Factory Price Bright Molybdenum Crucibles For Sapphire Growing Furnace - Molybdenum heat shield – WINNERS

Product Description

As the heat insulation component in the vacuum furnace, the biggest function of the heat shield is to block and reflect the heat in the furnace. Therefore, high-purity, accurate size, smooth surface, easy assembly, and reasonable design of heat shields are very important.

Molybdenum heat shields are generally produced and processed with 0.5-1.2 mm molybdenum sheets. Generally, there are 4-6 layers. The inner layer of the furnace is made of high-temperature molybdenum TZM material with a thickness of 1.2 mm. Molybdenum strips are used to separate the layers with a space of 7mm. ​Other molybdenum heat shields are made of 0.5-0.8 mm MO1 material. 

The heat shields are generally fixed by means of molybdenum bolt fastening or molybdenum sheet riveting.

Design points of metal heat shield

①Thermal properties of materials

The maximum temperature of the selected metal material should be greater than the environmental working temperature, and the thermal deformation of the metal should be small. When the temperature is higher than 900°C, tungsten, molybdenum and tantalum sheets are generally used. Below 900°C, stainless steel sheet is generally used.

②Material blackness

Choose low blackness material, surface reflection effect is better, higher surface finishes.

③Material thickness

The thickness of the heat shield should be as thin as possible. Molybdenum is generally 0.2 ~ 0.5mm. Stainless steel plate is generally 0.5 ~ 1mm.

④Material price

Under the condition that the working temperature is satisfied, the material cost should be considered, and the cheaper material should be selected.

⑤Determining the number of layers of heat shield

With the increase of the number of layers, the heat loss decreases, the cost increases, the structure is complicated, and the vacuum degree is more difficult to meet working requirements. Increasing to three layers to increase about 8%. The number of layers is not the better, and it should be considered comprehensively. The working temperature is 1000℃, and up to six layers can be used.

⑥Spacing between each heat shield

The spacing should be minimized. The thermal effect of increasing the distance is not large. If the spacing is too small, the two insulation plates will be connected together due to thermal deformation. Reduce the spacing, generally around 10mm.

⑦Connections between layers

Each layer of heat shield should be connected, and the contact area of the connection should not be too large, which will reduce the thermal efficiency. Use bushings and washers to connect each layer.

⑧Maintenance of the heat shield

The heat shield should be designed to be easily disassembled, and the thermal expansion and contraction properties of the material should also be considered.

⑨The distance between the first screen and the radiating surface

Generally 50~100mm

⑩The distance between the outermost screen and the circulating water wall

Generally 100~150mm

Note: We can provide different heat shield assembly solutions for you to choose from, achieving a good balance between practicality and economy.

▎Product Parameters

▎Order Information

Inquiries and orders should include the following information:​
☑ Drawing of the Molybdenum isolation screen
☑ Material of the screen (W, Mo, Ta or SS304)
☑ Quantity