Standardization of molybdenum wire
Molybdenum wire has high melting point, high strength and elastic modulus, small expansion coefficient, low vapor pressure, good electrical and thermal conductivity and excellent corrosion resistance. It is widely used in lighting appliances, vacuum electronic devices machining, spraying and other fields. The standard of molybdenum wire formulates the criterion of production and use of molybdenum wire, which represents the technical level of molybdenum wire production. In order to meet the needs of scientific development and reasonable production organization, standardization is to provide unified technical standards in terms of product quality, variety specifications, and general parts. With the rapid development of global integration of technology and economy, especially after China's entry into WTO, the requirement of product internationalization is higher and higher. Therefore, the study of molybdenum wire standardization has important practical significance.
China's molybdenum wire standard began in 1972, first issued the ministry standard: SJ316 molybdenum wire, 12 years later issued the national standard: GB4182 molybdenum wire. 15 years later, the national standard was revised and issued GB / T4182 molybdenum wire. The current standard was GB / T4182 molybdenum wire. Last year, the current national standard was revised and GB / T4182-200x molybdenum wire (Draft for approval).
American molybdenum wire standard has two standards: thick wire and fine wire: ASTM F289 and ASTM B 387. ASTM F 289 Tstandard began in 1954. ASTM b289-54T was first formulated and issued. Two years later, ASTM F 289 was re issued. After 25 years, ASTM F 289 was revised and issued 15 years later, ASTM F 289 was revised and issued. The current standard is ASTM F 289. ASTM B 387 standard began in 1962. The first one was ASTM B687-62T. It was revised 23 years later and issued ASTM B 387-85. Five years later, it was revised and issued ASTM B 387. The current standard is ASTM B 387(2001).
The standard of molybdenum wire in Japan began in 1976. JISH 4481 was first formulated and issued. After 13 years, JIS H4481 was revised and issued. The current standard is JIS H4481.
According to the application industry, the scope of application of molybdenum wire is "this standard is applicable to lighting appliances, vacuum electronic devices, machining, spraying and other molybdenum wires". In the original standard (GB / T4182), the names of electric light source components (such as hook, grid wire, etc.) are deleted; spraying is added; and machining is replaced by wire cutting.
The United States and Japan have formulated separate standards for pure molybdenum wires used in electronic devices and lighting, such as ASTM F289, JIS H4481, and some standards for molybdenum wires, such as ASTM B387(Reapproved 2001), JIS H 4471.
There are many brands of molybdenum alloys, and the international standardized ones are Mo30W, Mo50W and TZM. Mola and MoY, which have been industrialized and applied, are waiting for international standardization. The technical level of MoLa Mo Y molybdenum alloy wire in China has reached the international advanced level, so it is urgent to take the lead in the international standardization. However, there is a lack of analytical methods for Ti, Zr, La, Y and other elements in molybdenum alloys and testing methods for high temperature properties of molybdenum alloys, so it is impossible to formulate the standards for TZM, Mola and Moy molybdenum alloy wires in China.
China has formulated GB / T4183 for Mo30W and Mo50W molybdenum alloy wires, and national standards for TZM, Mola and MoY should also be formulated separately.
In the original standard (GB / T4182), Mol and Mo2 are pure molybdenum wire grades. In the production process, the molybdenum powder of Mo2 is slightly coarser than that of Mol. The thickness of molybdenum powder is not the only quality index of molybdenum powder, nor does it determine the quality of molybdenum wire, and it lacks operability in the standard of molybdenum wire. In the standard, M3 (M1 (, M3 g) represents the added elements, but the name and specific content of the added elements are not given in the chemical composition. (for extended type, G for high temperature requirement type. The corresponding indexes of tensile strength and elongation are not given in the performance requirements.
According to the international practice and the frame of the national standard of molybdenum and molybdenum alloy wire formed in China, only pure molybdenum grade is set in the new standard.
