What are the conductive composite materials and what are the conductive materials

According to the structure and composition of the material, conductive polymer materials can be divided into:

Structural conductive polymer materials and composite conductive polymer materials. Structural (or intrinsic) conductive polymers are the "intrinsic" conductivity of the polymer material itself, and the carrier is provided by the polymer structure.

After these polymers are doped, the conductivity.

Dramatically improved, some can reach the level of conductivity of metals; Composite conductive polymer materials refer to polymer materials that are not conductive by themselves, but are processed and molded by adding conductive fillers, such as carbon black.

Metal powder, foil, etc., through dispersion composite, layer-based composite, surface composite, etc., to make the product conductive, of which dispersion composite is the most commonly used.

At present, conductive composite materials mainly refer to composite conductive polymer materials, which are composed of polymers and various conductive substances through a certain composite method For a long time, polymer materials are usually used as insulating materials.

It is widely used in electrical industry, installation engineering, communication engineering, etc.

Composite materials are divided into: structural composite materials and functional composite materials, and conductive composite materials belong to functional composite materials!

Classification of Composites:

1. Metal matrix composites;

2. High polymer matrix composites: resin matrix composites (including thermosetting and thermoplastic), rubber matrix composites;

3. Ceramic matrix composites: carbon and its carbonaceous matrix composite materials, non-carbonaceous matrix composites;

Among them, 2 and 3 are non-metallic matrix composites, theoretically the above composites can be modified to conduct electricity or have conductive properties themselves, if you want to understand professionally, you have to read more books on functional composite materials.

Commonly used conductive materials are copper and aluminum. Of course, gold and silver are also conductive materials, but they are not commonly used.

The ability of an object to conduct an electric current is called conductivity. The conductivity of various metals varies, and generally silver has the best electrical conductivity, followed by copper and gold.

The Biming conductivity of solids refers to the long-distance migration of electrons or ions in solids under the action of electric fields, usually dominated by one type of charge carrier, such as: electron conductors, with electron carriers.

conductive for the main body; ionic conduction, conduction with ion carriers as the main body; Hybrid conductors with both carrier electrons and ions.

Conductors of electricity. It is an object that conducts electricity easily, that is, it is able to pass an electric current through the material; Objects that do not easily conduct electricity are called insulators.

It is not that the object that can conduct electricity is called a conductor, and the object that cannot conduct electricity is called an insulator, which is a common mistake made by ordinary people) Wang talks about the free movement of electrons in metal conductors, and the reason for conducting electricity is free electrons. Semiconductors vary with temperature and their resistivity.

The gradual decrease in the number of difficulties decreases, and the conductivity is greatly improved, and the conductive reason is the holes and electron pairs in the semiconductor. Ohms are commonly used in science and engineering.

to define the degree of electrical conductivity of a material.

Commonly used metal conductive materials can be divided into four categories: metal elements, alloys (copper alloys, aluminum alloys, etc.), composite metals and other special purpose conductive materials that do not take conductivity as their main function: metal elements, alloys, composite metals, and special functional conductive materials.

Main properties: The electrical properties of conductive materials are mainly characterized by resistivity. Factors that affect resistivity include temperature, impurity content, cold deformation, heat treatment, etc.

The effect of temperature is often expressed as the temperature coefficient of the resistivity of a conductive material. Except for close to the melting point and ultra-low temperatures, the resistivity is linear with temperature in the general temperature range.

Composite polymer conductive materials are made by general polymer materials and various conductive substances through filling composite, surface composite or layered composite. The main varieties are conductive plastics, conductive rubbers, conductive fiber fabrics, conductive coatings, conductive adhesives and transparent conductive films.

Its performance has a great relationship with the type, dosage, particle size and state of conductive fillers and their dispersion state in polymer materials. Commonly used conductive fillers include nickel-clad graphite powder, nickel-clad carbon fiber carbon black, metal powder, metal foil, metal fiber, carbon fiber, etc.

Conductive materials for electrical materials.

Conductive materials ranking: silver, copper, gold, aluminum, nickel.

1. Silver

Silver is an excellent conductive material, and its conductivity is the best of all metals. Silver is used in a wide range of applications, such as low-noise radios, high-performance connectors, sensors, and batteries.

2. Copper

Copper is a widely used highly conductive material, and its conductivity is slightly inferior to silver. Due to the relatively low ** of copper, it is often used to replace the position of silver in practical applications. Copper is also widely used, involving electronics, communications, electricity, 5 and other fields, and is often used in the manufacture of various wires, cables, plug-ins and connectors.

3. Gold

Gold is a highly conductive material, second only to silver in terms of its properties. Gold has excellent oxidation resistance and chemical stability, so it is often used in the manufacture of wires and circuit boards in high-temperature and high-humidity environments. Although gold is relatively expensive, it is still widely used in some special fields, such as jewelry processing, high-end consumer electronics, etc.

4. Aluminum

Aluminum is an excellent conductive material, and its conductivity is comparable to that of copper. Aluminum has a wide range of applications and is commonly used in the manufacture of various wires, cables, heat sinks, connectors, connectors, etc. Compared with copper, aluminum has more advantages, so aluminum replaces the position of copper in some fields, such as power transmission, aerospace, etc.

5. Nickel

Nickel is a highly conductive material with properties comparable to copper. Nickel has excellent oxidation resistance and chemical stability, so it is commonly used in the manufacture of various wires, cables, connectors, connectors, etc. Compared with copper, nickel has more advantages, so nickel replaces the position of copper in some fields, such as the chemical industry, aerospace, etc.

Carbon fiber has excellent properties such as high specific strength, high specific modulus, high temperature resistance and electrical conductivity, and has advantages in fields where density, stiffness, weight, and fatigue characteristics are required, and has an irreplaceable role in aerospace, aviation, weapons, ships, nuclear and other national defense fields.

The resistivity of carbon fibers is related to its composition, graphitization degree, defects, etc., which are characterized by semiconductors, low temperature is mainly controlled by impurities, and high temperature is characterized by electronic conductance. The commonly used test methods for the resistivity of the masking commotion are the voltage, current method and the bridge method, the former is divided into double probe method and four probe method, the latter is divided into single bridge method and double bridge method, four probe method and double bridge method can eliminate the influence of contact resistance and lead resistance, suitable for low resistance test, and the resistivity of carbon fiber can be tested by four point probe method.

Resistivity, also known as bulk resistivity, is generally determined by the four-probe method, the resistivity of carbon fiber is related to the raw material, but also closely related to the heat treatment temperature, graphitization degree and structural parameters, generally speaking, the resistivity of mesophase asphalt-based carbon fiber is smaller than that of pan-based carbon fiber, and the resistivity of pan-based carbon fiber is smaller than that of viscose-based carbon fiber. However, regardless of the type of carbon fiber, the resistivity decreases as the heat treatment temperature increases.

Resistivity vs. crystallinity. Raman spectroscopy was used to analyze the crystallinity of carbon fibers, and with the increase of HTT, the strength of the crystalline region increased, and the strength of the amorphous region decreased, reflecting the increase of graphitization degree and the decrease of resistivity.

Effect of heat treatment temperature on resistivity. With the increase of heat treatment temperature, the density of pan-based carbon fiber increases in waves, while the resistivity plummets. The linear increase in density before 1000 is due to the removal of non-carbon elements and the axial elongation and radial contraction under the action of drafting.

Generally speaking, as the heat treatment temperature increases, the degree of graphitization also increases, and not only the graphite layer increases, but also is arranged in an orderly manner along the axis, resulting in a decrease in resistivity. In addition to the resistance and length, resistivity is also related to its titer and density.

Structural type (or intrinsic type) conductive polymer materials are the "intrinsic" conductivity of the polymer material itself, and the polymer structure provides the carriers. After some polymers are doped, the conductivity is greatly improved, and some can reach metallic ones.