The present invention generally relates to method for manufacturing lightweight high-strength material using middle fragments of shell and, more particularly, to method for making tablets from shells to laminate and rearrange them using adhesives.
Lightweight strong materials are necessary in most of the industries such as automobile, aerospace, electronics, telecommunication, military, etc. Lightweight bulletproof materials with excellent mechanical properties are needed especially in the military industry. However, currently available materials such as boron carbide, silicon carbide, etc. are not very available because of their high prices. Natural materials with lightweight bulletproof properties and better mechanical properties are available though so are various artificial materials too.
The shell of shellfish that has evolved over hundreds of millions of years is one of the natural materials and has excellent mechanical properties in terms of weight and thickness. For instance, the shell has the specific gravity of about 2.6, similar to that of boron carbide and less than that of silicon carbide and aluminum nitride.
The shell has excellent mechanical properties owing to its ‘brick and mortar’ structure that looks like the lamination of thousands of about 0.5 μm thin brick-like tablets. When external force is applied to the shell, its crack can be expected to go along among micro-tablets but the applied external force and energy to the shell are actually absorbed due to its peculiar structure so that its crack cannot keep going along further but stop in the middle. However, it is difficult at the moment to reproduce the natural ‘brick and mortar’ structure of the shell because it is not easy for human to laminate thousands of micro-tablets.
Furthermore, recently the amount of the shells dumped on the coast every year reaches 500,000 tons, it causes environmental pollution including serious water pollution. Shells are the natural materials with great usability, and it is necessary to actively utilize them so as to prevent environmental pollution.
The present invention advantageously provides a method for manufacturing lightweight material with excellent mechanical properties out of the shells which are one of the natural waste resource.
In an embodiment of the present invention, a method for manufacturing lightweight high-strength material comprises the steps of: making tablets out of shells, and laminating and rearranging the tablets.
Preferably, the laminated and rearranged structure is hierarchical structure.
Preferably, the tablets are adhered with an adhesive so as to be laminated and rearranged. The adhesive is epoxy or urethane-based adhesive. The adhesive further includes fiber fragments made from glass or carbon. The tablets are laminated and rearranged using the adhesive and the prepregs made from glass fiber or carbon fiber together.
Furthermore, in another embodiment of the present invention, a lightweight high-strength material is manufactured in the method of the above embodiment.
According to the present invention, lightweight high-strength material is manufactured by making tablets out of shells and laminating and rearranging them, so that it can be applied to various industries and environmental problems can be solved at the same time.
Various exemplary embodiments of the invention are fully discussed hereinafter with reference to the accompanying drawings.
In this specification, shell refers to the shell of shellfish and the shellfish is a generic name for mollusks belonging to shellfish class. Typical shellfish includes oysters, clams, Manila clams, blood clams, abalone and so forth. Over hundreds of millions of years, these shells have evolved to have ‘brick and mortar’ structure of micro-tablets and have been found to be 3000 times stronger in fracture toughness. In this embodiment, shells are used due to their features and the shells dumped on the coast can be used so that environmental problems can be solved at the same time.
The micro-tablets of a shell are arranged in ‘brick and mortar’ structure so that the shell has strong mechanical properties. However, since it is extremely difficult to artificially construct it, it can be a good choice to use the method for making meso plates from shells in which micro-tablets are well arranged and then laminated.
The chemical composition of the shell is all calcium carbonate but its outer part has calcite structure with high hardness while its inner part has aragonite structure with relatively low hardness. A calcite is a carbonate anhydrous mineral which has such hexagonal crystal structure that it is easy to produce a plate with beauty owing to its outstanding crystal shape and its various forms. An aragonite is a calcite kind mineral which has orthorhombic crystal structure that an olivine has, but it has higher hardness and higher specific gravity than a calcite has. It is because an aragonite and a calcite have different crystal structures from each other.
So, it is possible to manufacture a material from shells by cutting or peeling calcite parts and aragonite parts from shells to use them depending on the required physical properties or the required uses of the materials, and adjusting and properly mixing their thickness, size, shape, etc.
The structure in which such tablets are rearranged enhances its mechanical strength because it prevents a crack from going further when impact is applied. This structure may mimic hierarchical structure in their form.
A urethane-based adhesive such as epoxy, gelatinous glue, etc. is used to adhere tablets but the adhesive is not limited thereto. Depending on the required final physical properties, the amount and thickness of the adhesive, the pressure of press, the rolling pressure, curing temperature and duration, etc. can be controlled and adjusted. The tablets can be adhered various way. They can be adhered with epoxy only, with pressure, or with heat.
Although the carbon fiber prepregs are inserted between the tablets made in the form of flat plates in this embodiment, the mechanical properties can be controlled by mixing an adhesive such as epoxy with the fiber fragments made from glass or carbon
Since the tablets (1 cm×1 cm×0.1 cm for instance) are cut out of shells. Such a tablet is formed of about 100 millions of micro-tablets (10 μm×10 μm×0.5 μm for instance) laminated in ‘brick and mortar’ structure, it has excellent mechanical properties.
The boards (10 cm×10 cm×1 cm for instance) are made by making tablets of a uniform size and laminating them with an adhesive such as epoxy in ‘brick and mortar’ structure.
After the plates (10 cm×10 cm×0.1 cm for instance) are made by making tablets of a uniform size and laminating them with an adhesive such as epoxy in ‘brick and mortar’ structure to make a board, the fiber enhanced boards (10 cm×10 cm×1 cm) are made by inserting carbon fiber prepregs between the plates and adhering the plates with epoxy.
Although the embodiments of the present invention are described in detail above, they are merely preferred implementation to those skilled in the art. So, the scope of the present invention is not limited thereto. Therefore, the substantial scope of the present invention is defined by the appended claims and the equivalents thereof.
Number | Date | Country | Kind |
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10-2017-0067978 | May 2017 | KR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/KR2018/006227 | 5/31/2018 | WO | 00 |