VO2 Sintering Powder for Binder-Free Latent Heat Storage
Solution Overview
Problem
Existing methods for producing vanadium dioxide (VO2) in powder form face challenges such as breakage due to poor mechanical strength and reduced heat storage capacity when sintered, and methods involving binders or resins compromise the effective amount of VO2 per volume, diminishing its heat storage function.
Innovation Solution
A powder material for sintering in a vacuum atmosphere is used, comprising vanadium and oxygen with a specific molar ratio, including VO2 and other vanadium oxides, allowing for the formation of a solid latent heat storage sintered member with improved mechanical strength and heat storage capacity through controlled oxidation and sintering processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If VO2 is sintered by ordinary means to form a solid heat storage material, then the material can maintain its shape and avoid leakage, but the sintered body is not resistant to stress application and easily breaks
Solution Approach 1:
The patent changes the sintering parameters by conducting sintering in a vacuum atmosphere rather than ordinary atmosphere, and by controlling the oxygen partial pressure during sintering. This results in a sintered body with improved mechanical strength that can withstand stress application without easy breakage, while maintaining shape stability for heat storage application
Solution Approach 2:
The patent produces a composite sintered body containing VO2 particles embedded in a matrix structure formed during vacuum sintering. This composite structure, where VO2 particles are bonded together through controlled oxidation and sintering, provides both shape maintenance and enhanced mechanical strength, resolving the contradiction between form stability and structural integrity
2Shape
If binders or resins are used to maintain the form of solid heat storage material, then the material can be molded and utilized, but the effective amount of VO2 per volume is reduced, diminishing heat storage function
Solution Approach 1:
The patent extracts and eliminates the binder or resin component from the heat storage material formulation. By conducting sintering in a vacuum atmosphere, the process directly bonds VO2 particles together without requiring external binding agents, thereby maximizing the effective VO2 content per volume while still achieving moldability and form stability
Solution Approach 2:
The VO2 particles themselves serve as the binding medium through controlled oxidation and sintering in vacuum atmosphere. The material self-bonds without external binders, where the VO2 particles form direct interparticle bonds, eliminating the need for separate binder components and maximizing the functional material content
3Strength
If nanometer-sized VO2 powder particles are sintered to improve density and mechanical strength, then breakage is avoided, but the sample is separated into micrometer-sized aggregated grains with unconfirmed bonding
Solution Approach 1:
The patent changes the sintering parameters by conducting the process in a vacuum atmosphere with controlled oxygen partial pressure. This allows nanometer-sized VO2 particles to sinter into a dense structure with confirmed interparticle bonding, avoiding aggregation into micrometer-sized grains while maintaining mechanical strength and compositional stability
Solution Approach 2:
The patent uses a vacuum atmosphere during sintering, which serves as an inert environment that prevents unwanted oxidation and controls the sintering process. This inert environment enables proper bonding between nanometer-sized particles without aggregation, confirming the bonding structure and maintaining compositional stability throughout the sintered body
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 achieves a high latent heat storage capacity and mechanical strength in the sintered member, with a latent heat value comparable to VO2 and a relative density of 90% or more, suitable for phase change solid heat storage applications.
Implementation Method 1
Use of a powder material for sintering in a vacuum atmosphere
Implementation Method 2
a phase transition occurs from the insulator phase to the metal phase around the critical temperature Tp = 67°C
Implementation Method 3
The latent heat of this phase transition is about 220 J/cc, and an amount of heat equivalent to the latent heat is absorbed from the outside in the temperature rising process
Implementation Method 4
sintering in a vacuum atmosphere
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
[PROBLEM TO BE SOLVED] To provide a solid heat storage material that is made of a VO2-basedinorganic material, is easy to sinter, has a high latent heat storage capacity, and can be suitably used as a phase change solid heat storage material, and a method of manufacturing the same. [SOLUTION] A powder material for sintering of a first aspect of the present invention includes vanadium and oxygen and includes a vanadium oxide represented by the chemical formula VO2 and at least one other type of vanadium oxide, in which, when the molar ratio of V and O in all the powder is expressed as 1 : (2 + d), d is in the range of 0 < d < 0.5.