Heat-dissipating ceramic foam containing carbonized cellulose particles and method for producing the same

Abstract

The present disclosure provides a method for producing a heat-dissipating ceramic foam containing carbonized cellulose particles, the method including: mixing particles of carbonized cellulose or carbonized cellulose-containing substance, ceramic powders, silicate, and water to form slurry; adding a foaming agent to the slurry to form foamed slurry; and drying the foamed slurry.

Claims

1. A method for producing a heat-dissipating ceramic foam containing coffee grounds comprising cellulose carbides and having uniform size and distribution of pores, the method comprising: mixing coffee grounds comprising cellulose carbides, ceramic powders, silicate, and water to form slurry; adding hydrogen peroxide to the slurry to form foamed slurry; and drying the foamed slurry.

2. The method of claim 1, wherein the ceramic powder includes at least one selected from a group consisting of elvan, ocher stone, olivine, kaolin, silica mineral, diatomite, wollastonite, pyrophyllite, dolomite, lithium minerals, magnesite, bauxite, bentonite, pumice, borate, serpentine, acid clay, iron oxide, garnet, carbonate minerals, attapulgite, sepiolite, nephrite, apatite, illite-mica, feldspar, perlite, vermiculite, zeolite, barite, talc, diatomaceous earth, graphite, hectorite, clay minerals, zirconium minerals, titanium minerals, tourmaine, fume silica, aerogel, fly ash, and blast furnace slag.

3. The method of claim 1, wherein the silicate includes at least one selected from a group consisting of sodium silicate, powdered sodium silicate, potassium silicate, lithium silicate, and sodium alumino-silicate.

4. The method of claim 1, wherein mixing includes mixing the coffee grounds comprising cellulose carbides, ceramic powder, silicate, water, and metal powders, wherein the metal powders include at least one selected from a group consisting of Au, Ag, Zn, Al, Fe, Mg and Sn.

5. The method of claim 1, wherein mixing includes mixing the coffee grounds comprising cellulose carbides, ceramic powder, silicate, water, and activated carbons.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 to FIG. 4 are photographs illustrating foaming agents prepared in Example 1 to Example 4, respectively.

(2) FIG. 5A to FIG. 8B are photographs of the foams as taken by a thermal imaging camera, wherein the foams prepared in Example 1 to Example 4 are attached to LED chips respectively.

DETAILED DESCRIPTIONS

(3) Examples of various embodiments are illustrated and described further below. It is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the present disclosure as defined by the appended claims. Examples of various embodiments are illustrated and described further below. It will be understood that the description herein is not intended to limit the claims to the specific embodiments described. The same reference numbers in different figures denote the same or similar elements, and as such work similar functionality.

(4) The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms a and an are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms comprises, comprising, includes, and including when used in this specification, specify the presence of the stated features, integers, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, operations, elements, components, and/or portions thereof. As used herein, the term and/or includes any and all combinations of one or more of the associated listed items. Expression such as at least one of when preceding a list of elements may modify the entire list of elements and may not modify the individual elements of the list.

(5) Unless otherwise defined, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this inventive concept belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

(6) 1. Preparation and Physical Properties Evaluation of Foam

Example 1

(7) 5 g of silica, 2 g of aluminum powder, 12.5 g of PVA, 20 ml of liquid silicate, and 15 ml of water were mixed to form slurry. 1 ml of hydrogen peroxide was added to the slurry to foam the slurry. The foamed slurry was heated at 100 C. for 10 hours and dried to obtain a foam as shown in FIG. 1.

(8) The foam obtained in Example 1 was easily broken and has small pores and large pores coexisted therein. Thus, the pores were not uniform or dense. A large pore region in which particle-to-particle bonds were not formed was observed.

Example 2

(9) A foam was prepared in the same manner as in Example 1 except that 12.5 g of graphite was added for slurry preparation. The thus-prepared foam is shown in FIG. 2.

(10) In the foam obtained in Example 2, only large pores were present. The foam was easily broken when it was pressed down strongly. From this, it was found that the foam having sufficient strength and sufficient porosity could not be prepared only when the carbon particles were added to increase the thermal conductivity.

Example 3

(11) A foam was prepared in the same manner as in Example 2 except that 12.5 g of activated carbons were added instead of graphite. The thus-prepared foam is shown in FIG. 3.

(12) It was confirmed that the foam obtained in Example 3 had insufficient pores as a whole. The foam had a strong strength so that it did not break even when it was thrown down.

Example 4

(13) A foam was prepared in the same manner as in Example 2 except that 12.5 g of coffee grounds were added instead of graphite. The thus-prepared foam is shown in FIG. 4.

(14) The foam obtained in Example 4 had a small pore size and a uniform pores distribution. The pore size was about 2 mm. The foam had enough strength not to be broken even when it was dropped down from 80 cm height above.

(15) 2. Evaluation of Heat Sink Characteristics of Prepared Foam

(16) The heat sink characteristics of the foams as prepared in the above Examples were evaluated. After the foams prepared in the above Examples were attached to the LED chips respectively, the temperature of the foams and the LED chips 15 minutes after supply of power to the LED chips were measured with a thermal imaging camera.

(17) FIG. 5A to FIG. 8B correspond to the foams of Example 1 to Example 4, respectively.

(18) FIG. 5B shows the temperature of the LED chip which is attached to the foam prepared in Example 1 as measured by the thermal imaging camera. The measured temperature was 86.6 C. FIG. 6B shows the temperature of the LED chip which is attached to the foam prepared in Example 2 as measured by the thermal imaging camera. The measured temperature was 80.0 C. FIG. 7B shows the temperature of the LED chip which is attached to the foam prepared in Example 3 as measured by the thermal imaging camera. The measured temperature was 78.4 C. FIG. 8B shows the temperature of the LED chip which is attached to the foam prepared in Example 4 as measured by the thermal imaging camera. The measured temperature was 75.2 C. From those, it was confirmed that the foam prepared in Example 4 containing coffee grounds exhibits the optimal performance as the heat sink.

(19) In particular, the optimal performance is proven by the measurements of the temperatures of the foams. FIG. 5A illustrates a temperature measurement of the foam of Example 1 with the thermal imaging camera. The temperature measurement thereof is 29.5 C. FIG. 6A illustrates a temperature measurement of the foam of Example 2 with the thermal imaging camera. The temperature measurement thereof is 36.8 C. FIG. 7A illustrates a temperature measurement of the foam of Example 3 with the thermal imaging camera. The temperature measurement thereof is 43.4 C. FIG. 8A illustrates a temperature measurement of the foam of Example 4 with the thermal imaging camera. The temperature measurement thereof is 52.7 C. From those, it was confirmed that the foam prepared in Example 4 containing coffee grounds exhibits a highest heat dissipation rate from the LED chip.