Nano-structured Aluminum Nitride (AlN) in a pure form and in the wurtzite phase of AlN from nut shells

Abstract

Nano-structures of Aluminum Nitride and a method of producing nano-structures of Aluminum Nitride from nut shells comprising milling agricultural nuts into a fine nut powder, milling nanocrystalline Al.sub.2O.sub.3 into a powder, mixing, pressing the fine nut powder and the powder of nanocrystalline Al.sub.2O.sub.3, heating the pellet, maintaining the temperature of the pellet at about 1400° C., cooling the pellet, eliminating the residual carbon, and forming nano-structures of AlN. An Aluminum Nitride (AlN) product made from the steps of preparing powders of agricultural nuts using ball milling, preparing powders of nanocrystalline Al.sub.2O.sub.3, mixing the powders of agricultural nuts and the powders of nanocrystalline Al.sub.2O.sub.3 forming a homogenous sample powder of agricultural nuts and Al.sub.2O.sub.3, pressurizing, pyrolizing the disk, and reacting the disk and the nitrogen atmosphere and forming AlN.

Claims

1. A nano-structured Aluminum Nitride (AlN) in a pure form and in the wurtzite phase of AlN from nut shells made from the steps of: preparing powders of agricultural nuts using ball milling including stainless steel milling media; preparing powders of nanocrystalline Al.sub.2O.sub.3 using ball milling including stainless steel milling media; mixing the powders of agricultural nuts and the powders of nanocrystalline Al.sub.2O.sub.3 using ball milling including stainless steel milling media and thereby forming a homogenous sample powder of agricultural nuts and Al.sub.2O.sub.3; pressurizing the homogenous sample powder of agricultural nuts and Al.sub.2O.sub.3 into a disk; heat treating or pyrolizing the disk in a nitrogen atmosphere; and reacting the disk and the nitrogen atmosphere and forming AlN; wherein the AlN is nano-structured AlN and in a pure form and in the wurtzite phase of AlN.

2. The nano-structured Aluminum Nitride (AlN) in a pure form and in the wurtzite phase of AlN from nut shells of claim 1 further comprising the step of: eliminating residual carbon by placing the disk in air after the step of reacting the disk and the nitrogen atmosphere and forming AlN.

3. The nano-structured Aluminum Nitride (AlN) in a pure form and in the wurtzite phase of AlN from nut shells of claim 2 wherein the step of heat treating or pyrolizing the disk comprises temperatures exceeding 1400° C. for an interval of 5-6 hours in a nitrogen atmosphere.

4. The nano-structured Aluminum Nitride (AlN) in a pure form and in the wurtzite phase of AlN from nut shells of claim 1 wherein the step of eliminating the residual carbon by placing the disk in air involves a temperature of 670° C.; and wherein the step of heat treating or pyrolizing the disk comprises a conventional furnace.

5. A nano-structured Aluminum Nitride product from nut shells in a pure form and in the wurtzite phase from the steps comprising: milling agricultural nuts into a fine nut powder; milling nanocrystalline Al.sub.2O.sub.3 into a powder; mixing the fine nut powder with the powder of nanocrystalline Al.sub.2O.sub.3; pressing the fine nut powder and the powder of nanocrystalline Al.sub.2O.sub.3 into a pellet; providing a nitrogen atmosphere; heating the pellet to a temperature of about 1400° C.; maintaining the temperature of the pellet at about 1400° C.; cooling the pellet in air to a temperature of about 670° C.; eliminating the residual carbon; and forming nano-structures of AlN.

6. A nano-structured Aluminum Nitride product from nut shells in a pure form and in the wurtzite phase from the steps comprising: milling agricultural nuts into a fine nut powder; milling nanocrystalline Al.sub.2O.sub.3 into a powder; mixing the fine nut powder with the powder of nanocrystalline Al.sub.2O.sub.3; wherein the fine nut powder of agricultural nuts is prepared using ball milling with a SPEX 8000M including stainless steel milling media; wherein the powder of nanocrystalline Al.sub.2O.sub.3 is prepared using ball milling including stainless steel milling media; wherein the fine nut powder of agricultural nuts and the powder of nanocrystalline Al.sub.2O.sub.3 are mixed using ball milling including stainless steel milling media and thereby forming a homogenous sample powder of agricultural nuts and Al.sub.2O.sub.3; pressing the fine nut powder and the powder of nanocrystalline Al.sub.2O.sub.3 into a pellet; providing a nitrogen atmosphere; heating the pellet to a temperature of about 1400° C.; wherein the step of heating the pellet comprises a conventional furnace; and wherein the step of pressing utilizes a hydraulic press; maintaining the temperature of the pellet at about 1400° C.; cooling the pellet in air to a temperature of about 670° C.; eliminating the residual carbon; and forming nano-structures of AlN; wherein the AlN is nano-structured AlN and in a pure form and in the wurtzite phase of wherein an 18 kW rotating anode generator and a high resolution powder diffractometer characterize the structure of the nano-structured AlN in a pure form and in the wurtzite phase with monochromatic CuKα radiation and further using a 514 nm laser line to obtain Raman spectra on an inVia Raman Microscope and scanning at about 15 mW laser power and an integration period of 30 seconds.

Description

DESCRIPTION OF THE DRAWINGS

[0017] The following description and drawings set forth certain illustrative implementations of the disclosure in detail, which are indicative of several exemplary ways in which the various principles of the disclosure may be carried out. The illustrated examples, however, are not exhaustive of the many possible embodiments of the disclosure. Other objects, advantages and novel features of the disclosure will be set forth in the following detailed description when considered in conjunction with the drawings.

[0018] FIG. 1 illustrates X-ray diffraction patterns taken with CuKα radiation of AlN synthesized from Almond powder and aluminum oxide powder in nitrogen at a temperature of 1450° C. showing the wurtzite phase.

[0019] FIG. 2A illustrates a TEM micrograph of AlN samples fabricated from almond showing the nanocrystalline nature.

[0020] FIG. 2B illustrates a TEM micrograph of AlN samples fabricated from almond showing the nanocrystalline nature.

[0021] FIG. 2C illustrates a TEM micrograph of AlN samples fabricated from walnut showing the nanocrystalline nature.

[0022] FIG. 2D illustrates a TEM micrograph of AlN samples fabricated from walnut showing the nanocrystalline nature.

[0023] FIG. 3 illustrates Raman Spectra of the AlN sample derived from almond confirming the wurtzite phase.

[0024] FIG. 4A illustrates X-ray diffraction scan of Al.sub.2O.sub.3 mixed with almond showing peaks corresponding to corundum phase. The vertical lines correspond to the expected peaks of alumina.

[0025] FIG. 4B illustrates a Rietveld whole profile analysis of the diffraction pattern for the AlN sample derived from almond after pyrolising in a nitrogen atmosphere followed by treatment in air at 800° C.

[0026] FIG. 5A illustrates Raman spectra of AlN derived from pistachio showing the different Raman active modes.

[0027] FIG. 5B illustrates Raman spectra of AlN derived from almond showing the different Raman active modes.

[0028] FIG. 5C illustrates FTIR spectra of AlN derived from pistachio showing a broad band of 699 cm.sup.−1.

[0029] FIG. 5D illustrates FTIR spectra of AlN derived from almond showing a broad band of 698 cm.sup.−1.

[0030] FIG. 6 illustrates EDX of AlN derived from almond nut shell after pyrolysing in N.sub.2 and followed by heat treatment in O.sub.2 to remove excessive carbon.

DETAILED DESCRIPTION OF THE INVENTION

[0031] A method of making Aluminum Nitride Synthesis from Nut Shells.

[0032] Here, the inventors have discovered a method of forming pure AlN by carbothermal reduction of Al.sub.2O.sub.3 with raw nuts of almonds, coconuts, macadamia, pistachios, and walnuts in the presence of a N.sub.2 atmosphere to produce nano-tubes and nanoparticles previously not formed by other processing then purified in an O.sub.2 atmosphere in a Al.sub.2O.sub.3 crucible.

Example 1

[0033] The production process involves preparing samples from powders of raw nuts of almonds, coconuts, macadamia, pistachios, and walnuts after mixing them with nanocrystalline Al.sub.2O.sub.3 powder using ball milling with a SPEX 8000M including stainless steel milling media.

Example 2

[0034] The Al.sub.2O.sub.3 sample along with the specific nut shell was combined and milled to obtain a uniform powder. A hydraulic press was used to pressurize the homogenous powder into 1 cm diameter disks with a 2.5-3 mm depth.

[0035] The pellets were heat treated (pyrolised) in a conventional furnace at temperatures exceeding 1400° C. for an interval of 5-6 hours in a nitrogen atmosphere.

[0036] In order to eliminate the residual carbon, the pellets were then placed in air at 670° C.

Example 3

[0037] XRD scans were obtained using a Rigaku 18 kW rotating anode generator and a high resolution powder diffractometer. The diffraction scans were collected using monochromatic CuKα radiation.

[0038] Raman spectra were collected on an inVia Raman Microscope (Renishaw) using a 514 nm laser line.

[0039] Scans were obtained at ca. 15 mW laser power at the sample and an integration period of 30 seconds.

[0040] Fourier Transform Infrared (FTIR) spectra were collected using Thermo Scientific Nicolet FT-IR spectrometer with Diffuse Reflectance Infrared Transform Spectroscopy (DRIFTS) accessory.

Example 4

[0041] In order to conduct the TEM analysis, ethyl alcohol was mixed with the pyrolyzed sample; the mixture was then set in an ultrasonic cleaner.

[0042] A carbon covered 200 mesh copper grid was submerged into the mixture to collect AlN particles.

[0043] A FEI Tecnai G2 TEM was utilized to examine the sample at 300 kV.

[0044] Nuts have very little SiO.sub.2 uptake from the ground but still is a carbon source. Therefore nuts are a great candidate to mix with oxides to form a carbide and/or a nitride with further processing. The result is a pure nitride (in this case AlN) that is made in a simple cost effective process.

[0045] AlN made from nuts such as almonds, pistachios, walnuts, cashew, coconuts, macadamia etc. can be made fully dense without the use of other dopants like AlN made in other ways. This provides a more pure bulk form of AlN.

[0046] Due to its unique properties, it is extremely useful for the Navy. AlN its applications have been developed mainly for military aeronautics and transport fields.

[0047] Other applications of AlN lie in refractory composites for handling of aggressive molten metals, and high efficiency heat exchange systems.

[0048] The formation of pure AlN from nut shells offers a simple route as compared to complicated reactions currently being used involving carbon rich agents and at elevated temperatures.

[0049] Moving to more environmentally greener processes is important. This process should become the standard processing for obtaining Pure AlN.

[0050] The above examples are merely illustrative of several possible embodiments of various aspects of the present disclosure, wherein equivalent alterations and/or modifications will occur to others skilled in the art upon reading and understanding this specification and the annexed drawings. In addition, although a particular feature of the disclosure may have been illustrated and/or described with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application. Also, to the extent that the terms “including”, “includes”, “having”, “has”, “with”, or variants thereof are used in the detailed description and/or in the claims, such terms are intended to be inclusive in a manner similar to the term “comprising”.