Engineering materials nonmetals

Maintaining a safe and healthy workplace is more complex than it has ever been. New materials and new processes have created new problems. About 8,000 new chemical compounds are created each year. Production materials have become increasingly complex and exotic. Engineering materials now include carbon steels, stainless steels, cast irons, tungsten, molybdenum, titanium, aluminum, powdered metals, plastics, etc. Each of these metals requires its own specialized processes and has its own associated hazards. Nonmetals are more numerous and have also become more complex. Plastics, plastic alloys, and blends, advanced composites, fibrous materials, elastomers, and ceramics also bring their own potential hazards to the workplace. 

Figure 13-2, the insulators are colored red. Common insulators include wood, plastic, and rubber. Most materials that are nonmetals are also insulators. Engineers use insulators to stop the flow of electrons. 

Located on the periodic table of the elements in Figure 13-2 is an area between the conductors and insulators, or metals and nonmetals, and are the elements called semiconductors. This area is colored blue. Semiconductors typically contain four electrons in their outer orbit. Materials that are semiconductors include silicon and germanium. As shown in Figure 13-7, the silicon atom has four electrons in its outer orbit. By adding or subtracting electrons, engineers can modify semiconductors to perform a desired operation. 

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