1.Product Overview

The vacuum graphite furnace is a vertical vacuum resistance furnace that uses graphite as the heating element. It features high operating temperature and excellent temperature uniformity, and is mainly used for sintering metal compounds, ceramics, inorganic compounds, nanomaterials, rare earth materials and other substances in a vacuum or protective atmosphere.

2.Product Display (for reference only)

3.Technical Parameters

Rated Power: 40KW (for reference only)

Power Supply Voltage: 380V

Heater Voltage: 0-33V (Three-phase)

Maximum Temperature: 2000℃

Operating Temperature: ≤1900℃

Working Zone Dimensions: φ160 * 160mm (Diameter*Height)

Ultimate Vacuum: 6.7 * 10-3 Pa

Operating Vacuum: 6.7 * 10-2 Pa (below 1800℃)

Temperature Measurement Method: Tungsten-Rhenium Thermocouple

Temperature Uniformity: ±5℃

Applicable Atmosphere: Nitrogen and Argon gas compatible

4.Introduction to Furnace Structure

Furnace Body Structure

The furnace body adopts a vertical shell structure. Its inner layer is a cylinder made of 304 stainless steel, while the outer shell is a carbon steel cylinder with a painted surface. A jacket is formed between the two layers, which can be connected to cooling water to remove the heat transferred to the inner wall of the furnace shell. The inner and outer cylinders are welded integrally with the upper and lower flanges, with a vacuum port, thermocouple port, gas inlet/outlet, and observation port arranged in the middle.

The upper part of the furnace body is the furnace cover, which is welded from inner/outer heads and a flange. The middle part of the cover can be connected to cooling water. A locking device is installed on the cover. After releasing the lock, the cover can be manually lifted and then pushed fully open for loading and unloading materials.

The furnace bottom consists of inner/outer heads and a flange, with cooling water passages inside. It is fixed on the support frame at the lower part of the furnace body. Electrode leads are arranged under the furnace bottom and are water-cooled to prevent seal ring melting due to excessive heat.

Furnace Lining Material

Heating Elements & Insulation Screens: The heating elements are processed into a cylindrical structure using high-purity graphite. The insulation screens consist of graphite cylinders, graphite felts, and soft carbon felts, featuring uniform heating, large radiation area, excellent thermal shock resistance, and capability for rapid heating. The entire assembly is externally supported and fixed by a stainless steel frame. The bottom insulation screen is made of graphite. All heating elements, insulation cylinders, and graphite felts are fabricated from high-purity graphite.

Vacuum System

The vacuum system consists of a mechanical pump, a diffusion pump, and vacuum valves, among other components. A digital compound vacuum gauge is adopted for vacuum measurement.

Configuration: One 2X-30 mechanical pump, one K-200 diffusion pump, one ZDF-III digital compound vacuum gauge, and one set of vacuum valves.

Electrical Control System

The system is controlled by an IGBT medium-frequency power supply. A touch screen is mounted on the cabinet, which establishes a temperature and vacuum degree database to clearly reflect the internal conditions of the furnace, featuring a neat and aesthetic appearance. The control system adopts a programmable logic controller (PLC) to realize touch screen control, and the electrical components are of the Chint brand.

The opening and closing of the mechanical pump valves are realized by a pneumatic system, ensuring simple and convenient operation.

Water Cooling System

Cooling water enters through the main pipe, is distributed via branch pipes to the furnace shell, furnace cover, furnace bottom, electrodes, diffusion pump, mechanical pump, and other components requiring cooling, and is then collected and discharged through the main return pipe. Each cooling water branch is equipped with a manual valve for flow rate adjustment as needed. An electric contact pressure gauge is installed on the water inlet pipe, which will automatically cut off the heater when the water pressure drops below 0.1 MPa.

Temperature Control Instrument

Key Features:

Equipped with AI control, it features no overshoot and self-tuning function, enabling arbitrary slope control for heating and cooling processes.

The input and output adopt a digital calibration system, ensuring accurate and stable measurement. It can be expanded to use non-linear sensors of any thermocouple or RTD type.

High measurement accuracy of Class 0.2 is achieved, maintaining precise measurement and stable operation even in high-interference environments.

Alarm functions: Upper limit alarm and input open-circuit alarm.

Disturbance-free switching between automatic and manual modes, with 30-segment program control function.

Power failure protection: EPROM chip is used to reliably store all data even when the instrument is powered off or subjected to interference.

Power supply: 85～264VAC, 50～60Hz

Power consumption: ≤5W

High-Power Transformer

The equipment power supply is stepped down by a transformer and then connected to the furnace body electrodes to supply power to the graphite heating elements. This configuration prevents arcing, which could damage the heating elements and furnace chamber, under vacuum conditions. Copper busbars are used for the connection between the transformer output terminals and the electrodes to avoid overheating due to excessive current.

Transformer selection depends on the furnace chamber size and operating temperature, and shall be determined by the design engineer in detail.

Temperature Curve Schematic Diagram

Heating Curve Test

To help you gain a clearer understanding of program editing, the curve of a 6-segment program, along with the corresponding symbols and their meanings for each segment, is listed below (for reference only):

5.Equipment Delivery Time and Warranty Plan

Payment Terms: 50% payment shall be made before production commences, and the remaining balance shall be settled in full before delivery.

Delivery Time: 70 days after receipt of the deposit.

Equipment Warranty Period: 12 months.

Free maintenance is provided within one year, and lifetime technical support is available.In the event of equipment failure, our company will provide a response within 6 hours and dispatch technical personnel to the site within 72 hours to arrange maintenance, excluding failures caused by non-product quality issues.

Consumables are not covered by the warranty, including but not limited to heating elements, fuses, and thermocouples.