Electrical Properties of Technical Ceramics
Overview
Engineered ceramics exhibit superior dielectric attributes when compared to other materials, like plastics or metals. The composition of engineered ceramics makes them highly effective electric insulators, which is how they are most commonly used – though ceramics can also be carefully processed and specified for conductivity to fit the application.
Most engineered ceramics have low dielectric loss, meaning the material can maintain high levels of electromagnetic energy with very little, if any, measurable dissipation of energy.
Although polymers, rubber, and glass can be excellent electrical insulators, they do not exhibit the same mechanical, thermal, and chemical properties of technical ceramics, making ceramics ideal for high strength, high heat, or highly corrosive electronic environments.
Electrical Properties
Dielectric Loss
loss angle: δ
loss tangent: tan δ
Dielectric loss is the measurement of energy lost when a material is subjected to an electromagnetic voltage. In materials with high electrical conductivity, electrons flow freely when exposed to a charge. In an insulator, however, electrons do not flow freely. In many industrial applications, an insulator (such as technical ceramic) that can withstand high levels of exposure to electrical charges without dielectric loss is required.
Dielectric Strength
ac-kV/mm
There is only so much electrical voltage a material can withstand before it breaks down. This is quantified and measured by the material’s dielectric strength. A material with high dielectric strength can endure high voltages for longer periods of time without allowing energy through. Materials with low dielectric strength break down more quickly when exposed to electric fields. Engineered ceramics often have high dielectric strength, adding to the list of dielectric properties that make ceramics superior insulating materials for electrical applications.
Volume Resistivity
Ω-cm
Volume resistivity, also known as electrical resistivity or specific electrical resistance, is the measurement of how strongly a material can resist an electric current. A material with high volume resistivity is an electrical insulator, and a material with low or no volume resistivity designates as an electrical conductor. The inverse measurement is electrical conductivity, which is the measurement of a material’s ability to conduct an electric current instead of resisting it.
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Engineered ceramics tend to have high volume resistivity even at high temperatures, although some ceramic materials are engineered purposefully to allow some charge through (typically referred to as electrostatic discharge safe, or ESD safe ceramics), lengthening the life of the material or protecting sensitive objects it contacts.
Ceramic Materials with High Electrical Performance
Alumina:
Aluminas (aluminum oxide, Al2O3) are a commonly used technical ceramic with a range of high performance properties, including excellent dielectric behavior.
- Alumina 94%-97% demonstrates high electrical resistivity and strength and low dielectric loss.
- Alumina 99.9%-100% has exceptionally low dielectric loss.
Aluminum Nitride:
Aluminum nitrides (AlN) are used in many electronic applications due to their ability to dissipate heat quickly, unlike most electrically insulative materials, making them more efficient materials.
- Hot Pressed Aluminum Nitride has excellent dielectric strength and excellent thermal conductivity, making it ideal for ballistics armor and semiconductor applications.
- Direct Sintered Aluminum Nitride, like Hot Pressed Aluminum Nitride, has excellent dielectric strength properties, but is specified for use in applications with extreme temperature fluctuations.
Silicates:
Silicates, the oldest family of ceramics, are often used for cost-effective technical applications that require electrical resistivity, like chemical labware.
- Steatite has low dielectric loss combined with high dielectric strength – and is inexpensive to manufacture.
- Mullite has excellent thermal shock properties and dielectric strength.
Silicon Carbide (SiC):
CoorsTek has carefully tailored the manufacturing process of silicon carbides for specific volume resistivity.
- Reaction Bonded Silicon Carbide, sometimes called siliconized silicon carbide, is a silicon metal infiltrated ceramic with customizable properties, depending on the use case.
Specialty Ceramics:
The CoorsTek portfolio includes a variety of specialty ceramics, manufactured for unique, specific applications. Several of these specialty materials have excellent dielectric behavior.
- Titanate formulations were manufactured specifically for use as a dielectric resonator in antennas.
- ESD-Safe Ceramics were developed to protect sensitive microelectronic components from static electricity buildup by slowly dissipating the accumulated charge to prevent rapid discharge or arcing.
- Carbon and graphite, unlike the other ceramic materials on this list, make excellent electrical conductors.
Applications Requiring Optimal Electrical Properties
Ready to get started? Contact the CoorsTek engineering team today to begin your manufacturing project or to discuss customizing a ceramic material for your specific application.
CoorsTek technical ceramics expertise allows our engineers to work directly with our customers on custom specifications and designs for a wide range of applications. Engineered ceramic materials with good electrical properties are highly valuable in today’s industrial environment, in which manufacturing innovations push materials beyond their limits.
CoorsTek ceramics are frequently used in the following industries and applications:
Aerospace & Defense
With a stable dielectric constant and low electrical loss, technical ceramics are ideal for use in GPS antenna components. Ceramic GPS antenna components provide accurate tuning for a multitude of mobile communications devices used in defense, aerospace, and automobile applications.
Cerbec® Silicon Nitride Bearing Balls
Used in multiple industries from automotive to renewable energy to dentistry, CoorsTek Cerbec Silicon Nitride balls offer extraordinary performance in critical duty applications requiring mechanical strength as well as electrical resistivity. Learn More
Automotive & Transportation
Carbon brushes provide electrical current to rotate small motors by connecting the coils of the rotor to complete the electric circuit, and are used widely in automobile doors, windows, and locks. Minute changes to material properties can greatly affect the performance of each brush. Our brushes are made with high-purity graphite (often mixed with copper) to provide tightly controlled electrical conductivity.
Thick- and Thin-film ceramic substrates, are ideal for power electronic and automotive applications such as engine circuitry components and LED lighting. With excellent electrical insulation and other thermal and mechanical properties, ceramic substrates are ideal for usage in LED lighting and sensor applications for automobiles.
Ceramic heat exchangers, aka “cooling boxes” transfer heat from power electronics to the water cooling systems used in power converters in local and metro rail vehicles. These long life, efficient systems are manufactured from aluminum nitride, a unique ceramic material which provides excellent electrical insulation in combination with high thermal conductivity.
Energy: Power & Utilities
Electrically insulating ceramics are the core components of vacuum interrupters, switches used in medium and high-voltage circuit breakers for power and utility applications.
As a vertically integrated, full-service manufacturer, CoorsTek manufactures vacuum interrupters using electrically insulative alumina, which is then bonded to form a high-strength metal-to-ceramic joint.
Semiconductor
Technical ceramics show their mettle in demanding semiconductor fabrication applications. Materials such as ultra-high purity aluminas are ideal for parts for plasma etch equipment like nozzles and focus rings requiring exceptional dielectric strength.
Medical
High purity technical ceramics provide superior strength and biocompatibility for use in medical applications where specific electrical properties are necessary. CoorsTek CeraPure™ medical ceramics offer low dielectric loss (electrical insulation) and RF transparency for electro-implantable devices.