Ceramic matrix composites, historical

Although few applications have so far been found for ceramic matrix composites, they have shown considerable promise for certain military applications, especially in the manufacture of armor for personnel protection and military vehicles. Historically, monolithic ("pure") ceramics such as aluminum oxide (Al203), boron carbide (B4C), silicon carbide (SiC), tungsten carbide (WC), and titanium diboride (TiB2) have been used as basic components of armor systems. Research has now shown that embedding some type of reinforcement, such as silicon boride (SiBg) or silicon carbide (SiC), can improve the mechanical properties of any of these ceramics. 

Cement A ceramic matrix composite cement is the matrix and aggregate (sand and smail pebbies, or historically pumice) is the reinforcement... 

Historically, polymer-matrix composite materials such as boron-epoxy and graphite-epoxy first found favor in applications, followed by metal-matrix materials such as boron-aluminum. Ceramic-matrix and carbon-matrix materials are still under development at this writing, but carbon-matrix materials have been applied in the relatively limited areas of reentry vehicle nosetips, rocket nozzles, and the Space Shuttle since the early 1970s. 

The main advantage of CMCs over monolithic ceramics is their superior toughness, tolerance to the presence of cracks and defects, and non-catastrophic mode of failure. It is widely accepted that in order to avoid brittle fiacture behavior in CMCs and improve the damage toloance, a weak fiber/matrix interface is needed, which serves to deflect matrix cracks and to allow subsequent fiber pullout . Historically, following the development of SiC fibers, fiber coatings such as C or BN have been employed to promote the desired composite behavior. However, the non-oxide fiber/non-oxide matrix composites generally show poor oxidation resistance , particularly at intermediate... 

Although self-reinforced UHMWPE was effectively abandoned for orthopedic bearings, interest has continued in other UHMWPE matrix composites, driven partly by new initiatives in nanocomposites materials science and polymer science. Indeed, UHMWPE matrix composites have been employed industrially for decades, and researchers have continued to explore the effect of historical standard fillers on the mechanical and dielectric properties of UHMWPE [36—40]. Solid lubricants, such as glass, graphite, ceramics (e.g., kaolin, AI2O3), and molybdenum... 

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