The Car Surrounded by Ceramics in 2026: The Role of HUSCH Braking
With continuous expansion in application fields, advanced ceramic materials are becoming increasingly important throughout industrial manufacturing as structural/functional materials. In particular, progress in related technologies and the unique, well-rounded comprehensive properties of ceramics have led to their gradual widespread adoption in the automotive industry in recent years. Currently, ceramic materials are already quite common in automobiles, found in both critical functional components and key structural areas. Today, let's explore the various applications of ceramic materials in vehicles.
1. General Properties of Ceramics:
Mechanical Properties: Higher elastic modulus than metals, high hardness, high compressive strength; but brittle, low tensile strength, with very low plasticity and toughness.
Thermal Properties: High melting point, high hot strength, generally low coefficients of thermal expansion and thermal conductivity. Can maintain room-temperature performance even above 1000°C.
Electrical Properties: Generally excellent insulators. Some individual ceramics possess conductivity or magnetic permeability, falling under the category of new functional ceramic materials.
Chemical Properties: Highly stable, resistant to corrosion from acids, alkalis, salts, etc., non-aging, and (with some exceptions) oxidation-resistant.
2. Classification of Ceramic Materials:
(1) Oxide Ceramics
These are the earliest used ceramic materials, with the most varieties and the widest applications. The most commonly used include Al2O3, SiO2, MgO, ZrO2, CeO2, CaO, as well as mullite and spinel. Among these, Al2O3 and SiO2 are as widely used as steel and aluminum are in metal materials. Beyond these single oxides, there are also numerous composite oxide ceramics.
(2) Carbide Ceramics
Carbide ceramics have higher melting points than oxides, but they are prone to oxidation, which must be prevented during manufacturing and use. The most common ones include SiC, WC, B4C, TiC, etc.
(3) Nitride Ceramics
These include Si3N4, TiN, BN, AlN, etc. Among them, Si3N4 offers excellent comprehensive mechanical properties and high-temperature resistance; TiN has high hardness; BN provides wear and friction reduction properties; AlN has thermoelectric properties, and its applications are becoming increasingly widespread.
(4) Other Compound Ceramics
This refers to inorganic compounds other than the categories above, metals, and polymer materials. This includes boride ceramics (often used as ceramic additives) and chalcogenide ceramics with optical, electrical, and other special properties. Research and applications in this area are also growing.
3. Ceramic Adiabatic Engines:
Ceramic materials offer multiple advantages such as heat resistance, wear resistance, corrosion resistance, low density, and strong thermal insulation. Using them in ceramic adiabatic engines effectively prevents heat loss within the cylinders. While ceramic density is not as low as aluminum, it is considerably lower than steel. Lower density means the engine can be lighter. Combined with weight reduction from a simplified cooling system, a ceramic engine can be made lighter than a metal one. Key ceramic components include:
(1) Engine Core: To improve thermal efficiency and save energy, ceramic materials' properties (heat/wear/corrosion resistance, high elastic modulus/low expansion coefficient, low density, good insulation) are leveraged to create ceramic adiabatic engine cores. This prevents heat loss in cylinders while simplifying overall engine structure and reducing weight.
(2) Ceramic Pistons: Typically used in diesel engines, ceramic materials now replace previously used precious metals, significantly reducing costs in the manufacturing of swirl-chamber diesel engines.
(3) Ceramic Cylinder Liners: These can be implemented in several forms: the first involves coating the entire inner surface of the liner with ceramic material (exemplified by Japan's Komatsu engine); the second uses ceramic material only for the top ring section of the liner; the third involves composite manufacturing of metal and ceramic materials to create a full ceramic liner.
4. Piezoelectric Ceramics:
In recent years, as car ownership in China has surged, demands for vehicle safety and comfort have also increased. Utilizing the piezoelectric effect of piezoelectric ceramics enables functions like sensing, actuation, vibration isolation, and noise reduction in the automotive field, meeting these demands for safety and comfort.
(1) Application in Automotive Sensing: An ordinary family car is equipped with several dozen to nearly a hundred sensors, while luxury cars can have over 200. Common piezoelectric ceramic sensors include knock sensors, ultrasonic sensors, and acceleration sensors.
(2) Application in Automotive Actuation: Using the inverse piezoelectric effect, piezoelectric actuators can be made for driving power rearview mirrors, power windows, power seats, etc., in vehicles.
(3) Application in Automotive Vibration Isolation and Noise Reduction: Researchers like Toshiyuki Shibayama have designed an active mount using piezoelectric ceramics to reduce large vibrations during engine idling. The principle uses a piezoelectric ceramic to drive a large piston inside the mount; a small piston connected to it amplifies the displacement of the piezoelectric ceramic, achieving the larger displacement needed for vibration reduction at idle, effectively suppressing engine vibrations in that condition.
(4) Application in Tire Pressure Monitoring Systems (TPMS): The power generation characteristic of piezoelectric ceramics offers the possibility for a passive TPMS solution. Using the constant squeezing action during tire rotation on piezoelectric ceramics installed within the tire, based on the direct piezoelectric effect, the ceramics can continuously generate electricity, providing a constant power source for the pressure monitoring system.
5. Exhaust Treatment — Honeycomb Ceramics / Porous Ceramics:
Honeycomb ceramics are industrially used ceramics with a structure primarily consisting of numerous parallel channels in a honeycomb pattern. They can be categorized by material into cordierite, mullite, aluminum titanate, silicon carbide, zirconia, alumina, and their composites, selected based on application conditions. As an environmentally friendly material characterized by strong adsorption capacity, optimal pore structure, good thermal stability, low density, and good wear resistance, honeycomb ceramics are widely used in automotive exhaust purification fields like catalytic substrates and diesel particulate filters (DPF). With China's National VI standards requiring upgrades to exhaust treatment systems, the honeycomb ceramic market is poised for significant expansion.
6. MLCCs: Widespread Use in Automotive Electronics:
MLCCs (Multi-Layer Ceramic Capacitors) are used in automotive applications including GPS, central control systems, radio navigation, electronic stability control (ESC), and ADAS systems. Demand from these systems is substantial. The number of MLCCs required varies with the degree of vehicle electrification; a single battery electric vehicle (BEV) can require up to 18,000 MLCCs.
7. Ceramic Brake Pads:
As a new type of material, new ceramic-based friction materials can effectively enhance the safety and stability of automotive braking and are gradually being applied to brake pads. Current research on ceramic tribology, both domestically and internationally, focuses mainly on a few ceramic materials like SiC, Si3N4, Al2O3, BN, and ZrO2. Among them, C/C-SiC composites and Al2O3 ceramic friction materials are the most widely applied. Ceramic-based brake pads are popular due to their many excellent properties, particularly good corrosion resistance and durability. They are clean, environmentally friendly products with stable performance, and they do not generate significant noise during use, ensuring driving comfort.
Not long ago, Tesla announced it would offer a carbon-ceramic brake kit for its fastest production car, the Model S Plaid, in mid-2022, with the cost of the kit reaching $20,000 USD.
8. Ceramic Coatings:
Ceramic coating technology is now successfully applied in automotive and many other fields, playing an increasingly important role, with very broad prospects for technological development. For example, thermally sprayed nanostructured ceramic coatings exhibit excellent toughness, wear/ corrosion resistance, and thermal shock resistance, applicable to various mechanical components in cars such as pistons, piston rings, cylinder blocks, valve stems, hydraulic struts, bushings, pins, cams, cam followers, and turbine components.
9. Silicon Carbide (SiC) Power Devices:
In the electric vehicle field, silicon carbide serves as an important material in charging modules and power modules, offering benefits like simplifying the power supply network, increasing switching frequency, reducing component temperature rise, shrinking component size, and improving efficiency.
10. Battery Separators:
Lithium-ion batteries are the power source for electric vehicles. With technological progress, both the technology and related materials for lithium-ion batteries have developed rapidly, improving their performance and expanding their application range, especially in hybrid buses, electric vehicles, aerospace, satellites, and energy storage. As demand grows, requirements for separators, a core component, are also increasing. High-performance ceramic-coated separators are a major research direction, with high-purity alumina and boehmite being widely studied materials. Although the development direction for lithium batteries is solid-state batteries (which would eliminate the need for separators), industry estimates suggest it will take at least another decade to achieve fully solid-state batteries. Given ongoing safety incidents and the immaturity of solid-state battery technology, strengthening research on ceramic-coated separators to improve lithium battery safety remains very necessary.
11. Silicon Carbide Particle Reinforced Aluminum Matrix Composites:
These composites are particularly suitable for making wear-resistant materials like pistons and bushings. Toyota Motor Corporation has already used silicon carbide particle reinforced aluminum matrix composites for piston rings and engine connecting rods in its vehicles. Additionally, they can be used to manufacture cylinder liners, drive shafts, and other automotive parts. The prevailing trend in the automotive industry is the pursuit of energy savings, environmental friendliness, and sustainability. Therefore, for automotive components, the trend is "replacing steel with aluminum" to reduce overall vehicle weight and save energy. Thus, aluminum matrix composites have broad application prospects in the transportation sector.