ZHENGZHOU SONGYU HIGH TEMPERATURE TECHNOLOGY CO.,LTD

Silicon carbon rod, silicon molybdenum rod production process

Carbon rod (silicon carbon rod) production process Raw material preparation: high-purity silicon carbide powder is acid-washed and alkaline-washed to remove impurities, mixed with phenolic resin binder and a small amount of additives to make a plastic blank. Molding: straight rods are extruded, and complex special-shaped parts are isostatically pressed (100-200MPa high pressure compaction) to obtain a blank of a set shape. Drying: 60-150℃ step-by-step drying to remove moisture and volatiles to prevent sintering cracking. Sintering: 1600-2200℃ sintering in an inert atmosphere, silicon carbide particles are combined through solid phase diffusion to form a dense structure. Electrode treatment: metal slurry is sprayed on both ends and baked to form a conductive layer, and the size is corrected by grinding to complete the finished product. Molybdenum rod production process Molybdenum powder preparation: ammonium molybdate is calcined to generate molybdenum trioxide, and then hydrogen is two-stage reduced (500-1100℃) to obtain high-purity molybdenum powder (purity ≥99.95%).​ Molding: Molybdenum powder is loaded into the mold and pressed into a green billet by cold isostatic pressing (150-200MPa). ​ Sintering: High temperature sintering at 1800-2200℃ under hydrogen protection, molybdenum powder particles are fused, and the density reaches more than 98% of the theoretical value. ​ Processing and heat treatment: 1200-1400℃ hot rolling or forging to reduce diameter and improve strength; 1000-1200℃ hydrogen annealing to eliminate stress. ​ Finishing: Fine grinding of the outer circle to control tolerance (±0.02mm), cutting to a fixed length to ensure that the surface roughness meets the standard. ​ Both require strict control of raw material purity, and rely on protective atmosphere to prevent oxidation during production. Carbon rods focus on sintering process to control conductivity, while molybdenum rods are key to reducing powder and hot processing to ensure strength. In the end, both need to pass density and resistivity tests to ensure quality.

Factors affecting the service life of heating elements

The service life of silicon - molybdenum rod electric heating materials is impacted by a multitude of factors. Beyond the inherent quality disparities of the components themselves, it’s also undermined by aspects like the operating temperature of the components, the surface load on the hot sections of the components, the ambient natural environment (including atmospheres and hazardous substances), power supply modes (intermittent vs. continuous operation), as well as the series - parallel connection arrangements during the application process, and the load conditions of the components across different temperatures. In terms of corrosion resistance, silicon - molybdenum rod heating materials hold up well against acidic environments during use. Yet, in alkaline atmospheres and similar settings, the protective silica film they form gets damaged, leading to varying degrees of deterioration over their service life. Notably, these components can tolerate relatively high temperatures and surface loads when used in diverse atmospheric conditions. Silicon - molybdenum rods boast a suite of advantageous traits for high - temperature applications: they exhibit heat resistance, oxidation resistance, corrosion resistance, rapid heating capability, a lengthy service life, minimal high - temperature deformation, ease of installation and maintenance, along with excellent chemical stability. When paired with automated electronic control systems, they can deliver a stable temperature output. Moreover, they enable automatic temperature regulation following specific curves as dictated by production processes. Thanks to these merits, using silicon - molybdenum rod heating is both convenient and dependable. These rods have found extensive application in numerous high - temperature industrial sectors. This includes fields like electronic devices manufacturing, permanent magnetic materials production, powder metallurgy, ceramics, laminated glass processing, semiconductor materials fabrication, profiling and testing operations, as well as scientific research endeavors. They’re integrated into various heating apparatuses such as tunnel kilns, roller kilns, glass kiln furnaces, vacuum sintering furnaces, box - type resistance furnaces, smelting furnaces, serving as key electric heater components. However, a common headache for many users lies in the “rod breakage issue” that frequently arises during the purchasing and usage phases, causing considerable inconvenience.

Several precautions for using silicon carbon rods

1. Surface protection​   First, heat the silicon carbon rod to form a dense silicon oxide film on its surface. This film is like an anti-oxidation protective film, which can significantly extend the service life of the silicon carbon rod. During use, the gas coating in the furnace can also be used to further enhance the protection effect and prevent the silicon carbon rod from cracking. ​ 2. Temperature and current management​   Secondly, the surface temperature of the silicon carbon rod is positively correlated with the current. The higher the surface temperature, the higher the current. When using it, it needs to be strictly controlled, and its effective heating length should generally be controlled within Δ60℃. At the same time, the actual power on the surface of the silicon carbon rod is determined by the furnace temperature and the surface temperature of the silicon carbon rod. Pay attention to these two temperature parameters during operation to ensure stable operation of the equipment. ​ 3. Connection method selection​   In terms of connection, when using silicon carbon rods, parallel connection should be selected as much as possible. This is to avoid damage to the silicon carbon rod due to excessive resistance load and ensure equipment safety.

Working Principle Of SIC Heating Elements

  The working principle of silicon carbon rods is based on the semiconductor characteristics and physical and chemical properties of its main raw material, high-purity silicon carbide. From the perspective of conductivity, silicon carbide is a wide bandgap semiconductor. At room temperature, there are few free carriers and high resistance. After power is turned on, electrons absorb energy and jump to the conduction band to form current. Lattice vibration assists electron migration to reduce resistance, and when the temperature rises, the bandgap width decreases. The increase in carrier concentration causes the resistance to change with a negative temperature coefficient. In terms of the heating mechanism, following Joule's law, when current passes through the silicon carbon rod, the collision between the carrier and the lattice generates heat.   During the working process, different temperature stages show different characteristics: the resistance slowly decreases from room temperature to 400℃; the resistance decreases significantly from 400-700℃ and the oxidation rate accelerates, which requires rapid temperature rise to cross; above 700℃, a dense silicon dioxide protective film is formed on the surface, the oxidation rate slows down, and enters a stable working area. To ensure power stability, an adjustable transformer or thyristor power regulator is required to adjust the voltage in real time according to the temperature. In addition, the high thermal conductivity of the silicon carbon rod allows its heat to be quickly transferred to the surface, thereby heating the heated object through radiation and convection. The self-generated silicon dioxide protective film on its surface can prevent oxygen from penetrating and extend its service life. However, when the resistance increases abnormally, thermal stress causes mechanical fracture, or chemical corrosion destroys the oxide film, the silicon carbon rod will fail.

The research on polymer-based composite materials won the first prize of Anhui Science and Technology Progress Award

  The results of the Anhui Science and Technology Progress Award were announced, and the project "Key Technologies and Industrialization of Waterborne/Solvent-free Polyurethane Composite Materials" in which Professor Qian Jiasheng and Professor Xia Ru participated won the first prize. The project team innovatively developed key technologies for the synthesis of bio-based solvent-free and waterborne polyurethane resins and key technologies for coating interface regulation, and overcame the global industry's common key technical bottlenecks in the difficulty of balancing the environmental protection, durability and functionality of polyurethane synthetic leather composite materials.

China Composites Innovation and Corporate Sustainable Development Conference Concludes

  On June 10, 2025, the two-day "China Composites Innovation and Enterprise Sustainable Development Conference" was successfully concluded at the Hyatt Regency Songjiang, Shanghai. More than 300 industry elites, experts, scholars, and corporate representatives from around the world discussed the theme of "Composites Innovation New Quality Productivity and Enterprise Sustainable Development", analyzed the new development trend of the industry, judged future opportunities and challenges, and discussed new ideas and new paths for the composites industry to cultivate new quality productivity and sustainable development.

The 2025 Amorphous Nanocrystalline Alloy Industry Development Conference was held in Shanghai

  On June 11, the 2025 Amorphous Nanocrystalline Alloy Industry Development Conference was held at the Shanghai New International Expo Center. Nearly 100 well-known experts, scientific researchers, and corporate representatives from the fields of amorphous nanocrystalline and upstream and downstream industrial chains across the country gathered in Shanghai to discuss and exchange the latest research results, new processes, and new market expansion layout in the field of amorphous nanocrystalline. Many experts gave wonderful reports at the meeting, covering the innovation of soft magnetic materials, analysis of the amorphous alloy material industry, and the development of the magnetic material industry.

What is a porcelain furnace?

  A porcelain furnace is a device specially used for making dental restorations. It is mainly used for high-temperature sintering of ceramic materials to make crowns, bridges, veneers, etc.     Its working principle is to sinter the ceramic material and achieve the desired strength, durability and aesthetic effect through precise temperature control. Porcelain furnace plays an important role in the field of dentistry, which can produce highly precise and natural-looking dental restorations.     More specifically, a porcelain furnace is usually composed of a furnace cover, a grill, a lifting platform, and an operating panel, and can be used at a maximum temperature of 1200°C. The core function of a porcelain furnace is to sinter porcelain powder at high temperatures to produce dental restorations such as crowns, bridges, and veneers. The precise temperature control and rapid temperature rise characteristics of the porcelain furnace (for example, it takes only 7 minutes from room temperature to 1000°C and 10 minutes to 1200°C) ensure the efficiency and reliability of the porcelain process.     In addition, there are many types of porcelain furnaces, including manual, semi-automatic and fully automatic types, to meet different workflow requirements. With the application of infrared technology, the porcelain process has become more efficient, economical and environmentally friendly. The selection of porcelain furnaces needs to consider factors such as the type of porcelain, the required firing temperature, etc. to ensure the quality and effect of dental restorations.