The molybdenum heat shield is the core technology for thermal management in high-temperature vacuum systems
In modern high-temperature industrial equipment, the molybdenum heat insulation cover is a key component for creating an efficient and stable thermal environment. Especially in high-end devices such as sapphire crystal growth furnaces, rare earth smelting furnaces, and semiconductor sintering furnaces, it forms a radiation shielding system with excellent insulation and temperature control properties through the precise combination of multiple layers of molybdenum sheets and molybdenum foils. The molybdenum heat shield cover can withstand temperatures above 1800℃ and maintain structural integrity and chemical inertness in vacuum or inert atmospheres, serving as the fundamental guarantee for achieving high-quality crystal growth and high-purity material melting.
The molybdenum heat shield cover is usually composed of 3 to 6 layers of high-purity molybdenum sheets alternately arranged with ultra-thin molybdenum foils. Each layer of molybdenum sheet is precisely formed by stamping or spinning, and its surface is electrochemically polished to a smoothness of Ra ≤ 0.4 μm to maximize the thermal radiation reflectivity; the interlayer maintains a high vacuum state, effectively suppressing gas convection and conductive heat dissipation. Experiments have shown that this multi-layer structure can reduce the system's heat loss by more than 60%, while achieving a temperature difference control within ±5°C inside the furnace, meeting the strict uniform temperature requirements for single crystal material growth.
The traditional molybdenum heat shield cover is made of pure molybdenum sheet (Mo ≥ 99.95%). It achieves high-temperature bearing by relying on the high melting point (2620℃) and low thermal expansion coefficient of molybdenum. In recent years, the molybdenum-lanthanum alloy (Mo-La₂O₃) formed by doping lanthanum oxide (La₂O₃) has significantly improved the recrystallization temperature and creep resistance. For example, the strengthened molybdenum alloy heat insulation cover developed by Rizhui Research has a creep life of over 1000 hours at 1800℃, which is 150% higher than that of traditional materials, while maintaining excellent radiation reflection properties and thermal shock resistance.
The manufacturing of the molybdenum heat shield cover involves three core processes: isostatic pressing, vacuum electron beam welding, and surface treatment. The isostatic pressing technology ensures that the density of the molybdenum sheet is greater than 10.2g/cm³, effectively eliminating internal pores; the electron beam welding achieves a high-strength seamless connection between the molybdenum sheet and the supporting structure, with the weld strength reaching over 98% of the base material, completely eliminating the risk of heat leakage at high temperatures. The precise assembly of ultra-thin molybdenum foil (with a thickness of up to 0.05mm) further optimizes the lightweight and flexibility of the insulation layer, meeting the requirements of complex thermal field shapes.
In addition to basic insulation, the molybdenum insulation cover can also achieve multi-functional integration through structural design. For example, in nuclear material processing equipment, the insulation cover with tungsten-molybdenum alloy coating not only has neutron shielding properties but also supports rapid cooling at a rate of 50°C/min, significantly improving the process cycle efficiency. In corrosive molten salt environments, the surface of the molybdenum sheet can be coated with an aluminum oxide layer by plasma spraying, enabling it to remain stable in fluoride molten salt for a long time.
In the vacuum crystal growth furnace, the molybdenum insulation cover, molybdenum heating belt, and molybdenum heat field barrel jointly form a precise thermal management system. The gradient opening structure on its wall surface can guide the thermal flow to circulate in a directed manner, and in combination with the Joule heat output of the molybdenum belt, it achieves the maximum efficiency of the heat field. Especially during the growth of sapphire crystals, this component ensures the uniformity of the temperature of the alumina melt and the control of oxygen content (less than 1 ppm), directly influencing the transparency and mechanical properties of the single crystal.
With the rising demands for ultra-high temperatures (>2000°C) and extremely long-term thermal stability in fields such as the fourth-generation semiconductors and new nuclear energy materials, molybdenum heat shields are evolving towards composite coatings, intelligent thermal control, and integrated cooling structures. Innovations like nano-yttria coatings and fiber-reinforced molybdenum-based composites will further enhance their lifespan and energy efficiency performance under extreme conditions, continuously supporting the thermal management revolution in high-end manufacturing.
Molybdenum sheets are demanded in various parts of the world, such as: USA, Canada, Chile, Brazil, Argentina, Colombia, Germany, France, United Kingdom, Italy, Sweden, Austria, Netherlands, Belgium, Switzerland, Spain, Czech Republic, Poland.
As professional Chinese manufacturer, Mosten Alloy can produce and supply molybdenum electrode, molybdenum strip, molybdenum sheet, molybdenum pellet, molybdenum block, molybdenum tube, molybdenum rod, molybdenum wire, molybdenum processing workpiece according to customer demand.
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