Several technical key points affecting the performance of carbon fiber quartz electric heating tubes：
Carbon fiber quartz electric heating tube is a high-tech product that is different from traditional electric heating tubes such as metal wires and halogens. It has long service life, high electric heating conversion efficiency, far-infrared radiation, health and environmental protection and other excellent properties. It has been widely used in industry and daily use. The electric heating field.
1- Classification of carbon fiber electric heating tubes: There are many types of carbon fiber electric heating tubes. The classification method can be roughly classified according to five major aspects: heating element type, tube filling gas, quartz tube surface coating, heating tube outlet end, and heating tube shape structure.
2-Technical key points: Taking carbon fiber infrared quartz heating tube as an example, its product structure is that the carbon fiber bundle is wound into an empty spiral shape and then solidified and sealed in a quartz tube, which is set in a vacuum state or protected by inert gas. The technical factors that will affect the electric heating performance and service life of the electric heating tube are roughly as follows.
2.1 The impact of carbon fiber yarn treatment process on product life The most common carbon fiber yarn treatment methods are mainly three ways: weaving carbon fiber yarn into felt shape, weaving into rope, and twisting into rope. Carbon fiber woven felt has the problem of unstable power when used as a heating element. This is because carbon fiber felt is a foamed pore-like substance. At present, it is difficult to ensure that the thickness of carbon fiber felt and its pore distribution are in an ideal and uniform state. It is also difficult to control deviations during width cutting, which will cause heating of the heating element. Uneven, the power is difficult to accurately control. When the temperature of the working surface of the heating element reaches 450 or above, the impurities on the surface will gradually decompose and gradually fill the micropores of the carbon fiber felt. At high temperature, the carbon fiber volatiles will gradually fill the micropores of the carbon fiber felt, making the electrode sheet The resistance of the structure composition is small and the power increases sharply, causing the quartz shell of the electric heating tube to burst and damage.
Carbon fiber yarn is woven into a rope shape or twisted to form.From the perspective of processing technology, carbon fiber yarn is woven into a rope shape, and several carbon fiber yarns are often pulled and broken, resulting in many burrs on the surface of the carbon fiber yarn after weaving. Affect the appearance, in some cases bright spots will appear when working. Multi-strand rope twist forming can not only improve the electric heating characteristics of the heating element, but also effectively reduce the surface temperature of the heating element, reduce the surface load, and greatly increase the service life of the heating element.
2.2 The effect of carbon fiber bundle curing process on service life. After the carbon fiber filament is twisted or woven into a rope shape, it needs to be wound into a spiral by manual or equipment. The carbon fiber bundle wound on the mandrel must be cured. In this way, the carbon fiber bundle can maintain the hollow spiral shape after being withdrawn from the mandrel. The curing treatment of carbon fiber bundles mostly uses epoxy resin as curing agent for gluing, and then puts them in a hydrogen-burning furnace for high-temperature impurity removal. If the curing agent is brushed too thickly during gluing, it may cause the residual impurities on the surface of the carbon fiber bundle to be incompletely volatilized.After the electric heating tube is energized, these impurities volatilize and adhere to the inner wall of the quartz tube, causing stains to affect the appearance, and may also cause the carbon fiber bundle Rigidity is too large, broken wires or strains occur during the process of carbon fiber bundle piercing and clamping; if the glue is uneven, it will also cause local bright spots on the heating element, which will affect the appearance of the product; if the amount of glue is too small, it may There will be loose filaments or insufficient rigidity of the carbon fiber bundles, and the phenomenon of filaments falling after a period of work will seriously affect the service life of the electric heating tube.
In the case of a certain carbon fiber electric heating power, how to correctly select the appropriate length and diameter of the carbon fiber bundle, the winding density of the carbon fiber yarn, the number of braided strands, and the value of the pitch must be considered whether it will cause excessive surface load on the heating element. These factors will directly Affect the service life of the heating element.
2.3 The influence of electrode structure on service life When carbon fiber woven felt is used as a heating element, it is often simply wound with the metal electrode terminal, but this has great defects. Its contact resistance is more than 2 and the surface load of the contact is as high as tens of per square centimeter. Above watts, the temperature is much higher than the heating element, the long-term energization potential difference will continue to increase, the contact is easy to burn, and the life of the heating tube is difficult to guarantee. Carbon fiber filaments are woven or twisted into a rope, and after being wound into a hollow spiral shape, they need to be connected with the lead material between the power sources. The lead material is mostly a metal wire with good conductivity. If the power design of the electric heating tube is too high, in addition to the necessary cold zone, a refrigeration device (mostly air-cooled) needs to be installed outside the lead end to avoid the breakage of the lead end electrode sheet due to heating and expansion. . The connection form mostly uses the electrode sheet, which is usually led by molybdenum sheet and molybdenum rod spot welding.
2.4 The influence of the gas filled in the tube on the service life The carbon fiber begins to oxidize in 350 air, and it begins to vaporize when it exceeds 400.