Application of Piezoelectric Ceramics in Smart Cars
“Intelligence” is the core keyword and main line of the automotive industry: intelligent driving, intelligent cockpit and intelligent Internet connection have become the main parts of the current automotive intelligence. From the current popular L2 level automatic driving to the future L4 / L5 high-level automatic driving, the average incremental value of a single vehicle brought by intelligence may be tens of thousands of yuan.
The material industry is the cornerstone of modern industry, and in the intelligent automobile industry, the application of various advanced materials is also the basis of supporting the whole industry. Here, let’s learn about ceramic materials, which play an increasingly important role in the process of automotive intelligence.
1、 Classification and performance advantages of ceramic materials
Ceramic material is a large category, which refers to a kind of inorganic non-metallic materials made from natural or synthetic compounds through shaping and high-temperature sintering. It has the advantages of high melting point, high hardness, high abrasion resistance and oxidation resistance. The new ceramic materials used in modern industry are mainly made from high-purity and ultra-fine synthetic inorganic compounds and sintered by precision control process. Its components are mainly oxides, nitrides, borides and carbides.
At present, ceramic materials commonly used in the vehicle field include silicon nitride (Si3N4), silicon carbide (SIC), zirconium dioxide (ZrO2), beryllium oxide (BeO), aluminum oxide (A12O3) and so on, which are used for structural and functional components on vehicles. Therefore, they are also divided into structural ceramics and functional ceramics.
To understand a material, let’s first look at its advantages and disadvantages in performance:
1. Performance advantages
The new ceramic material is an atomic crystal material. Its structure is similar to that of diamond, which is often called diamond, so its physical characteristics are also very similar in some aspects, such as high hardness. The following is a summary of the performance advantages of ceramic materials:
High hardness and accurate size: ceramic materials generally have extremely high hardness / stiffness, which directly translates into excellent wear resistance, which means that many technical ceramics can maintain their accurate and high tolerance finish for a longer time than any other material.
Compressive strength: new ceramics have very high strength, but only when compressed. For example, many precision ceramic materials can withstand extremely high loads of 1000 to 4000 MPa. On the other hand, titanium is considered to be a very strong metal with a compressive strength of only 1000 MPa.
Low density / lightweight: another common characteristic of precision ceramics is their low density, from 2 to 6 g / cm ³。 This is lighter than stainless steel (8 g / CC).
High dielectric strength (insulation): they are particularly useful in high temperature applications where the mechanical and thermal properties of other materials tend to deteriorate. Some ceramics have low electrical loss and high dielectric constant; These are commonly used in electronic applications such as capacitors and resonators. In addition, the combination of insulators and structural components has generated many product innovations.
High temperature resistance: ceramic material is an ultra-high temperature material, and its melting point temperature mostly exceeds 1500 ℃. At present, there are some cases in high-temperature applications such as engines, turbines and bearings.
Thermal conductivity and insulation properties: the thermal properties of different types of ceramic materials are very different. Some ceramics (aluminum nitride) have high thermal conductivity and are usually used as radiators or exchangers in many electrical applications. Other ceramics have much lower thermal conductivity, making them suitable for a wide range of applications.
Chemical inertness and corrosion resistance: ceramic materials have very good chemical stability and low chemical solubility, so they have high corrosion resistance. Metals and polymers cannot provide the same inertness or corrosion resistance, which makes ceramics an attractive choice in many commercial and industrial applications, especially when abrasion resistance is also required.
2. Disadvantages of ceramic materials
While having the above advantages, ceramic materials inevitably have some difficulties; Poor shear and tensile strength, high brittleness and poor ductility; It is difficult to design and process.
Thanks to the excellent electrical, mechanical and heat resistance of ceramics, they are more widely used in the strict requirements of vehicle specifications. For example, it is used as various electronic components such as resistors, capacitors and inductors; Because of its excellent thermal conductivity, it can be used for ceramic substrates of various power devices and sensor chips; In addition, ceramics can also be used in traditional fuel engines, new energy lithium batteries, brake pads, ceramic valve pads, etc.