Granulated Powder Binder for Low-Temperature Sintering
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Solution Overview
Problem
Existing powder metallurgy techniques face challenges in achieving high-density sintered bodies at lower firing temperatures due to the use of fine metal powders with low fluidity, which requires expensive high-temperature furnaces and results in poor mechanical properties if the firing temperature is reduced.
Innovation Solution
A granulated powder is produced using metal particles bound with an organic binder containing polyvinyl alcohol, wax, and a nonionic surfactant, which enhances fluidity and densification, allowing for high-density sintering at lower temperatures without the need for specialized furnaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fine metal powder (10 μm or less) is used, then the sintered body can be produced, but the fluidity is poor and the molding die cannot be completely filled
Solution Approach 1:
The invention segments the fine metal powder into granulated particles with controlled size distribution (D10: 5-20 μm, D50: 20-50 μm, D90: 50-100 μm). This segmentation creates larger particles that improve fluidity while maintaining the fine particle characteristics needed for dense sintering, thus resolving the contradiction between filling capability and fluidity.
Solution Approach 2:
The invention uses a composite organic binder system consisting of polyvinyl alcohol, wax, and nonionic surfactant. This composite binder provides both binding strength and fluidity enhancement, allowing the granulated powder to flow smoothly during molding while maintaining structural integrity, thus solving the fluidity problem without sacrificing density.
2Manufacturing precision
If high firing temperature (1200°C or higher) is used, then the density of sintered body is improved, but the furnace becomes expensive and running cost increases
Solution Approach 1:
The invention performs preliminary granulation of the metal powder before molding, creating pre-formed granulated particles with improved fluidity and packing characteristics. This preliminary action allows the powder to be compacted more efficiently at lower temperatures, reducing the firing temperature requirement from 1200°C to below 1000°C, thus avoiding the need for expensive high-temperature furnaces.
Solution Approach 2:
The invention changes the particle size distribution parameters and binder composition to optimize the sintering behavior. By controlling the granulated powder characteristics (D10, D50, D90 values) and using a specific binder formula, the sintering process achieves high density at lower temperatures, eliminating the need for specialized high-temperature furnace equipment.
3Ease of manufacture
If firing temperature is decreased, then the furnace cost is reduced, but the density of sintered body deteriorates and mechanical property becomes poor
Solution Approach 1:
The invention introduces an organic binder as an intermediary substance that facilitates the sintering process at lower temperatures. The binder (polyvinyl alcohol, wax, and nonionic surfactant) acts as a mediator that enhances particle bonding and densification during sintering, allowing high-density sintered bodies to be produced at reduced temperatures without sacrificing mechanical properties.
Solution Approach 2:
The invention employs a composite organic binder system that combines polyvinyl alcohol for binding, wax for fluidity and lubrication, and nonionic surfactant for surface tension control. This composite binder system enables effective sintering at lower temperatures by providing multiple functions simultaneously, thus achieving high density and good mechanical properties without requiring expensive high-temperature furnaces.
4Ease of operation
If granulated powder is used, then the fluidity is improved and molding die can be completely filled, but the particle size becomes larger
Solution Approach 1:
The invention applies local quality control by creating a controlled particle size distribution within the granulated powder. The D10 (5-20 μm) provides fine particles for density, the D50 (20-50 μm) provides optimal fluidity, and the D90 (50-100 μm) ensures complete filling. This local quality differentiation allows the powder to exhibit both good fluidity and high packing density simultaneously.
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 enables the production of sintered bodies with high density and mechanical properties using a cost-effective, standard firing furnace, while maintaining dimensional accuracy and reducing shrinkage ratios.
Implementation Method 1
a plurality of particles in the metal powder are bound to one another by the organic binder, thereby forming a granulated powder
Implementation Method 2
the organic binder contains (i) polyvinyl alcohol or a derivative thereof, (ii) a wax, and (iii) a nonionic surfactant
Data Source
Figure 1A~1B
Figure 2~3
AI summary
A granulated powder comprises a plurality of metal particles and an organic binder. It is obtainable by binding a plurality of metal particles to one another by the organic binder. The organic binder contains (i) polyvinyl alcohol or a derivative thereof, (ii) a wax, and (iii) a nonionic surfactant. The total amount of (i) the wax and (ii) the nonionic surfactant is preferably from 0.01 to 1 part by weight based on 100 parts by weight of the metal particles. Further, the organic binder preferably further contains a polyol and/or an organic amine.