Understanding Ceramic Heating Element:
Ceramic materials that have the potential to convert electrical energy to heat energy are known as heating elements. This energy conversion occurs by a principle called Joule Heating.
The ceramic heating elements have wide applications in household appliances and industry. They are long-lasting, efficient, and sustainable at high temperatures.
Different Ceramic Materials Commonly Used as Heating Elements:
Some ceramic materials are well-suited as ceramic heating elements. The following are the most commonly used ceramic materials in the ceramic heating industry.
1.Silicon Carbide(SiC)：
Silicon carbide is the leading ceramic material used as a ceramic heating element. It is a hard compound and crystalline material which has various applications.
SiC can withstand and operate at a very high temperature up to 1973K(Kelvin). It has silicon and carbon atoms. It is a popular ceramic heating element due to high thermal conductivity, and chemical resistance.
SiC is widely used in ceramics, semiconductors, and abrasives.
Temperature Conversion Formula:
1.Kelvin to Celsius: Celsius (°C)= Kelvin (K)-273.15
2.Celsius to Kelvin: Kelvin (K) = Celsius (°C) + 273.15
Note: Zero degrees(0°C) Celsius equals 273.15 Kelvin.
2.Silicon Nitride(Si3N4):
Silicon Nitride is another common ceramic material used in heating element production. It can tolerate temperatures over 1673.15K.
It has exceptional properties like high-temperature resistance, thermal shock resistance, mechanical strength, chemical resistance, and low thermal coefficient.
Si3N4 is used in manufacturing ceramic components, semiconductors, and laboratory equipment. It also has applications in metalworking or heat treatment processes.
3.Aluminium Oxide(Al2O3):
Aluminum oxide is popularly known as alumina. It is one of the primary ceramic materials used in heating elements. It can combat 1873.15K temperatures for its high-temperature resistance.
Al2O3 also has excellent thermal conductivity, electrical insulation, and chemical resistance. It is commonly used in industrial furnaces, domestic appliances, and laboratory equipment.
4.Molybdenum Disilicide(MoSi2):
MoSi2(molybdenum disilicide) is another popular ceramic heating element. This ceramic metal has a high oxidation resistance and melting point. It can generate temperatures up to 2173K in air or oxygen.
MoSi2 can be used to generate higher temperatures depending on the design technology. It is used in high-temperature furnaces.
The ceramic component is vulnerable at room temperature.
5.Pyrolytic Boron Nitride(PBN) Ceramics：
Pyrolytic Boron Nitride(PBN) is an extremely pure ceramic material used as a heating element in the semiconductor, aerospace, laboratory equipment, and electronic industries.
PBN is a versatile ceramic component. It has high thermal conductivity, low thermal expansion, high chemical resistance, high electrical insulation, and temperature stability. PBN can generate temperatures up to 1873K.
6.Positive Thermal Coefficient Materials(PTC)
PTC is a unique ceramic material with a positive temperature coefficient. The electric resistance of PTC increases with the rise of temperature. This is exceptional because typical ceramic material has a negative temperature coefficient (NTC). Their resistance decreases with temperature increase.
The common PTC materials are semiconductor-based PTC, metal oxide varistors(MOVs), and some polymers.
They are widely used in temperature sensing, circuit protection, motor starting, self-regulated heating, and temperature-sensitive switching.
They remain stable at their materialistic state up to 1273K temperature.
7.Aluminum Nitride(AlN)
Aluminium Nitride is another exceptional ceramic material used as the heating element. It has high thermal conductivity, excellent electrical insulation, low thermal expansion, and is resistant to most chemicals.
AIN is a popular ceramic heating element used in the semiconductor industry, LED lighting, microwave components, RF, and heat sink production.
Aluminium Nitride can generate temperatures up to 873K.
Properties of a Good Ceramic Heating Element:
Almost all conductive materials create heat when electricity passes through them. However, not all ceramic materials are usable as the heating element. The ceramic materials must have some specific properties to be considered as heating elements such as:
Electrical Resistance:
Materials should have high electrical resistance to be considered heating elements. Superconductors have low resistance. They are not suitable as heating elements for their low resistance value and high conductivity.
Though the ceramic heating element should have high resistance, its resistance should not be high like the insulators. Insulators cannot pass electricity, but the heating element needs an electricity-passing character.
Oxidation Resistance:
Typically, heat accelerates the oxidation of ceramic materials. Oxidation reduces the efficiency of heating elements. It also deducts their lifespan.
An alloy is mixed with the heating elements to resist oxidation. Silicon oxide(SiO2) and aluminum oxide (AI2O3) are the common anti-oxidation materials used to create protective scales on the ceramic heating elements.
Temperature Coefficient of Resistance:
The resistances of materials change with the increase of temperature. The resistance of a conductive material increases with the temperature.
Materials possessing a high-temperature coefficient of resistance encounter a fast increase in resistivity with the temperature rise.
Good ceramic heating elements should have a low-temperature coefficient of resistance.
Mechanical Properties:
A perfect heating element must have some mechanical properties. One of the major mechanical qualities of the heating elements is ductility. Ductility allows the heating elements to draw into the wires. They are easily shaped without disturbing their tensile strength for this property.
Resistance to deformation is another must-have mechanical characteristic of ceramic heating elements. A suitable ceramic heating element can sustain its actual state at high temperatures for this mechanical resistance.
On the contrary, hard materials can be damaged at high temperatures. So they are not suitable as heating elements.
Melting Point:
The melting point is referred to the temperature at which a solid compound transforms into a liquid. The operating temperature of heating elements depends significantly on the melting point. A good ceramic heating element has a high-value of the melting point.
They can generate high temperatures without deformation due to the high melting point.
Advantages and Disadvantages of Ceramic Heating Elements:
Ceramic heating elements have some advantages and disadvantages, such as:
Advantages
- Efficiency: Ceramic heating elements are highly efficient. They can generate huge heat without changing their physical and materialistic state. They also generate more heat per watt for their high resistance value than the traditional metal elements.
- Portability: Ceramic heaters are portable for their light weight. They are ideal for warming a small office and room.
- Safety: All ceramic heaters are safe to use.
Disadvantages
- Slow Heating: Ceramic heaters take more time to reach the targeted temperature.
- Noise: Ceramic heaters are a bit more noisy than the the others.
FAQs
Which material can be used as heating element?
Silicon carbide, Silicon Nitride, Aluminium Oxide(Alumina), nickel-chromium, molybdenum-chromium-aluminum, and molybdenum disilicide are used as heating elements.
Why are ceramic heaters better?
Ceramic heaters can generate heat quickly and retain heat longer after turning off. They are highly efficient and effective for small spaces.
Conclusion: Ceramic heating elements are essential for industrial applications and household appliances. Their reliable heat generation capability makes them a valuable material for the modern heating elements industry.
Ceramic heating elements are efficient, portable, and safe to use. Further advancement in material science will elevate the ceramic heating elements to a new height.