The molybdenum insulation screen is part of the thermal shielding system of the high-temperature vacuum furnace
As a core component of the thermal field materials in high-temperature vacuum furnaces, molybdenum heat insulation screens, with their high melting point, low vapor pressure and excellent high-temperature stability, have become the key to ensuring uniform thermal fields in the furnace chamber and achieving high energy efficiency.
What is a molybdenum heat shield? Core functions and definitions
A molybdenum heat shield, also known as a molybdenum thermal shield or molybdenum reflective screen, is a key component in high-temperature vacuum furnaces (vacuum sintering furnaces, vacuum heat treatment furnaces) used to create uniform hot zones and reduce heat loss. It is made by precisely processing high-purity molybdenum plates or sheets and assembling them into multi-layer cylindrical or box-shaped structures that surround the heating elements and workpieces.
Its core function is to reflect thermal radiation. In a vacuum environment, heat conduction and convection are almost non-existent, and heat is mainly transferred through radiation. The multi-layer molybdenum insulation screen effectively "locks" the heat within the working area of the furnace by reflecting the radiant energy, thereby significantly enhancing the heating efficiency and reducing energy consumption.
Why choose molybdenum? The outstanding material properties of molybdenum heat shields
Molybdenum metal is the ideal refractory metal material for manufacturing high-end heat shields due to its series of irreplaceable physical and chemical properties:
Extremely high melting point: Molybdenum has a melting point as high as 2620°C, enabling it to operate stably for a long time in typical high-temperature processes ranging from 1600°C to 1800°C without softening or deforming.
Low vapor pressure and high vacuum stability: In high-temperature vacuum environments, the evaporation rate of molybdenum is extremely low, effectively preventing contamination within the furnace and avoiding volatile contaminants from affecting the purity and performance of workpieces (such as semiconductor components and advanced alloys). This is crucial for high-quality sintering processes.
Outstanding high-temperature strength and creep resistance: Molybdenum can maintain high mechanical strength at high temperatures. Its high-temperature structural stability ensures that the multi-layer insulation screen will not collapse or deform during long-term thermal cycling, thus extending its service life.
Good thermal radiation reflectivity: The surface of molybdenum metal can effectively reflect infrared radiation, which is the basis for its use as an efficient reflector screen.
Technical Deep Dive: Structural Design and Manufacturing Process of Molybdenum Thermal Insulation Screens
Mainstream Structures: All-Molybdenum Screens and Molybdenum-Stainless Steel Composite Screens
All-Molybdenum Thermal Insulation Screens: Composed of multiple layers of pure molybdenum plates (common thickness: 0.2mm - 1.0mm). This structure offers the best performance and is used in the highest temperature (>1800°C) and cleanest process environments, but it also has the highest cost.
Inner molybdenum and outer steel composite screen: Only 1-2 layers of molybdenum screens are used on the inner side of the high-temperature zone, while the outer side adopts stainless steel insulation screens with better cost performance. This design ensures the performance of the core heat zone while significantly reducing manufacturing costs, and is a common configuration in many industrial furnaces.
Key manufacturing and processing technologies
Deep processing of molybdenum plates: Involves processes such as stamping, bending, and welding (molybdenum tungsten inert gas welding), which places extremely high demands on the manufacturer's processing capabilities.
Surface treatment: In some applications, the molybdenum screen undergoes surface polishing to further enhance its thermal reflection efficiency.
For processes involving high-end magnetic materials, aerospace alloys, special ceramics, and semiconductor materials where carbon contamination is strictly prohibited, molybdenum heat shields are the undisputed best choice. Graphite heat shields, on the other hand, are more commonly used in applications where carbon contamination is not a concern or where budgets are limited.
Application fields: In which industries is molybdenum insulation screen technology relied upon?
Powder metallurgy and hard alloy sintering: It is used in the sintering of tungsten carbide, metal ceramics, etc., to prevent carbon from getting out of control.
Aerospace high-temperature alloy heat treatment: Vacuum solution treatment and aging treatment for nickel-based and cobalt-based superalloys.
Sintering of rare earth permanent magnetic materials: Sintering and tempering of magnets such as neodymium iron boron and samarium cobalt, with extremely high requirements for the cleanliness inside the furnace.
Photovoltaic and semiconductor industries: Thermal field components for monocrystalline silicon growth furnaces and semiconductor diffusion furnaces.
To maintain and extend the service life of molybdenum heat shields and ensure their long-term performance, the following points should be noted:
Prevent oxidation: It is strictly forbidden to introduce air at high temperatures. When loading the furnace, avoid contact with oxygen-containing substances.
Regular inspection: Check for mechanical damage or loose connections.
Professional cleaning: After use, gently wipe with alcohol or acetone to remove minor contaminants.
Molybdenum heat shield is in demand in various parts of the world, such as the USA, Canada, Chile, Brazil, Argentina, Colombia, Germany, France, the United Kingdom, Italy, Sweden, Austria, the Netherlands, Belgium, Switzerland, Spain, the Czech Republic, and Poland.
Mosten Alloy can produce and supply molybdenum heat shield, molybdenum pellet, molybdenum target, molybdenum sheet, molybdenum block, molybdenum foil, molybdenum wire, molybdenum rod, molybdenum processing workpiece according to customer demand.
