Graphite Heater

Graphite heating elements generally include (graphite material) pressure rings, insulation covers, upper, middle and lower insulation covers, graphite crucibles (three-flap crucibles), crucible support rods, crucible trays, electrodes, heaters, guide tubes, graphite bolts, and for to prevent silicon leakage, the furnace bottom, metal electrodes, and supporting rods are all equipped with protective plates and protective covers.

The single crystal furnace graphite heating element is simply a complete graphite heating system used to pull single crystal silicon. The common ones are 18-inch, 22-inch and 24-inch graphite thermal fields. A popular industry-standard design option for graphite heating elements is to use graphite material for the heating element insulation. Standard graphite insulation materials are composed of graphitized carbon fiber materials in the form of plates or multi-layer blankets. The inner surface near the center of the heating element often needs to be covered with a layer of graphite paper or a carbon-carbon composite sheet to increase heat reflectivity and prevent high pressure. Washing by airflow.

Due to the porosity and permeability of the isostatically pressed graphite heating element material itself, no additional space is required between each layer of insulation material. Graphite materials have excellent thermal insulation properties, are generally less expensive than metal screens, and are very easy to use. In terms of manufacturing cost, durability and maintainability, graphite insulation soft felt has certain advantages over graphite insulation hard felt. Through production practice, metal heat shields are often not suitable for vacuum brazing processes in harsh environments.

Graphite heating element manufacturers use graphite materials to make insulation components for graphite thermal fields. Practice has proven that although a lot of solder is deposited on the surface of the graphite insulation material during the brazing process, the melted solder and graphite insulation will not occur. The fusion phenomenon of materials. Although some people may question that graphite materials absorb moisture more easily than metal materials, and moisture is very harmful to the brazing process, practice has proven that the repeated heating and cooling of the heating element can effectively eliminate moisture in the graphite insulation material.

The first regular maintenance item to keep your graphite heater running efficiently is to remove contaminants from within the hot zone by running a cleanup cycle. This procedure is one of several preventative steps that helps maintain the overall health of your furnace.

Another maintenance item that you can perform on a schedule to extend the life of your hot zone is inspection of the heating elements. Heating elements are key in efficient operation of your furnace, so you should visually inspect the condition of the heating elements and shields on a regular basis. As you inspect these components, look especially for broken or missing pieces or loose connectors. Any element in poor condition can lead to uneven heating cycles which, in turn, can lead to loss of productivity. If you discover graphite components are missing or damaged, replace them immediately.

Keeping in stock some common hot zone components, including heating elements, posts, bolts, nuts, nozzles, etc. If you have these extra components handy, you’re more likely to replace them immediately rather than letting the hot zone run under suboptimal conditions. With your hot zone and all of its components in good working condition, temperature uniformity is more easily achieved.

An easy but important maintenance item is to perform a daily check of the heating elements and shields for signs of discoloration. Discoloration in the furnace indicates contamination. If parts of the hot zone begin to show signs of discoloration, it could be a sign that oxygen is not getting in. A leak check should provide clues to where the leak is occurring. Without a diagnostic to identify and fix the leak, the graphite will keep degrading in the oxygen environment at temperatures around 700 f. Eventually, the graphite components in the hot zone will experience premature failure. Daily inspection for discoloration can eliminate this risk from oxidation.

Lastly, you will want to prevent arcing by hand-tightening nuts, bolts, and element connectors inside the furnace. This maintenance item should be performed on a weekly basis. When parts become loose, they can cause arcing, which then burns away the hot zone’s insulation, affects the overall quality of the heating elements, and can lead to discoloration. Hand-tightening is the recommended method so as to avoid over-tightening and breaking of graphite heating elements.

These recommendations are all small but important things you can do to greatly extend the life of your graphite heater. Create a maintenance schedule and stick to it. It will yield cycle efficiencies and, ultimately, bottom line savings in the long run.