TiNi Alloy Composition for Controlling Thermal Storage Phase Change
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing TiNi-based alloys for thermal storage materials face challenges in individually controlling phase transformation heat and temperature, leading to limited application range and difficulty in processing complex shapes due to brittleness and low thermal conductivity.
Innovation Solution
A TiNi-based alloy with controlled martensite start temperature (Ms) and austenitic finish temperature (Af) through specific composition and processing, allowing for strain introduction and adjustment, enabling flexible shape formation and enhanced thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If water or paraffin is used as thermal storage material, then transformation heat per volume is very high (200 J/cc or more), but thermal conductivity is very low (about 1 W/mK) making it difficult to efficiently take heat into the material and dissipate heat to the outside
Solution Approach 1:
The patent uses TiNi-based alloy as a composite thermal storage material that combines high transformation heat (230 J/cc) with high thermal conductivity, overcoming the limitation of conventional materials like water or paraffin which have low thermal conductivity despite high transformation heat
2Quantity of substance
If water or paraffin is used as thermal storage material, then transformation heat is high, but it is difficult to maintain a regular shape of the material because it is necessary to encapsulate the liquid and the shape is limited to a simple shape
Solution Approach 1:
The patent utilizes the solid-solid phase transformation capability of TiNi-based alloy, which can reversibly change between martensitic and austenitic phases, enabling the material to maintain regular shapes while providing high transformation heat without requiring encapsulation
3Quantity of substance
If oxide ceramics such as Ti2O3 and VO2 are used for thermal storage, then transformation heat is comparable to solid-liquid (200 to 250 J/cc), but the material is poor in ductility and processability and is difficult to process into a complicated shape
Solution Approach 1:
The patent employs TiNi-based alloy which combines the high transformation heat characteristic of oxide ceramics (230 J/cc) with superior ductility and processability, allowing the material to be easily formed into complicated shapes while maintaining high thermal storage capacity
4Ease of manufacture
If TiNi-based alloy is used for thermal storage, then thermal conductivity is higher than ceramics and shape flexibility is improved, but phase transformation heat and phase transformation temperature cannot be individually controlled
Solution Approach 1:
The patent independently controls phase transformation heat and phase transformation temperature by adjusting alloy composition parameters (Ti, Ni, Cu, Co, Cr, Zr, Fe content) and heat treatment parameters (heating temperature, holding time, cooling rate), enabling the material to be tailored for specific application requirements
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 alloy achieves individual control of phase transformation heat and temperature, facilitating wider application and efficient heat storage/dissipation across a broader temperature range, with improved processability and flexibility.
Implementation Method 1
a TiNi-based alloy exhibiting martensitic transformation as a solid-solid phase change is used. In the TiNi-based alloy, the transformation finish temperature (Af temperature) to the high temperature phase (austenitic phase) during heating is the endothermic completion temperature, and the transformation start temperature (Ms temperature) to the low temperature phase (martensitic phase) during cooling is the heat dissipation start temperature
Implementation Method 2
the alloy is capable of dissipating heat upon application of external stress after being endothermically heated to a temperature of Af temperature or higher
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A TiNi-based alloy having a martensite start temperature (Ms temperature) and satisfying the following formula (1): Ms−Ms900°C≥2°C wherein Ms is an Ms temperature (°C) of the alloy measured according to JIS H7101:2002, and Ms900°C is an Ms temperature (°C) of the alloy measured according to JIS H7101:2002 after the alloy is heated at 900°C for 1 hour.