ZHENGZHOU SONGYU HIGH TEMPERATURE TECHNOLOGY CO.,LTD

Advantages of SiC heating elements in industrial applications

Silicon carbide (SiC) heating elements are increasingly popular in industrial applications due to their superior thermal and electrical properties. These elements are primarily used for high-temperature heating in various fields, including manufacturing, ceramics, and metalworking. Understanding the characteristics and benefits of SiC heating elements is crucial for professionals seeking to improve the efficiency and reliability of their heating processes.   One of the most significant advantages of SiC heating elements is their ability to operate at high temperatures, often exceeding 1,600°C (2,912°F). This high-temperature capability makes them ideal for demanding applications requiring stable and reliable heating, such as sintering ceramics or melting metals. Unlike traditional heating elements, SiC heating elements can withstand these high temperatures without performance degradation over time, extending their service life and reducing maintenance costs.   Furthermore, SiC heating elements are known for their excellent thermal conductivity, enabling rapid heating and cooling cycles. This characteristic not only improves the efficiency of the heating process but also contributes to energy savings. Because SiC elements can quickly reach operating temperature, downtime can be minimized and production schedules optimized, which is crucial in fast-paced manufacturing environments.   Another significant advantage of SiC heating elements is their resistance to oxidation and corrosion. Unlike traditional materials that can degrade when exposed to harsh environments, SiC remains stable and reliable even in corrosive environments. This property makes it an ideal choice for industries working with reactive or corrosive materials, ensuring that heating elements do not compromise process or product quality.   Furthermore, SiC heating elements can be designed into a variety of shapes and configurations to meet specific needs. Whether in rod, plate, or custom form, their versatility enables integration into a wide range of heating systems. This adaptability is a significant advantage for engineers and designers who require customized solutions to address unique heating challenges.   In summary, SiC heating elements offer a variety of advantages that make them a top choice for industrial heating applications. Their high-temperature performance, excellent thermal conductivity, corrosion resistance, and flexible design provide a comprehensive solution for improving the efficiency and reliability of heating processes. As industries across the board continuously seek ways to improve their operations, adopting silicon carbide heating elements can significantly enhance performance and cost-effectiveness. Understanding these advantages allows professionals to make informed decisions, enhance operational capabilities, and achieve success in their respective fields.

The "Heart" of Industrial Furnaces Revealed: Silicon Carbon Rods vs. Silicon Molybdenum Rods: How to Choose a High-Temperature Heating Element?

In industries like metallurgy, ceramics, and semiconductors, industrial furnaces are core equipment for thermal processing of materials, and heating elements are the heart of these furnaces, determining their heating capacity. Silicon carbide rods and silicon molybdenum rods, due to their high-temperature resistance and stability, are the mainstream choice for applications in the 1200-1800°C temperature range. However, their applications differ significantly, and choosing the right element is crucial for efficient furnace operation. The following details the key differences and selection logic between the two. 1. Core Material and High-Temperature Resistance: From "Basic Tolerance" to "High-Temperature Limits" The performance differences between silicon carbide rods and silicon molybdenum rods stem from their core materials: Silicon carbide rods are made from high-purity silicon carbide (SiC) and are recrystallized and sintered at 2200°C. Their normal operating temperature range is 1200-1600°C, with a short-term maximum operating temperature of 1650°C. Their material properties ensure they maintain excellent mechanical strength even at high temperatures, require no protective atmosphere when used in air, and exhibit stable oxidation resistance. Silicon-molybdenum rods: Made of molybdenum silicide (MoSi₂), a composite of molybdenum (Mo) and silicon (Si), they are sintered at high temperatures and have a wider operating temperature range, reaching 1600-1800°C, with a short-term maximum temperature exceeding 1850°C. However, it should be noted that silicon-molybdenum rods are susceptible to "low-temperature oxidation" (forming MoO₃, which causes material embrittlement) in the 500-800°C range. Therefore, during startup, the temperature must be raised quickly to exceed this range, or protective measures must be implemented. 2.Core Selection Logic: Matching "Temperature Requirements" with "Process Scenario" In actual production, there's no need to blindly pursue "higher temperatures." Instead, consider the core requirements of industrial furnaces when selecting a model: Silicon Carbide Rods: For process temperatures between 1200-1500°C (such as ceramic body sintering, ordinary metal tempering, and glass annealing), and for high cost-effectiveness and ease of maintenance, silicon carbide rods are the optimal choice. For example, tunnel kilns in household ceramic factories and small heat treatment furnaces in hardware factories often use silicon carbide rods as heating elements. Silicon Molybdenum Rods: For process temperatures exceeding 1600°C (such as precision ceramic sintering, heat treatment of specialty metals (titanium alloys, high-temperature alloys), and high-temperature synthesis of semiconductor materials), or when extremely high heating rates and temperature control accuracy are required, silicon molybdenum rods are more suitable. For example, heat treatment furnaces for high-temperature alloy components in the aerospace industry and precision high-temperature sintering furnaces in laboratories all use silicon molybdenum rods as core heating elements. 3. Usage Tips: Key Details for Extending Heating Element Life Regardless of the element chosen, proper use can significantly extend its lifespan: Avoid "dry firing": Before starting an industrial furnace, ensure that heated material or a protective atmosphere is present in the furnace chamber to prevent the elements from being exposed to the high temperatures of an empty furnace, which accelerates aging. Stable Temperature Control: Avoid frequent starts and stops or rapid temperature increases and decreases, especially for silicon-molybdenum rods, which must quickly pass through the low-temperature oxidation zone of 500-800°C. Regular Inspection: During daily production, carefully inspect the element surface for cracks and deformation. If damaged, replace it promptly to avoid affecting overall heating efficiency. As the "core power source" of industrial furnaces, silicon-carbon rods and silicon-molybdenum rods, while seemingly compact, are directly related to production efficiency and product quality. Understanding their characteristics and selection principles can ensure that industrial furnaces perform precisely during high-temperature operations, safeguarding the thermal processing processes of various industries.

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.