Customized Solution For Molybdenum Metal Bar: Tolerance Standards And Purity Testing Methods
Molybdenum metal bars are used in fields such as high temperature furnaces, semiconductor equipment, aerospace, and medical imaging. Molybdenum has a melting point of 2620 ° C. It has good strength at high temperatures, good creep resistance, good thermal conductivity and corrosion resistance, so it is more suitable under extreme conditions. When purchasing molybdenum metal rods, buyers usually care about two issues: Can the size tolerance comply with the drawings? Is the purity up to standard? The following describes the main uses, tolerance standards, purity testing methods, and some issues that need to be paid attention to when purchasing molybdenum metal rods.
1. Main Uses Of Molybdenum Metal Rods
The application of molybdenum metal bar is mainly based on its several characteristics: high melting point, good strength at high temperatures, good thermal and electrical conductivity, and corrosion resistance. The main uses are these.
1. Make deep processing raw materials
This is the most basic and large-scale use of molybdenum metal rods. It is a semi-finished product and will be processed into downstream products such as molybdenum wire and molybdenum plate. Molybdenum wire can be used as filament brackets for incandescent lamps, furnace wires for high-temperature furnaces, and wire cut electrode wires. Molybdenum plates can be used as hot field parts of sapphire crystal growth furnaces, heating bodies of vacuum furnaces, and sputtering targets.
2. Making high-temperature structural parts
After direct processing, support parts and connections at high temperatures are made, such as support rods for sintering furnaces and electrodes for glass melting furnaces.
3. Making high-temperature fasteners
In a high temperature environment protected by vacuum or inert gas, ordinary steel will soften, rust, and volatilize, and molybdenum has better high temperature resistance. Molybdenum screws, molybdenum nuts, and molybdenum bolts are used in high-temperature furnace assembly to help ensure the stability of equipment under extreme conditions.
4. Semiconductor and medical fields
High-purity molybdenum metal rods can be used on fixtures, electrodes and structural parts of semiconductor equipment. Liquid metal bearings in high-power X-ray tubes have certain requirements on the density and grain size of molybdenum rods.
2. Tolerance Standards
size accuracy is a more important clause in the purchase contract. Unqualified size may affect assembly or equipment operation. The international production of molybdenum metal rods is usually done in accordance with the ASTM B387 standard.
The ASTM B387 standard has corresponding regulations on allowable deviations for molybdenum rods of different diameters:
| Diameter Range (mm) | Tolerance (mm) | Note |
| Micro Rods (< 1.59) | ±0.01 ~ ±0.03 | Centerless ground |
| 0.51 - 1.59 | ±0.03 | Ovality ≤ 0.03 |
| 1.59 - 3.18 | ±0.05 | Ovality ≤ 0.05 |
| 3.18 - 7.14 | ±0.10 | Ovality ≤ 0.10 |
| 7.14 - 15.9 | ±0.20 | Ovality ≤ 0.25 |
| 15.9 - 34.9 | ±0.30 | Ovality ≤ 0.43 |
| 34.9 - 50.8 | ±0.46 | Ovality ≤ 0.58 |
| 50.8 - 84.1 | ±0.81 | Ovality ≤ 0.66 |
| 84.1 - 120.7 | ±1.02 | Ovality ≤ 0.71 |
| > 120.7 | ±1.50 | Ovality ≤ 0.76 |
Diameter tolerance and ovality tolerance are two key indicators that need to be confirmed when purchasing. Different application scenarios have different requirements for these indicators. For example, molybdenum rods used in precision semiconductor equipment usually have stricter tolerance requirements than ordinary high-temperature furnace parts.
Liaoning Hongtuo New Material Technology Co., Ltd. has accumulated a lot of experience in production practice. Their molybdenum metal bar can be made from 3mm to 152mm (6.0 inches) in diameter and up to 8 meters (26 feet) in length. If the buyer has special accuracy requirements, the diameter tolerance can be controlled to ±0.01mm. Before leaving the factory, each molybdenum rod will be inspected for its size, appearance and defects in accordance with ASTM B387 standard.
In terms of surface state, Liaoning Hongtuo offers three options:
· Black skin: There is a layer of oxide scale on the surface. After purchasing it, the buyer can handle it as needed.
· Pickling: The oxide scale has been removed and the surface is cleaner
· Careless polishing: bright surface, roughness Ra≤0.8μm
3. Purity Testing Methods
High-purity molybdenum metal rods require molybdenum content ≥99.95%. When purchasing, you can ask the supplier if you can provide traceable test reports.
1. chemical composition analysis
The purity test of molybdenum rods mainly relies on chemical composition analysis. Currently, the widely used method in the industry is inductively coupled plasma mass spectrometry (ICP-MS), which can simultaneously detect multiple impurity elements. It should be noted that when the concentration of molybdenum is high, the trace impurity signal may be suppressed, thus affecting accuracy. On-line spiking ICP-MS method is an improvement for this.
Other testing methods include:
1. Carbon and sulfur analyzer and oxygen and nitrogen analyzer: used to detect the content of non-metallic impurities such as carbon, nitrogen and oxygen
2. Ultrasonic flaw detection: Inspection before leaving the factory can help detect internal defects
2. Physical performance testing
In addition to chemical composition, buyers can also pay attention to the following physical indicators:
1. Density: sintered state ≥9.5g/cm³, forged state ≥10.1g/cm³
2. Grain size: There are certain requirements for high-end applications
In terms of testing, Liaoning Hongtuo New Material Technology Co., Ltd. will conduct cross-batch testing to ensure the stability of different batches of molybdenum rods in terms of alloy elements and microstructure. Each batch of products can be provided with a material certificate (MTC), or a third-party test report can be provided according to the purchaser's requirements.
4. Several Issues That Need To Be Paid Attention To When Purchasing
1. Confirm specific brands and standards
The purchase order only says "high-purity molybdenum rod" and has no clear brand name. Different suppliers may have different definitions of "high purity", the actual purity of materials may vary, and the performance at high temperatures may also vary. It is recommended to clearly implement standards (such as ASTM B387) in the contract and require each batch of products to provide corresponding purity test reports.
2. Focus on impurity types rather than just purity numbers
Only focus on the number "molybdenum content ≥99.95%". The content of interstitial elements such as carbon, nitrogen and oxygen has an influence on the plastic-brittle transition temperature of molybdenum rods. Different application scenarios have different requirements for specific impurities. It is recommended to understand the upper limit values of various impurities, especially the contents of carbon, nitrogen, and oxygen, and you can ask suppliers to provide a complete elemental analysis table.
3. Verify density after arrival
If there is slight porosity or incomplete densification inside the material, the density may be low. In application scenarios with high thermal conductivity and high load bearing, this may bring certain use risks. After arrival, the Archimedes drainage method can be used for density verification, or the supplier can be required to provide a third-party test report.
4. Select surface state based on use environment
In hot field applications where cleanliness requirements are high, if black skin rods with oxide scales are used, the oxide scale peeling may contaminate the vacuum chamber or affect the adhesion of subsequent coatings. It is recommended to explain the specific use environment and requirements to the supplier.
5. Distinguish melting point and safe working temperature
Molybdenum in the temperature range of 600-800℃ will begin to oxidize if it is in an oxygen-containing environment. Directly equating the melting point to the safe working temperature may lead to rapid material failure. It is recommended to clarify the atmosphere and temperature range of the use environment. If the working temperature exceeds 1000 ° C and in an aerobic atmosphere, coating protection or molybdenum alloy (such as TZM) should be considered.
5. About Liaoning Hongtuo New Materials Technology Co., Ltd.
Liaoning Hongtuo New Material Technology Co., Ltd. is a molybdenum metal products manufacturer located at No. 52, Zhongxin Road, Taihe District, Jinzhou City, Liaoning Province, China. The factory covers an area of 66,700 square meters, and the first phase construction area is 28,500 square meters.
The company is mainly engaged in the production and deep processing of molybdenum metal products, including molybdenum metal bar, ferromolybdenum, molybdenum powder, molybdenum oxide, etc. In terms of molybdenum metal rods, we can supply a variety of materials such as pure molybdenum rods (molybdenum content ≥99.95%, some can reach 99.99%), TZM alloy rods and molybdenum lanthanum alloy rods. The shapes of the rods include round and square, and the size can be customized according to the buyer's needs.
Liaoning Hongtuo has an independent processing and sintering workshop that can meet the special needs of buyers in terms of size and processing. Molybdenum rods of regular size are in stock, and non-standard customization is generally completed within 2-4 weeks. The products are tested for size, appearance and defects before leaving the factory, and a traceable material certificate is provided. In terms of transportation, customized wooden boxes and soft packaging are used to fix them to reduce collisions and displacements during transportation.
If you need more customization solutions for molybdenum metal rod products of Liaoning Hongtuo New Material Technology Co., Ltd., please contact us for consultation.
