How Do Ceramic Matrix Composites Hold Up to Temperature Extremes?
Temperature exposure is always a concern when choosing composite materials. The temperature extremes a part will be exposed to impact a manufacturer’s choice of materials. Enter ceramic matrix composites (CMCs). They exhibit exceptional performance under extreme temperature conditions.
CMCs are considered advanced materials within the composites industry. They are manufactured by combining ceramic fibers with a specially formulated ceramic matrix. Matrices are typically made from substances like silicon carbide and alumina. Meanwhile, reinforcing fibers can be anything from carbon to mullite.
CMCs and Mechanical Strength
Mechanical strength is a big advantage that comes with choosing ceramic matrix composites. Few composites are as strong as CMCs. And unlike other composites, CMCs maintain a significant portion of their mechanical strength at high temperatures.
Limited mechanical loss makes CMCs ideal for load bearing applications. Even in very hot conditions, they can continue bearing heavy loads virtually unscathed.
Excellent Temperature Resistance
One of the reasons CMCs maintain mechanical strength in high temperatures is their exceptional heat resistance. A typical CMC can maintain its structural integrity even at temperatures in excess of 1,000°C. It is not unheard of for a CMC to manage temperatures as high as 1,800°C.
This kind of heat resistance is important in the aerospace industry. Spacecraft, in particular, are exposed to unimaginable temperatures during flight and atmospheric re-entry. More traditional materials could never withstand the heat.
Creep and Thermal Expansion
Extreme temperatures can lead to creep and thermal expansion. Once again, CMCs are exceptionally resistant. Because CMCs resist high temperatures, they are less prone to both creep and thermal expansion.
If you are not familiar with creep, it is understood as a progressive deformation of a composite material over time. Creep is commonly caused by load stress or exposure to high temperatures. It can ultimately lead to catastrophic failure.
As for thermal expansion, the lower the better. A lower coefficient of thermal expansion dictates that a part will retain its stability even as temperatures change in either direction. CMCs demonstrate lower coefficients than other types of materials. That makes them better able to resist thermal expansion.
CMCs Can Be Customized for Temperature
CMC temperature resistance is further enhanced through customization. In other words, ceramic matrix composites can be tailored to need. They can be engineered to withstand the known stresses, temperatures, and environmental conditions unique to each application.
The ability to tailor CMCs to individual applications gives manufacturers a lot more flexibility – especially on highly sensitive applications with very tight tolerances. Aerospace applications immediately come to mind.
Reduced Cooling Requirements
The proverbial icing on the cake is that CMCs demonstrate reduced cooling requirements. Because they can operate at higher temperatures while maintaining strength and stability, they do not have to be cooled as much or as frequently as other types of composites.
Reducing a composite’s cooling needs gives engineers the opportunity to utilize precious resources for other things. And in some cases, the need to cool a composite is eliminated completely. That makes for more efficient systems overall.
Success Where Others Fail
The bottom line for ceramic matrix composites is that they hold up exceptionally well to extreme temperatures. That makes them ideal for jet engines, rocket nozzles, gas turbines, and other applications prone to high heat.
With CMCs, you get tremendous heat resistance along with reliable mechanical strength and dimensional stability. Best of all, our industry has not even come close to tapping out CMC potential. There is still plenty of room to improve what many consider the top-of-the-line composite. And don’t forget, Axiom is one of the few companies that source CMCs.