25-08-2017, 09:32 PM
DISC BRAKES
DISC BRAKES SEMINAR REPORTS.docx (Size: 25.91 KB / Downloads: 39)
The disc brake is a device for slowing or stopping the rotation of a wheel while it is in motion.
A brake disc is usually made of cast iron, but may in some cases be made of composites such as reinforced carbon- carbon or ceramic matrix composites. This is connected to the wheel and/or the axle. To stop the wheel, friction material in the form of brake pads is forced mechanically, hydraulically, pneumatically or electromagnetically against both sides of the disc. Friction causes the disc and attached wheel to slow or stop. Brakes convert motion to heat, and if the brakes get too hot, they become less effective, a phenomenon known as brake fade.
Properties:
The thermal and electrical properties of the composite are a result of its constituents, namely fibers, matrix and pores as well as their composition. The orientation of the fibers yields anisotropic data. Oxide CMCs are very good electrical insulators, and because of their high porosity their thermal insulation is much better than that of conventional oxide ceramics.
Advantages:
CMC materials overcome the major disadvantages of conventional technical ceramics, namely brittle failure and low fracture toughness, and limited thermal shock resistance. Therefore, their applications are in fields requiring reliability at high-temperatures and resistance to corrosion and wear. These include:
1. Heat shield systems for space vehicles, which are needed during the re-entry phase, where high temperatures, thermal shock conditions and heavy vibration loads take place.
2. Components for high-temperature gas turbines such as combustion chambers, stator vanes.
3. Components for burners, flame holders, and hot gas ducts.
4.Brake disks and brake system components, which experience extreme thermal shock.
5. Components for slide bearings under heavy loads requiring high corrosion and wear resistance.
In addition to the foregoing, CMCs can be used in applications, which employ conventional ceramics or in which metal components have limited lifetimes due to corrosion or high temperatures.