Wear Of Ceramics And Polymers

Ceramic fibers in cmcs can have a polycrystalline structure as in conventional ceramics.

Wear of ceramics and polymers.

Ceramics are hard and strong but brittle. For this reason polymers are very elastic e g a rubber band can be easily melted and have low strength. Different materials have different properties. The distortion phenomenon under load in ceramics is also reasonably small as compare to metals.

Ceramic balls are also manufactured to substitute steel in ball bearings. Compare metals polymers and ceramics on a chart or table using the following properties and the ratings low high and highest. Grit size effects in two and three body abrasive wear are observed for ceramics. In bearing and wear applications polymers provide extensive advantages over metals by allowing for lower power motors for moving parts due to lower frictional properties of polymer wear components compared to metals.

In polymers there are covalent bonds between the atoms of the polymer but the polymeric macromolecules or chains are kept together by van der waals forces. Of all the four types of bonds van der waals is the weakest. The higher hardness of ceramics explicates that these are slighter disposed to wear out and can be more durable that steel ball bearings. They can also be amorphous or have inhomogeneous chemical composition which develops upon pyrolysis of organic precursors the high process temperatures required for making cmcs preclude the use of organic metallic or glass fibers only fibers stable at temperatures above 1 000 c 1 800 f can be used.

These changes may be undesirable such as changes during use or desirable as in biodegradation or deliberately lowering. They also provide excellent electrical insulation properties. Polymers are strong and tough and often flexible. The lower wear rates allow for less maintenance related downtime.

Both free energy of oxide formation and the d valence bond character of metals are related to the friction and wear characteristics for metals in contact with ceramics. Density ductility hardness corrosion resistance hardness thermal conductivity electrical conductivity wear resistance. Both friction and wear of ceramics are anisotropic and relate to crystal structure as with metals. Composite materials combine two or more materials.

The low frictional properties provide for less wear as well.