1. Field of the invention
The present invention relates to a hydrogen-storage alloy system that contains no rare-earth elements, and, more particularly, to a hydrogen-storage alloy system with a stable alloy structure and a high capacity of absorbing and releasing hydrogen under ambient temperature and pressure.
2. Description of Related Art
Owing to energy crisis and harms done to the earth by the present ways of using energy sources, the development of green energy sources, including the usage of natural hydrogen energy, solar energy, bio-energy, geothermal energy, and tidal energy, in the most economic condition becomes a notable research and development subject, and any energy source and method causing no threats to the environmental pollution is studied extensively.
Hydrogen is a chemical element whose reserve ranks the third among all elements in the world. Heat can be produced in a quantity of 140 kJ per kg of hydrogen when hydrogen gas is combusted. In addition to the advantage of an excellent combustion rate, the product produced by the combustion is pollution-free water, and thus hydrogen has become a popular green energy source. Since Ni—H battery features a large storage capacity and a high stability, the Ni—H battery becomes very popular when it comes to the decision of choosing an energy source for applications in different areas, particularly in the research and development of hydrogen fuel cell cars. However, hydrogen is highly flammable, so that if hydrogen is used as energy for generating electric power, the storage of hydrogen becomes a safety issue. On the other hand, hydride features a low price, a high safety, an advantage of not producing green house gases, a high storage capacity, and a property of absorbing and releasing hydrogen easily, and thus hydride is considered as an excellent hydrogen storage material.
In recent years, high-entropy alloy (HEA) is one of the most noticeable materials and composed of at least five principal elements, and each element has an atomic percentage falling within a range of 5%˜35%. After the elements are mixed uniformly in a liquid phase at a high temperature and then cooled, a hydrogen storage alloy with the characteristics of high entropy and low Gibbs free energy is formed. Compared with a conventional alloy, the high-entropy alloy has a simpler microstructure that can be used to produce a nano-scaled material easily and features the advantages of high thermal stability, excellent ductility and compressibility, high hardness, and outstanding electric and magnetic properties. It is noteworthy to point out that the proportion of metal elements selected and mixed to form such an alloy material has a substantial effect of storing hydrogen, and absorbing/desorbing hydrogen of the alloy, and optimal conditions are applied for the usage of the alloy.
Therefore, it is a primary objective of the present invention to provide a hydrogen-storage alloy with an optimal hydrogen-storage performance to enhance the usage. The inventor of the present invention developed a hydrogen-storage alloy that uses a vacuum arc remelting (VAR) method and a thermal treatment, if necessary, to prepare an as-cast high-entropy alloy.
The hydrogen-storage alloys of the present invention have a molecular formula CouFevMnwTixVyZrz, where 0.5≦u≦2.0, 0.5≦v≦2.5, 0.5≦w≦2.0, 0.5≦x≦2.5, 0.4≦y≦3.0 and 0.4≦z≦3.0, and such hydrogen-storage alloys can be a non-equal molar alloy material with a structure of a single C14 Laves phase, and the structure is stable and capable of absorbing and desorbing hydrogen in an operation environment under ambient temperature and pressure and a high ratio of the weight percentage of the total number of hydrogen atoms to the weight percentage of the total number of alloy atoms (H/M value), which indicates a high hydrogen-storage capacity.
The hydrogen-storage alloys of the present invention can be used extensively in the areas of hydrogen storage, heat storage, heat pump, hydrogen purification, isotope separation, secondary battery and fuel cell.
The invention, as well as its many advantages, may be further understood by the following detailed description and drawings in which:
Description of Designations Used for Representing Respective Elements of the Present Invention: According to the design of experiment of the present invention, any alloy with a mole ratio of 1.0 is identical to each other. In other words, A2=B3=C3=D4=E4=F2. An alloy with an equal mole ratio correlates to an indicated alloy of the non-equal molar alloys having different metal contents in the system.
A1 is a high-entropy hydrogen-storage alloy containing titanium of 0.5 mole ratio.
A2 is a high-entropy hydrogen-storage alloy containing titanium of 1.0 mole ratio.
A3 is a high-entropy hydrogen-storage alloy containing titanium of 1.5 mole ratio.
A4 is a high-entropy hydrogen-storage alloy containing titanium of 2.0 mole ratio.
A5 is a high-entropy hydrogen-storage alloy containing titanium of 2.5 mole ratio.
B1 is a high-entropy hydrogen-storage alloy containing zircon of 0.4 mole ratio.
B2 is a high-entropy hydrogen-storage alloy containing zircon of 0.7 mole ratio.
B3 is a high-entropy hydrogen-storage alloy containing zircon of 1.0 mole ratio.
B4 is a high-entropy hydrogen-storage alloy containing zircon of 1.3 mole ratio.
B5 is a high-entropy hydrogen-storage alloy containing zircon of 1.7 mole ratio.
B6 is a high-entropy hydrogen-storage alloy containing zircon of 2.0 mole ratio.
B7 is a high-entropy hydrogen-storage alloy containing zircon of 2.3 mole ratio.
B8 is a high-entropy hydrogen-storage alloy containing zircon of 2.6 mole ratio.
B9 is a high-entropy hydrogen-storage alloy containing zircon of 3.0 mole ratio.
C1 is a high-entropy hydrogen-storage alloy containing vanadium of 0.4 mole ratio.
C2 is a high-entropy hydrogen-storage alloy containing vanadium of 0.7 mole ratio.
C3 is a high-entropy hydrogen-storage alloy containing vanadium of 1.0 mole ratio.
C4 is a high-entropy hydrogen-storage alloy containing vanadium of 1.3 mole ratio.
C5 is a high-entropy hydrogen-storage alloy containing vanadium of 1.7 mole ratio.
C6 is a high-entropy hydrogen-storage alloy containing vanadium of 2.0 mole ratio.
C7 is a high-entropy hydrogen-storage alloy containing vanadium of 2.3 mole ratio.
C8 is a high-entropy hydrogen-storage alloy containing vanadium of 2.6 mole ratio.
C9 is a high-entropy hydrogen-storage alloy containing vanadium of 3.0 mole ratio.
D1 is a high-entropy hydrogen-storage alloy containing manganese of 0 mole ratio.
D2 is a high-entropy hydrogen-storage alloy with manganese of 0.5 mole ratio.
D3 is a high-entropy hydrogen-storage alloy with manganese of 0.75 mole ratio.
D4 is a high-entropy hydrogen-storage alloy with manganese of 1.0 mole ratio.
D5 is a high-entropy hydrogen-storage alloy with manganese of 1.25 mole ratio.
D6 is a high-entropy hydrogen-storage alloy with manganese of 1.5 mole ratio.
D7 is a high-entropy hydrogen-storage alloy with manganese of 2.0 mole ratio.
E1 is a high-entropy hydrogen-storage alloy containing cobalt with a mole ratio equal to 0.
E2 is a high-entropy hydrogen-storage alloy containing cobalt with a mole ratio equal to 0.5.
E3 is a high-entropy hydrogen-storage alloy containing cobalt with a mole ratio equal to 0.75.
E4 is a high-entropy hydrogen-storage alloy containing cobalt with a mole ratio equal to 1.0.
E5 is a high-entropy hydrogen-storage alloy containing cobalt with a mole ratio equal to 1.25.
E6 is a high-entropy hydrogen-storage alloy containing cobalt with a mole ratio equal to 1.5.
E7 is a high-entropy hydrogen-storage alloy containing cobalt with a mole ratio equal to 2.0.
F1 is a high-entropy hydrogen-storage alloy containing iron with a mole ratio equal to 0.5.
F2 is a high-entropy hydrogen-storage alloy containing iron with a mole ratio equal to 1.0.
F3 is a high-entropy hydrogen-storage alloy containing iron with a mole ratio equal to 1.25.
F4 is a high-entropy hydrogen-storage alloy containing iron with a mole ratio equal to 1.5.
F5 is a high-entropy hydrogen-storage alloy containing iron with a mole ratio equal to 2.0.
F6 is a high-entropy hydrogen-storage alloy containing iron with a mole ratio equal to 2.5.
The technical characteristics and preparation method of the hydrogen-storage alloy of the present invention will become apparent with the detailed description of preferred embodiments and the illustration of related drawings as follows.
The hydrogen-storage alloy of the present invention has a molecular formula of CouFevMnwTixVyZrz, wherein 0.5≦u≦2.0, 0.5≦v≦2.5, 0.5≦w≦2.0, 0.5≦x≦2.5, 0.4≦y≦3.0 and 0.4≦z≦3.0.
The first embodiment is provided to illustrate a common method of preparing the hydrogen storage alloy of the present invention, and an equivalent preparation method such as a mechanical-alloying method can be used.
The hydrogen storage alloy of the present invention is cast by melting pure metal lumps by a vacuum arc remelter (VAR) to produce the alloy, wherein each pure metal is placed on a water-cooled copper crucible, and then a vacuum pump is turned on until the pressure reaches 2×10−2 torr, and a valve of the pump is shut, and argon gas is pumped in repeatedly to maintain the pressure at 200 ton, so as to assure a sufficiently low pressure of oxygen in the furnace, such that only the argon gas with a pressure lower than 1 atmosphere can be passed through and ignited by an electric arc, and the metal is melted to a molten form, and after the electric arc stirs the molten metal uniformly, the power is turned off, and the alloy is turned upside down. The aforementioned melting process is repeated for several times, and the alloy is cooled completely and is taken out.
The second embodiment is provided to show the effect of different titanium (Ti) contents.
With reference to
Referred to
The third embodiment is provided to show the effect of different zirconium (Zr) contents.
With reference to
The fourth embodiment is provided to show the effect of different vanadium (V) contents.
With reference to
The fifth embodiment is provided to show the effect of different manganese (Mn) contents.
With reference to
The sixth embodiment is provided to show the effect of different cobalt (Co) contents.
Referred to
The seventh embodiment 7 is provided to show the effect of different iron (Fe) contents.
With reference to
In
In summation of the description above, the content of each metal in the hydrogen-storage alloy of the present invention is adjusted to achieve the hydrogen-storage alloy, such that the hydrogen has excellent hydrogen absorption/desorption and hydrogen-storage capacities in an operation environment at ambient temperature and pressure, and the hydrogen-storage alloy has the potential to become a green energy source.
Many changes and modifications in the above-described embodiment of the invention can, of course, be carried out without departing from the scope thereof Accordingly, to promote the progress in science and the useful arts, the invention is disclosed and is intended to limit only by the scope of the appended claims.
Number | Date | Country | Kind |
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099131383 | Sep 2010 | TW | national |