Low Oxygen Molybdenum Powder via Two-Step Calcium Reduction
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Solution Overview
Problem
Current methods for producing molybdenum powders from molybdenum trioxide result in high oxygen content, leading to contamination and reduced density, and struggle to achieve fine particle sizes with low oxygen content.
Innovation Solution
A method involving a two-step reduction process using calcium powders, where the first reduction occurs at 550-650°C and the second at 1000-1200°C, with specific weight ratios and particle size differences between calcium granules, to produce molybdenum powders with oxygen content below 3,000 ppm and particle sizes of 5 μm or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If hydrogen atmosphere reduction is used to obtain molybdenum, then the reduction process is simple, but high oxygen content remains in the reduced molybdenum powders
Solution Approach 1:
The invention changes the chemical environment parameters by replacing hydrogen atmosphere with a vacuum environment and introducing calcium as a reducing agent. This parameter change transforms the reduction mechanism from hydrogen-based to calcium-based, enabling oxygen removal while preventing oxygen re-contamination during the reduction process.
Solution Approach 2:
The invention creates an inert environment by performing the reduction process under vacuum conditions. This inert environment prevents oxygen from re-contaminating the molybdenum powder during reduction, thereby achieving low oxygen content in the final product while maintaining process simplicity.
2Object-affected harmful factors
If metal representing oxygen reduction reaction superior to molybdenum is used, then oxygen content is reduced, but contamination occurs due to metal mixing and retrieval becomes difficult
Solution Approach 1:
The invention extracts the oxygen from molybdenum trioxide by using calcium as a selective oxygen scavenger. The calcium reacts with oxygen to form calcium oxide, which can be easily separated from the molybdenum powder through size difference and density separation, thereby removing oxygen contamination without introducing difficult-to-retrieve metal contamination.
Solution Approach 2:
The invention uses calcium with specifically controlled particle sizes (larger than molybdenum trioxide particles) to ensure that after reduction, the calcium oxide byproduct can be easily separated from the fine molybdenum powder. This local quality control of particle size enables selective separation and prevents contamination issues.
3Productivity
If particle size of molybdenum powders is reduced to increase reaction activity, then reaction activity increases, but obtaining low oxygen content becomes difficult
Solution Approach 1:
The invention performs preliminary action by pre-mixing calcium powder with molybdenum trioxide in specific weight ratios before reduction. This pre-mixed configuration ensures that calcium is already in contact with molybdenum trioxide particles, enabling efficient oxygen removal during reduction while maintaining fine particle size and high reaction activity in the final product.
Solution Approach 2:
The invention creates a composite mixture of calcium and molybdenum trioxide with specific weight ratios (calcium: molybdenum trioxide = 1:2 to 3:2 by weight) before reduction. This composite structure ensures uniform distribution of calcium throughout the molybdenum trioxide, enabling thorough oxygen removal while maintaining fine particle size and high reaction activity.
4Strength
If high-melting point metal including molybdenum is used, then superior physical and mechanical characteristics are achieved, but high affinity with oxygen and gas impurities causes easy contamination
Solution Approach 1:
The invention performs the reduction process under vacuum conditions to create an inert environment that prevents oxygen and gas impurities from contaminating the high-melting point molybdenum metal. This inert environment protects the superior physical and mechanical characteristics of molybdenum while preventing oxidation and gas impurity absorption during processing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively reduces oxygen content and achieves fine, dense molybdenum powders with enhanced reaction activity, improving sinterability and reducing contamination.
Implementation Method 1
a method of producing low oxygen-content molybdenum powders by reducing molybdenum trioxide
Implementation Method 2
the reduction to metal molybdenum (Mo) from MoO3 is performed by removing oxygen
Implementation Method 3
performing a reduction reaction by raising an internal temperature of the body
Data Source
AI summary
Disclosed is a method of producing low oxygen-content molybdenum powders by reducing molybdenum trioxide, which includes charging a first reducing agent and the molybdenum trioxide, which are in the direct contact with each other on a micro-sieve on an upper portion of a bracket in a body, charging a second reducing agent in the bracket under the micro-sieve, coupling the body with a cover to close the body, and performing a reduction reaction by raising an internal temperature of the body by performing the first reduction reaction due to direct contact between the first reducing agent and the molybdenum trioxide, and performing the second reduction reaction due to evaporation of the second reducing agent. The first and second reduction reactions are performed at a temperature in a range of 550° C. to 650° C., and a temperature in a range of 1000° C. to 1200° C., respectively.