Why Broken Carbon Fiber Heater Tubes Can’t Be Reused

Today, while browsing through records, I came across a friend’s query about whether damaged heating tubes can be salvaged. Specifically, “Can broken outer tubes of carbon fiber heater elements be reconnected and still used?” Let’s analyze why both carbon fiber heater elements and tungsten wire infrared heating tubes cannot continue to be used when their outer tubes crack.

Both grijaći elementi od karbonskih vlakana and tungsten wire infrared heating tubes consist of electric heating wires enclosed within quartz tubes, processed through vacuum sealing or the introduction of protective gases.

The electric heating wires in these two types of heating tubes are made of carbon fiber and tungsten, respectively. The properties of these materials dictate that they must be operated under vacuum or in a protective gas environment to function properly.

Carbon fiber, when powered in air, oxidizes and loses its physical properties after reaching a certain surface temperature, leading to rapid burnout. However, it can be used for extended periods in low-temperature environments. For instance, carbon fiber silicone wires used in underfloor heating systems operate below 75 degrees Celsius. Carbon fiber wires are suitable only for civilian applications in low-temperature fields such as underfloor heating, wall heating, low-temperature heaters, health care products, and low-temperature physiotherapy devices.

In industrial electric heating tube applications, however, 75 degrees Celsius falls short of operational requirements. The physical and chemical properties of carbon fiber are highly stable in low-temperature environments but unstable at high temperatures. In vacuum or protective gas atmospheres, carbon fiber demonstrates stable physical and chemical properties, capable of withstanding temperatures up to 2700 degrees Celsius. This is why carbon fiber must be used as an electric heating wire in a vacuum or protective gas environment.

The electric heating wire inside tungsten wire infrared heating tubes is made of tungsten, a material selected by Edison during the invention of the light bulb. Tungsten can reach incandescent state and emit heat and light in vacuum or protective gas environments.

Tungsten is a refractory metal with the highest melting point. Metals with a melting point above 1650 degrees Celsius and higher than zirconium’s melting point (1852 degrees Celsius) are known as refractory metals. Typical refractory metals include tungsten, tantalum, molybdenum, niobium, hafnium, chromium, vanadium, zirconium, and titanium. Tungsten’s key advantage lies in its excellent high-temperature strength and corrosion resistance to molten alkali metals and vapors. Tungsten volatilizes and oxidizes only above 1000 degrees Celsius in the presence of oxygen. However, it also exhibits a high ductile-to-brittle transition temperature and is difficult to process at room temperature due to its plasticity.

Refractory metals such as tungsten are widely used in metallurgy, chemical industry, electronics, light sources, and mechanical industries. In the presence of oxygen, tungsten oxidizes and burns at high temperatures.

Due to its tendency to sublime and evaporate at high temperatures, tungsten often exhibits a common phenomenon. For example, incandescent bulbs, especially those with a power rating exceeding 100 watts, develop a dark substance on the outer glass after some use, which results from tungsten sublimation and deposition on the quartz surface.

GlobalQT specializes in high-quality quartz tubes and heating elements. For more information, visit our web stranica ili nam pošaljite email na contact@globalquartztube.com.