyed striking fear across the nation.

Rebar Corrosion

Rebar Corrosion Concrete damage due to rebar corrosion is a common problem among bridges and other saltwater structures.

Bridge Corrosion According to a 1997 report, of the 581,862 bridges in and off the U.S.A. federal-aid system, about 101,518 bridges were rated as structurally deficient. Most of these bridges were not in danger of collapse, but they were likely to be load posted so that overweight trucks will be required to take a longer alternative route. According to a 1997 report, of the 581,862 bridges in the U.S.A. about 101,518 bridges were rated as structurally deficient.

(Lowes Motor Speedway) 15% of almost 600,000 bridges in the USA are structurally deficient because of corrosion.

Infrastructure Repair The estimated cost is ~$78 billion, and it could increase to as much as $112 billion, depending on the number of years it takes to meet the objective.

The BP pipeline at Prudhoe Bay. Prudhoe Bay is the nation's largest oil field.

BP had to shut down production.

A section of pipeline shows corrosion. The pipe walls had thinned in 12 areas of the pipeline.

Closing the pipeline will cut U.S. production by 400,000 barrels daily.

Corrosion of Electronics Corrosion in electronic components manifests itself in several ways. Computers, integrated circuits, and microchips are now an integral part of all technology-intensive industry products, ranging from aerospace and automotive to medical equipment and consumer products, and are therefore exposed to a variety of environmental conditions. Corrosion in electronic components are insidious and can not be readily detected. Therefore, when corrosion failure occurs, it is often dismissed as just a failure and the part or component is replaced. Because of the difficulty to detect and identify corrosion failures, the cost of corrosion is difficult to determine.

Erosion Corrosion

Prevention

Material Selection Stainless Steel

Material Selection This large statue by Pablo Picasso in front of the Chicago city hall is made of weathering steel that does not need painting in many boldly exposed environments.

The most corrosive resistant element. Iridium The most corrosive resistant element.

Barrier Protection

Protective Organic Coatings

Rebar Protection

Protective Metal Coatings Protective coatings can be metallic, such as the galvanized steel shown below, or they can be applied as a liquid “paint.” Most of the research and testing of protective coatings at the Kennedy Space Center is related to paint-like protective coatings.

This process is called cathode protection. The rate of corrosion reactions may be controlled by passing anodic or cathodic currents into the metal. This process is called cathode protection.

This technology can provide a long-term solution to corrosion issues for both steel and steel reinforced concrete structures and concrete highway pavement subjected to premature failure as a result of exposure to marine or deicing salts.

Cathode Protection

Cathode Protection This can only be applied if there is a suitable conducting medium such as earth or water through which a current can flow to the metal to be protected.

Sacrificial Protection

Reactivity Sodium & Water

Examples

Lab: Activity Series Activity Series Lab is available through Flynn Scientific! Catalog number #AP59140-$68.65.

A team from the University of Minnesota, University of Southern California, Woods Hole Oceanographic Institution and Lawrence Berkeley National Laboratory took samples from the East Pacific Rise, a volcanic mid-ocean ridge.

Iron trapped in this way does not rust. They found that organic compounds capture some iron from hydrothermal vents, enabling it to be carried away in seawater. Iron trapped in this way does not rust.

For the scientists, discovering shiny iron in the ocean was like fishing a dry sponge out of a pool. Iron is the limiting nutrient in most parts of the oceans, meaning that its scarcity is the only thing standing in the way of faster growth.