Iron Powder Bulk Density Control for Exothermic Composition
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Solution Overview
Problem
Conventional exothermic warmers using iron powder struggle to maintain high exothermic performance and handleability, as the bulk density of the iron powder affects the oxidation reaction efficiency and the ability to reduce the size of the exothermic body.
Innovation Solution
An iron powder with a bulk density of 0.3 to 1.5 g/cm³, average particle size of 20 to 150 µm, and a pore volume of 0.3 cm³/g or more is produced, combined with a carbon material and halide salt, to enhance exothermic properties and handleability in an exothermic composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the bulk density of iron powder is increased to improve exothermic performance, then the oxidation reaction efficiency is improved, but the exothermic body thickness cannot be reduced
Solution Approach 1:
The patent applies parameter changes by precisely controlling the bulk density of iron powder within the range of 0.3 to 1.5 g/cm³, along with controlling particle size (20-150 µm) and pore volume (0.3 cm³/g or more). These parameter optimizations enable the iron powder to achieve high oxidation reaction efficiency while maintaining low density, thus resolving the contradiction between improving exothermic performance and reducing exothermic body thickness.
2Volume of moving object
If the bulk density of iron powder is decreased to reduce exothermic body thickness, then the exothermic body size is reduced, but the oxidation reaction efficiency deteriorates
Solution Approach 1:
The patent resolves this contradiction by establishing an optimal parameter range for bulk density (0.3 to 1.5 g/cm³) that is lower than conventional iron powder but still maintains high oxidation reaction efficiency. This is achieved through coordinated control of multiple parameters including particle size and pore volume, allowing the exothermic body thickness to be reduced while preserving exothermic performance.
Solution Approach 2:
The patent creates a composite structure within the iron powder by controlling pore volume to be 0.3 cm³/g or more, effectively creating a porous composite material that combines low density with high reactivity. This composite approach allows the iron powder to achieve both reduced exothermic body thickness and maintained oxidation reaction efficiency.
3Power
If highly active iron powder is used to improve exothermic properties, then the temperature increase rate and exothermic performance are improved, but the handleability and preservation stability deteriorate
Solution Approach 1:
The patent applies parameter changes by controlling the bulk density within the specific range of 0.3 to 1.5 g/cm³ and particle size within 20-150 µm. These parameter optimizations achieve a balance where the iron powder maintains high exothermic performance through appropriate surface area and reactivity, while the controlled bulk density and particle size ensure good handleability and preservation stability, preventing excessive reactivity that would compromise operational ease.
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 iron powder with specific properties improves the oxidation reaction efficiency, allowing for longer heat generation and reduced exothermic body thickness, while maintaining preservation stability and coating properties.
Implementation Method 1
an exothermic body generates heat using reaction heat obtained through an oxidation reaction of an iron powder contained in the exothermic body
Implementation Method 2
generates heat using reaction heat obtained through an oxidation reaction
Data Source
Figure 1(a)~1(c)
Figure 2(a)~2(b)
Figure 3
AI summary
An iron powder for an exothermic composition according to the present invention has a bulk density of 0.3 to 1.5 g/cm3. Furthermore, an exothermic composition according to the present invention contains the iron powder, a carbon material, a halide salt, and water. Furthermore, an exothermic body production method according to the present invention includes: forming a coated member by coating a base material sheet with a flowable exothermic composition containing the iron powder, a carbon material, and water; and adjusting an amount of moisture in the coated member by removing water from the coated member. Furthermore, the present invention is directed to a production method for the iron powder (an iron powder for an exothermic composition) including: a reducing step of reducing iron oxide to obtain reduced iron; and a step of milling the reduced iron. In the reducing step, the iron oxide is reduced by introducing iron oxide and a solid reductant with a volatile matter content of 10% by mass or more into a heating furnace whose internal portion contains no sulfur gas or is set to an air or inert gas atmosphere, and setting the internal portion to a reducing gas atmosphere through heating under a condition that an ambient temperature of the internal portion is from 900 to 1000°C.