Molybdenum Mo Heat Shield in Vacuum Furnace Mo Screen

Molybdenum and graphite are also used for vacuum-furnace insulation. In an all-metal hot-zone, the heat-shield package is made up of multiple layers of sheet metal with spaces between each layer. In a standard furnace with a maximum 1315°C (2400°F) operating temperature, the heat shielding often consists of two layers of molybdenum sheet backed by three layers of stainless steel sheet. For higher operating temperatures, the number of molybdenum layers is increased as well as the thickness of each layer. For very high operating temperatures over 1650°C (3000°F), tantalum sheet can be used in place of molybdenum. The insulating properties of the all-metal design come mostly from the gaps between the layers of sheet metal. These gaps prevent heat from being conducted outward from the hot zone. The reflectivity of the inner molybdenum sheet also helps to direct the radiant heat from the elements inward toward the load. All-metal hot zones tend to be preferred when high-vacuum or very clean processing environments are required (medical-component processing). Care must be taken in operating furnaces with all-metal hot zones because molybdenum embrittles due to recrystallization after a single exposure to temperatures above about 1150°C (2100°F). Embrittled heat shields can be relatively easily damaged if struck by fixtures or parts.

A heating element converts electricity into heat. Electric current passing through the element encounters resistance, resulting in heating of the element and the high temperatures in the vacuum furnace.

Heating element is one of the most important parts in vacuum furnace hot zone construction. We supplies heating elements made of molybdenum, tungsten, tantalum, niobium and their alloys.