Advanced ceramics a small step, a big step in the automotive industry (ceramic sintering furnace)

A generation of materials, a generation of industry. In the automotive industry, materials are everything, and the innovation of materials often promotes the development of the automotive industry. Nowadays, with the continuous development of the automobile industry and people's requirements for automobile environmental protection, energy saving, safety and comfort are getting higher and higher, automobile materials are constantly changing.
For example, the cars of decades ago were almost all made of steel. Only a few of these parts are made of plastic or wood. However, nowadays, the automotive industry has made great changes in the application of materials. Lightweight new materials such as aluminum are popular, and various synthetic materials are emerging in endlessly. Lighter and stronger materials have come out one after another, which is bound to be the car's"The Iron Age" ends.
Advanced ceramic and metal materials, polymer materials and calledThe "three solid materials" have excellent mechanical, acoustic, optical, thermal, electrical, biological and other characteristics, and have important applications in the automotive industry. Especially in today's electric wave, the system design of automobiles has undergone earth-shaking changes, and major assemblies and parts are also undergoing simultaneous changes. A small step in advanced ceramics may lead the automotive industry to take a big step forward. For example, silicon nitride ceramic substrates have promoted the acceleration of the third generation of semiconductors on the car, and the application of silicon nitride ceramic bearings has directly broken through the limitations of durability, high speed and electrical corrosion.

Traditional fuel car era

Engine

Ceramic materials have the advantages of heat resistance, wear resistance, corrosion resistance, low density, and strong heat insulation. The use of ceramic materials in the preparation of ceramic heat-insulated engines will well prevent the loss of heat energy inside the cylinder. Although the density of ceramics is not as low as that of aluminum, it is much lower than that of steel. The lower density means that the engine can reduce weight. Combined with the weight reduced by the simplification of the heat dissipation system, the weight of ceramic engines can be made lighter than metal engines. The main ceramic parts are the following.

1. Engine heart

In order to improve the thermal efficiency of the engine and save energy, the heat resistance, wear resistance, corrosion resistance and high elastic modulus of ceramic materials can be used.(Low expansion coefficient), low density, good heat insulation and other characteristics to make ceramic heat insulation engine core, which can not only prevent heat loss in the cylinder, but also simplify the overall structure of the engine and reduce the weight of the engine.

 

Photo Source:Pexels

2. Piston ring

 

The piston ring is a device that prevents gas from leaking from the combustion chamber to the crankcase. Traditional piston rings are usually made of cast iron or steel materials, but due to high temperature and high-speed rotating environment, these materials are prone to wear and deformation. Therefore, some automobile manufacturers began to use high-performance ceramic materials to make piston rings to improve their wear resistance and high temperature resistance.

 

3. Ceramic cylinder liner

 

Ceramic cylinder liners can be divided into the following forms: the first is that the inner surface of the cylinder liner is completely covered by ceramic material, and the Japanese Komatsu engine is a typical example; the second is only used in the preparation of the upper ring of the cylinder liner. Material; and the third is to prepare metal and ceramic materials to make a full ceramic cylinder liner.

 

4. Ceramic gas distribution mechanism

 

Using the characteristics of low density, heat resistance and wear resistance of ceramic materials, the valve, valve seat, tappet, valve spring and rocker arm are made of ceramic materials, which can reduce the deformation of the valve seat and the bounce when seated, reduce noise and vibration, and extend Service life.

 

ceramic sensor

 

In modern cars, electronic components account for an average of the cost of parts per premium car.At a rate of 30%, there are as many as hundreds to hundreds of automotive sensors. Advanced sensors that used to be installed on luxury, high-end cars or special vehicles are now also settled in mid-and low-end cars.
Ceramic sensor materials used in automobiles include thermal-sensitive ceramics, gas-sensitive ceramics, piezoelectric ceramics, humidity-sensitive ceramics and thick-film force-sensitive ceramics.

 

Tail gas treatment-Honeycomb ceramics

 

Under the background of "double carbon", China has formulated a series of motor vehicle pollutant emission regulations, the control standards have been continuously improved, the technical route of exhaust gas treatment has been continuously upgraded, and the technical specifications of products have been continuously improved. In July 2021, the National VI standard, which can be called the world's most stringent emission standard, was officially implemented. Half a year after the implementation of the National VI, my country issued the "14th Five-Year Plan" Comprehensive Work Plan for Energy Conservation and Emission Reduction, proposing to fully implement the National VI for Automobiles Emission Standards and National IV emission standards for non-road mobile diesel machinery will basically eliminate National III and below emission standard vehicles.

 

 

Honeycomb ceramic carrier is a kind of ceramic carrier with high mesh, large specific surface area, high compressive strength, low thermal expansion coefficient and excellent thermal shock resistance. Cordierite and silicon carbide materials are commonly used in catalytic converters for vehicle exhaust purification treatment, which catalytically convert harmful gases in vehicle exhaust gas and filter and intercept solid particles to meet increasingly stringent emission regulations.

ceramic coating

At present, ceramic coating technology has been successfully applied in automobile and many other fields, playing an increasingly important role, and its technology development has a very broad prospect. For example, thermal spraying nanostructured ceramic coatings have excellent toughness, wear resistance, corrosion resistance and thermal shock resistance, and can be applied to various mechanical parts of automobiles. Such as pistons, piston rings, cylinder blocks, valve stems, hydraulic struts, bearings, pins, cams, lobes, turbine components, etc.

 

In addition to the above, the components made of special ceramic materials in traditional automobiles include ceramic heaters made of ceramic insulation, rotors made of ceramic high temperature and high strength, converters, heat exchangers, heating element joints and Turbine chargers and turbine impellers on gas turbines.

 

New energy vehicle era

 

At present, the automobile industry has entered a period of great change once in a century, and automobile electrification is becoming a new development trend and trend. Under the wave of electrification, the design of various major systems of automobiles has undergone earth-shaking changes. Not only are these major assemblies such as engine gearboxes undergoing a change, but the replacement of new and old parts materials and designs is also rapidly refreshing the entire industrial chain.

 

At present, advanced ceramic materials are accelerating by virtue of their special performance advantages."Get in the car". From bearings, brake pads, substrates, capacitors, relays and other parts to the efficient cutting of auto parts, the advantages of advanced ceramic materials are fully utilized in the new energy automobile industry.

ceramic substrate

In electric vehicles, high-power packaging devices are used to regulate vehicle speed and storage.-Converting AC and DC plays a decisive role. The high-frequency thermal cycle puts forward strict requirements for the heat dissipation of electronic packaging, and the complexity and diversity of the working environment require the packaging material to have good thermal shock resistance and high strength to play a supporting role.

 

Silicon nitride substrate, photo source: Zhengtian New Material

 

In recent years, the ceramic substrates that have been mass-produced and widely used are:Al₂O₃,BeO、SiC、Si₃N₄,AlN et al. Among them, silicon nitride is recognized as the best ceramic substrate material with high thermal conductivity and high reliability at home and abroad. At the same time, Si₃N₄The thermal expansion coefficient of the ceramic substrate is related to the first3 generation semiconductor substrate SiC crystal close, so that it can be more stable with SiC crystal material matching. This makes Si₃N₄Become No.The first choice of high thermal conductivity substrate material for 3 generation SiC semiconductor power devices.

ceramic bearing
Under the wave of electrification, the design and supply chain of bearings as a small component are also continuously changing. The industry believes that the challenges of the development of electric vehicles to the bearing industry are mainly presented in the following aspects:
The first is high speed. Nowadays, new energy vehicles put forward higher and higher requirements for motor speed.20,000-25,000rpm, which is a severe challenge for bearings, which comes from the limitation of durability and extremely high speed. At the same time, the flat wire motor has gradually become a technical trend, which not only increases the power density, but also brings a new test to the lubrication and heating of the bearing.

Photo Source: Yangzhen Bearing

 

Second is low noise. Low noise vibration is the key to a good user experience in electric vehicles, however, the high speed trend of the motor gives the whole machineNVH poses no small challenge, and bearings are one of the key factors in NVH control.

 

Moreover, the problem of electric corrosion is also in the process of motor development. in the traditionIn the 400V electric drive system, the electric corrosion of steel ball bearings is very common. In the 800V high voltage system, with the large-scale use of SiC substrate inverter, high voltage and high switching frequency will further aggravate the occurrence of electric corrosion.

 

Another point is the challenge of lightweight motors. In the new design, the number of bearings used is less and less, and the design is more and more compact, which puts forward higher requirements for the lightweight and durability of the bearing.

 

Ceramic materials, especially silicon nitride ceramic bearings, are considered to be the best materials for manufacturing automotive bearings because of their lightweight, high hardness, high strength, low friction, high heat resistance, excellent electrical insulation and long life.

MLCC

Chip multilayer ceramic capacitors (MLCC) is known as "electronic industry rice" and is one of the world's largest passive electronic components. Almost all consumer electronics use MLCC components.

 

 

MLCC also has a large number of applications in traditional fuel vehicles, but at present, the "new four" of automobiles (electrification, intelligence, networking, and sharing) are becoming a new development trend and trend, and MLCC has found more Moisturizing soil. The functions of automotive electrification, intelligence and networking are realized through functional modules composed of various electronic components. As a common basic component, MLCC is one of the most used passive components.

 

 

Different modelsMLCCthe demand

models with different degrees of electrification,The demand for MLCCs also varies, with a pure electric vehicle requiring up to 18000 MLCCs. With the deepening of the trend of the new four-in-the-car, the demand for MLCC is growing.

 

Carbon ceramic brake pads

 

Brake materials have undergone the development from asbestos materials, semi-metallic materials, powder metallurgy materials to carbon-carbon composites and carbon-ceramic composites. Powder metallurgy brake materials have the disadvantages of easy bonding at high temperature, easy degradation of friction performance, significant decline in high temperature strength, poor thermal shock resistance, and short service life; andC/C brake material has the problems of low static and wet friction coefficient (wet state relative to dry state attenuation of about 50%), large thermal reservoir volume, poor oxidation resistance, long production cycle and high production cost, which restrict its further development and application.

 

 

Carbon ceramic composite brake material isA multi-phase composite brake material developed in the 1990 s with high-strength C fiber as reinforcement and pyrolytic C, SiC, etc. as the matrix is based on the C/C composite brake material. SiC ceramic hard material with excellent oxidation resistance is introduced as the matrix, which not only maintains the advantages of low density and high temperature resistance of C/C composite brake material, it also overcomes the shortcomings of low static friction coefficient, large wet attenuation, insufficient friction life and poor environmental adaptability of C/C brake materials, and becomes a new generation of brake materials.

Power battery
1. Ceramic diaphragm
Lithium-ion batteries are mainly composed of five parts: cathode material, anode material, separator, electrolyte and packaging material. The separator is the highest technical barrier in lithium-ion battery materials, and its cost ratio is second only to the positive electrode material, about.10%~14%In some high-end batteries, the proportion of diaphragm costs even reaches.20%.

Relay ceramic housing (source: Andias)

 

At high temperatures, traditional separators will shrink or melt, causing internal short circuits, leading to fires and even explosions. In response to this situation, people have taken a variety of methods to improve the thermal stability ofPPorPECoating the separator with a layer of inorganic ceramic particles is considered to be the most effective and economical method. Currently commonly used ceramic materials includeΑ-Alumina, boehmite.

2Electrode Addition Material
Nowadays, more and more ceramic powders are used as cathode materials for lithium-ion batteries. For example, high-purity alumina is used for surface coating of lithium cobalt oxide (LiCoO₂), lithium manganate (LiMn₂O₄), lithium iron phosphate (LiFePO₄), ternary materials (Li-Ni-Co-Mn-O) and other positive materials can effectively improve the electrochemical performance of positive materials. At the same time, more and more lithium battery designs begin to use nano-composite zirconia powder as a positive electrode additive material to stabilize battery performance and increase cycle life.

 

Ceramic seal ring

The sealing ring is located under the battery cover plate and is used to form a sealed conductive connection between the power battery cover plate and the pole, ensuring that the battery has good sealing performance, blocking the leakage of electrolyte, and providing a good closed environment for the internal reaction of the battery. At the same time, when the battery cover is pressed down, it can also play a decompression and buffer purpose to ensure the normal operation of the internal components of the battery, which is an important guarantee for the life and safe supply of the battery. 

Photo Source: Mei Cheng Ceramics
At present, most plastic or glass seals will fail under pressure, which will affect the service life of the battery. Some special batteries obviously can not meet its requirements, which requires some new sealing ring of other materials. Ceramic materials have good acid and alkali resistance, corrosion resistance, high temperature resistance and other characteristics, making it a new choice. Now ceramic sealing ring It is also increasingly used in the power lithium battery industry.

 

ceramic relay

Electronic control technology is an important symbol to measure the development level of new energy energy-saving electric vehicles, and the high-voltage DC ceramic relay is the core component of the electronic control system. In the high-voltage DC vacuum relay, in the vacuum chamber sealed by metal and ceramic, the ceramic insulator is slidably connected between the moving contact assembly and the push rod, so that the moving contact and the static contact maintain good electrical insulation with the magnetic circuit system composed of the magnetic yoke plate, iron core and other parts of the relay in any state when the conduction is disconnected, thus ensuring the arc breaking capability of the relay when switching DC high voltage loads, arcing is the main cause of auto-ignition. Only adopt"No arc" on-off relay products, is the fundamental solution to the problem of "spontaneous combustion. 

Relay ceramic housing (source: Andias)
At present, in the international high-voltage DC relay only Japan Panasonic, the United StatesTECompanies and South Korea well-known companies can produce, the product price is higher. Domestic enterprises in the field of high-voltage relay research and development, production is still in its infancy.
ceramic fuse

The fuse is a device that protects the circuit from overcurrent. In operation, the fuse is connected in series in the circuit, and the load current flows through the fuse. When the circuit is short-circuited or overloaded, the thermal effect of overcurrent melts and vaporizes the melt to produce a fracture, and the fracture produces an arc. The fuse cuts off the fault circuit by extinguishing the arc to protect the circuit.

Ceramic tube new energy fuse (source: Asahi Electronics)

 

Automotive fuses are divided into low-voltage and high-voltage two parts, high-voltage protection is mainly suitable for new energy vehicles, the application voltage is generally 60VDC-1500VDC, mainly power fuse (new energy vehicle high-voltage fuse) to protect the main circuit and auxiliary circuit. With the new energy vehicle market entering the post-subsidy era, personal consumption demand promotes the high-voltage platform of new energy vehicles. The safety requirements in high-voltage fields such as fast charging, motors and power devices cannot be ignored. The fast breaking capacity of fuses in stability and overcurrent reaction will maintain the high-speed increase of demand under the rapid growth of new energy vehicles.

LED Car Light-Sapphire Substrate (High Purity Alumina)

In 2022, affected by the shrinking consumer demand in the downstream market, the traditional LED lighting market performed in a downturn, while the automotive LED market rose against the trend due to new energy vehicles.

 

 

Morphological evolution of alumina during the growth of sapphire

 

The LED substrate is made of sapphire material. The advantages of sapphire substrate are mainly manifested in the aspects of stable device, mature preparation technology, non-absorption of visible light, good light transmittance, and moderate price. Data show that 80% of LED enterprises in the world use sapphire as substrate material. The raw material for preparing the sapphire substrate is high-purity alumina, which needs to have a high purity and a very low moisture content in the raw material.

spherical alumina

Adhesives are widely used in power battery assembly.PACK sealing, structural bonding, structural heat conduction, battery potting, etc., provide safety protection, lightweight design, thermal management and other functions, and play a key role in achieving lasting, stable, efficient and safe operation of power batteries. In terms of electronic control, the rigid interface between the IGBT module and the cold surface needs to be coated with thermal silicone grease to reduce thermal barrier; in the drive motor, the stator is used to generate rotating magnetism, and the stator is usually potted with high thermal conductivity glue. As a thermal interface material, spherical alumina has important applications in the above three aspects.

 

Summary

 

In addition to the ceramic materials listed above, there are many ceramic powders or products that are not directly on the car, but they play an important role in the production of auto parts. For example, in the sintering process of lithium battery cathode materials, ceramic kiln furniture such as push plate, sagger and roller bar are essential. The cutting of metal parts needs ceramic tools to complete. In addition, in the low-pressure casting of automobile aluminum alloy wheels, key components such as sprue sleeve, sprue cup, runner, pipette and degasser rod are all ceramic products, playing a key role.

 

Reference Source:[1] Zhou Xiwen. Application of ceramic materials in the automotive industry [2] Wu Yuhong. The application of ceramic materials in automobiles [3] Li Ting. Brief introduction and application of automotive ceramic materials [4] China Powder Network

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