In the high-temperature industry, pure tungsten electrodes have emerged as indispensable core materials in welding, smelting, and plasma technology, thanks to their exceptional physical and chemical properties. As the single metallic element with the highest melting point, tungsten's stability in extreme environments makes it the preferred choice for processing high-melting-point metals and demanding processes.
I. Material Characteristics of Pure Tungsten Electrodes
Pure tungsten electrodes are made from tungsten with a purity exceeding 99.95%, and their core advantages are reflected in the following aspects:
High-Temperature Stability: Tungsten has a melting point as high as 3422°C and maintains excellent mechanical strength at high temperatures, preventing the electrode from melting in the arc.
Low Vapor Pressure: At temperatures above 2000°C, tungsten's evaporation rate is extremely low, reducing electrode wear and extending its service life.
High Electron Work Function (4.55 eV): Although it requires a higher arc initiation voltage, the arc is concentrated and stable, making it suitable for precision welding.
Corrosion Resistance: Its resistance to acids, alkalis, and molten metals makes it highly favored in metallurgical and chemical industries.
Zero Radioactive Pollution: Complies with ISO 14000 environmental standards.
II. Core Application Scenarios
TIG Welding: In the welding of aluminum and magnesium alloys, pure tungsten electrodes are preferred for manufacturing food-grade equipment and medical devices due to their lack of radioactive pollution (compared to thoriated tungsten electrodes).
Plasma Cutting: When used with an argon-hydrogen mixture, it can cut 30mm thick stainless steel with an oxidation layer of only 0.1mm.
Single Crystal Silicon Growth: In the Czochralski (CZ) method single crystal furnace, pure tungsten electrodes carry a current of 3000A, ensuring stable heating of silicon melt at 1600°C.
Special Metallurgy: Used in electron beam melting furnaces for the preparation of metals like titanium and molybdenum with a purity of 99.999%.
III. Technical Challenges and Future Trends
Currently, pure tungsten electrodes face two major bottlenecks:
Difficulty in Cold-State Arc Initiation: The development of composite electrodes with surface coatings of rare earth oxides (such as La?O?) can reduce the arc initiation voltage to 60V.
Cost Control: Powder Injection Molding (PIM) technology increases raw material utilization from 70% in traditional processes to 95%.
Future development directions include:
Gradient Functional Electrodes: Surface doping with alloys or rare earth elements like rhenium (3%-5%) to enhance ductility, while maintaining high purity in the core to preserve heat resistance.
Intelligent Monitoring Systems: Integration of fiber optic sensors for real-time monitoring of electrode temperature, providing early warning of ablation risks.
