Second - hand vacuum furnace why to use tungsten insulation screen?
Second-hand vacuum furnace, that is, in the furnace chamber this specific space in the use of vacuum system will be part of the furnace chamber material discharge, so that the pressure in the furnace chamber is less than a standard atmospheric pressure, the space in the furnace chamber to achieve a vacuum state of mechanical equipment. So, we know why the vacuum furnace to use tungsten insulation screen specific reasons are what?
1. Tungsten is a refractory metal, with high melting point (3410℃), high density (19.35g/cm3), high hardness, high strength, low thermal expansion coefficient, good heat resistance, good corrosion resistance, so it can make the production of heat insulation parts of the overall performance is better, mainly in the heat resistance effect is good, strong heat resistance, long service life, Even in thousands of degrees Celsius environment, the component is not easy to appear deformation.
2. Molybdenum heat shield or tungsten heat insulation screen is generally made by riveting, which can be butt joint or lap joint. Between each layer of screen can be separated by corrugated plate, U type grid or ring, and fixed with molybdenum wire or tungsten wire and screws. It is important to note that tungsten oxidizes rapidly at temperatures above 500℃ in air, and molybdenum oxidizes at temperatures above 400℃, so molybdenum and tungsten components should be used in a vacuum or inert atmosphere.
3. The side screen and upper and lower cover screen of the vacuum furnace can be made with molybdenum insulation screen, but also can be produced with tungsten insulation screen. Components made of tungsten and molybdenum provide better thermal insulation and better insulation against heat convection than components made of other materials.
4. Molybdenum is also a refractory metal, with a density of 10.23g/cm3, about half of tungsten metal, with high melting point (2622℃), high hardness, very low thermal expansion coefficient and resistivity and other characteristics, so it is often used to produce thermal insulation parts that work in high temperature environment for a long time.
