The thermal field is the core part of the vacuum resistance furnace. Its quality directly affects the performance and operation cost of the furnace. The graphite heat field of most vacuum resistors mainly consists of four main parts: the heater and the connecting part, the heat insulation component (or the reflection screen), the heat field support component, the workpiece carrying the land bed. The main heat field is square and round. Most of these vacuum resistance furnace components are made of high purity graphite, which involves a question why use graphite material? That is because it has the advantage that graphite has other metal materials. It has characteristics of high temperature resistance, heat conduction, conductive, good, good lubrication, good plasticity, stable chemical properties, good thermal shock resistance and so on, and with the development of graphite processing technology, isostatic pressing graphite, mould press graphite, special stone. The birth of ink has made the advantages of graphite more fully utilized.
Vacuum furnace graphite heater
Most vacuum furnaces use a method of resistance heating, which mainly depends on the temperature. For low working temperatures, such as the vacuum tempering furnace, the cheap nickel chromium alloy is competent. Molybdenum and graphite electrode are the most popular materials for high-temperature heat treatments such as quenching and brazing furnaces. With the improvement of graphite material properties and processing technology, more and more graphite heaters have been applied to heat treatment and brazing furnace, which have exceeded the molybdenum heater in quantity. The main advantages of graphite heater are: lightweight design, rich shape, durable and easy to maintain.
Hot field bearing parts
Because of the high strength of the material, the molybdenum hearth can be built lighter than the graphite furnace for the same weight. In a long and warm environment, molybdenum tracks will produce some degree of deformation. Although the graphite furnace has a large weight and it has a larger thermal capacity at low temperature, the graphite furnace will not be hot, and the good thermal conductivity of graphite reduces some of its disadvantages.
Graphite heat insulation component
The current popular design is to use graphite materials to make thermal field insulation parts. The standard graphite insulation is made up of plate or multilayer carpets of graphite carbon fiber. On the inner surface near the center of the heat field, a layer of graphite paper or carbon carbon composite sheet is often needed to improve the thermal reflectivity and prevent the scour of high pressure air. Due to the porosity and permeability of graphite, there is no need to reserve additional space between the layers. Graphite materials have excellent thermal insulation properties, which are usually lower than metal screens and are very easy to use. In terms of manufacturing cost, durability and maintainability, graphite insulation felt has certain advantages over graphite heat insulation felt.