Carbon brush, also known as brush, as a sliding contact, in many electrical equipment has been widely used. Carbon materials in the application of products are mainly graphite, graphite impregnated graphite, metal (including copper, silver) graphite. The carbon brush is the energy transfer device or signal between motor or generator or other rotating machinery of the fixed part and the rotating part, it is generally made of pure carbon coagulant, the general shape is square, stuck in the metal bracket, which has spring pressed it on the shaft, when the rotation of the motor, the power through the change which is delivered to the coil, as its main components are carbon, known as carbon brush, it is easy to wear. Should be regularly maintained to replace and clean up carbon deposits.

　　The carbon brush looks a bit like a pencil eraser. The volume is large and small. Carbon brush, as a sliding contact, has been widely used in many electrical equipment. The main products are graphite, graphite, graphite, metal (including copper, silver) graphite.

　　It is mainly on the effect of carbon brush and conductive metal friction; it's not like metal on metal friction as conductive metal on metal friction; conductive; friction force can be increased; at the same time where the transfer may be sintered together; and the brush is not; because the carbon and metal are two different elements of it; use mostly used in motor; shape is various; square and round etc..

　　The carbon brush is suitable for all kinds of motors, generators and wheel axles. It has good performance and long service life. The carbon brush is used for motor commutator or slip ring, as sliding contact body import and export current, its thermal conductivity, and good lubrication performance, and has certain mechanical strength and direction of the spark of instinct. Almost all motors use carbon brush, which is an important component of the motor. Widely used in all kinds of AC and DC generator, synchronous motor, battery DC motor, crane motor collector ring, various types of electric welding machine, etc.. With the development of science and technology, the types of motor and the working conditions are becoming more and more diversified

　　Specific function

　　1 the external current (excitation current) through the carbon brush to the rotor (input current);

　　2 the static charge on the main shaft is introduced into the earth by the carbon brush (grounding carbon brush);

　　3 the main shaft (ground) to the protection device for rotor grounding protection and measurement of positive and negative rotor voltage;

　　4 change the direction of the current (in the commutator motor brush, also plays a role reversal)

       Carbon brush is a device which conducts current between stationary wires and moving parts,most commonly in a rotating shaft. it's a sliding contact used to transmit electrical current from a static to a rotating part, in a motor or generator, and as regards DC machines, ensure a spark-free commutation. typical applications include electric motors, alternators and electric generators.

　　Carbon brushes are maintained by brush-holders to be in permanent contact with the slip ring assembly or with the commutator.

　　Carbon Brushes are used in general industrial such as DC motors, Electrical trains, Wind-generated power. industrial carbon brushes are used on large commutator machines, in which the current between the rotor and external circuit is periodically reversed. These include AC and DC motors, slipring rotors, traction motors, turbogenerators, windmills, hydro power stations and steel, cement and paper mills. Industrial carbon brushes also can be used to power battery-driven cars, cable cars and trolley buses, and they are often used in construction vehicles such as forklift trucks and cranes. Brushes connect the generator to the rotor through the commutator, which has copper segments, or lands. The brushes bear the brunt of wear and tear between the rotating rotor and the non-moving generator while conducting electricity between them. Industrial brushes are specially designed to withstand extreme temperatures.

　　The home application of carbon brushes as the power tools like washing machines and disk grinders.carbon brushes are a common component in household appliances such as power tools, gardening equipment and office equipment. Vacuum cleaner turbines, hair and hand dryers, and washing and drying machines are also common applications of this type of carbon brush, which is generally much smaller than its industrial or automotive counterparts. Micro-carbon brushes, for example, are precision parts designed for toys, electric razors, and audio and video equipment. In such small dimensions, carbon brushes are often placed inside tiny battery-operated mini-motors designed to transmit power silently and with the least amount of friction to moving parts such as wheels and razors.

　　As to automotive application of carbon brushes, we will think of automobiles and forklifts.cars generally use small and auxiliary carbon brushes for DC motors, starters and alternators. Alternators are devices that convert mechanical energy to electrical energy. They consist of a wire-coiled rotor that produces a magnetic field when a current runs through it. Automotive carbon brushes are used to supply the current to the wire coil in the alternator. Automotive carbon brushes can be found in most passenger vehicles, motorcycles, trucks and oil- and diesel-fueled cars. Even smaller, specially designed carbon brushes are used in steering wheels and contacts for airbags.

　　The performance and application of carbon brushes in the pulp and paper environment. direct current (DC) motors are used extensively throughout the pulp and paper industry. the motors are used in various applications such as fan pumps, press and winder motors. The maintenance requirements of the motors are different for each application. An important maintenance function regularly performed is the inspection of carbon brushes and commutators. Carbon brushes are critical to the operation of the paper machine with DC motors. Worn or failed brushes can make a paper machine inoperable and cost thousands of dollars per hour.

　　Graphite is formed at high temperatures, is the most widespread graphite metamorphic deposit，By rich in organic matter or carbonaceous sink Indicates the regional metamorphism Graphite and graphite products in industry application is very wide, used for smelting.　The high temperature of crucible, mechanical industrial lubricants, making the electrodes and pencil lead

　　Graphite and graphite products are widely used in High-grade refractory material and coating of metallurgy industry, military industry, fire engineering materials stabilizer, light industry of pencil lead,The carbon brush of electrical industry, battery industry electrode catalyst, chemical fertilizer industry, etc.Flake graphite after deep processing,But also produce graphite,Graphite sealing material and composite material,，Graphite products,Graphite antifriction additives etc New technology of graphite products, graphite or graphite products become important nonmetallic mineral raw material of each industrial sector.most of world graphite or graphite products production consumption are concentrated in Japan,The United States,Germany and the UK, etc，Industry developed countries,Graphite has good corrosion resistance.

　　Carbon brushes are a type of graphite parts.Carbon brushes with a resin binder were prepared according to an industrial process and the effects of the molding pressure, grains size and cure temperature on the properties of brush samples were discussed. Four kinds of high-resistivity carbon brushes with MoS2 contents of 0%,2%,4%and 6%(mass fraction)were prepared, respectively.Wear tests of brushes were conducted on an alternate current(AC)motor.Scanning electron microscopy(SEM)and energy dispersive X-ray analysis(EDS)were used to analyze the worn surface of brushes,and a thermocouple was used to measure the bulk temperature of the brush.The results show that wear rate of brush made without MoS2 in 10%relative humidity(RH)is two times larger than that in 50%RH,whereas the wear rates change little for the brushes made with MoS2.The wear of brushes has much to do with the surface film.In low humidity,the surface film can not be formed for the former brush while a sulfur layer can be formed for the latter brushes,which can reduce sparks,frictional heat and wear rate,and play a role like the water film in high humidity.

　　The results show that the bulk density, bending strength and Rockwell hardness increase, while resistivity decreases with increasing molding pressure. Cure temperature has much more influence on the properties of brushes than molding pressure and grains size. Isothermal differential scanning calorimetry(DSC) was used to estimate the degree of cure of resin binder and a novel method of using the true density to measure the degree of cure of resin binder was presented and discussed briefly. Based on optimal process parameters carbon brushes were manufactured, durability tests for brushes were carried out on an alternate current motor and scanning electron microscope(SEM) was adopted to observe the morphology of worn surface of brushes. The results show that a luster oxide film can be formed on the surface of brushes and their service life reaches 380 h.