Vanadium sesquioxide nanocomposite

• US 20100321147A1
• Filed: 06/23/2009
• Published: 12/23/2010
• Est. Priority Date: 06/23/2009
• Status: Abandoned Application

• Current Assignee: King Abdul AZIZ University
• Original Assignee: King Abdul AZIZ University
• Inventors: El-Mossalamy, El-Sayed Ed-Badaway H., Aal, Nadia Abdel, Al-Ghamdi, Ahmed Abdullah S., El-Tantawy, Farid Mahmoud
• Application Number:
  US12/457,851
• Publication Number:
  US 20100321147A1
• Time in Patent Office: Days
• US Class Current: 338/22R
• CPC Class Codes: B29C 2945/7615 Electrical properties
• CPC Class Codes: B29C 2945/76454 Electrical, e.g. thermocouples
• CPC Class Codes: B29C 2945/76635 Electrical properties
• CPC Class Codes: B29C 33/0083 Electrical or fluid connection systems therefor
• CPC Class Codes: B29C 39/006 Monomers or prepolymers by reaction injection moulding B29C67/246
• CPC Class Codes: B29C 45/14639 for obtaining an insulating effect, e.g. for electrical components
• CPC Class Codes: B29K 2063/00 Use of EP, i.e. epoxy resins or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2995/0003 having particular electrical or magnetic properties, e.g. piezoelectric
• CPC Class Codes: B29L 2031/3061 Number plates
• CPC Class Codes: B29L 2031/7278 Couplings, connectors, nipples B29L2031/7274 takes precedence; for pipes or tubes B29L2031/24; electrical B29L2031/34
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01G 31/02 Oxides
• CPC Class Codes: C01P 2002/72 by d-values or two theta-values, e.g. as X-ray diagram
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C01P 2006/40 Electric properties
• CPC Class Codes: H01H 1/0094 Switches making use of nanoelectromechanical systems [NEMS]

Abstract

The vanadium sesquioxide nanocomposite is useful for applications in thermistors, current switching devices, static charge dissipation devices, and electromagnetic shielding. Vanadium sesquioxide nanoparticles are produced using a sol-gel process that results in a V₂O₅ gel. The gel is heated in a reducing atmosphere of about 5% H2-95% argon at 850° C. for about four hours. The resulting product is dried at about 50° C. for twenty-four hours to produce V₂O₃ powder having particles about 23 nm in size. The nanocomposite is prepared by mixing the sesquioxide nanoparticles with epoxy resin and hardener in a centrifuge, casting the mixture in a Teflon mold, heating the mixture at 60° C. for 30 minutes, and curing the product at 150 KN/m2 at 100° C. for two hours. The nanocomposite contains about 80-90 wt % epoxy resin-hardener mixture and about 10-20 wt % vanadium sesquioxide nanoparticles.

Claims

1. A vanadium sesquioxide nanocomposite, comprising a filler of vanadium sesquioxide (V₂O₃) nanoparticles disposed in a matrix of epoxy.

2. The vanadium sesquioxide nanocomposite according to claim 1, wherein the vanadium sesquioxide nanoparticles have a particle size of about 23 nm.

3. The vanadium sesquioxide nanocomposite according to claim 1, wherein the vanadium sesquioxide nanoparticles are a powder produced by a sol-gel process.

4. The vanadium sesquioxide nanocomposite according to claim 1, wherein the vanadium oxide nanoparticles comprise between about 8% to 20% by weight of an epoxy resin-hardener mixture used to form the epoxy matrix.

5. A thermistor having a positive temperature coefficient of resistivity made from the vanadium sesquioxide nanocomposite according to claim 1.

6. An electrical current switching component made from the vanadium sesquioxide nanocomposite according to claim 1.

7. An antistatic charge dissipation device made from the vanadium sesquioxide nanocomposite according to claim 1.

8. An electromagnetic interference shield for the microwave region between about 1-12 GHz made from the vanadium sesquioxide nanocomposite according to claim 1, wherein the nanoparticles of vanadium sesquioxide comprise about 20% by weight of an epoxy resin-hardener mixture used to form the epoxy matrix.

9. The vanadium sesquioxide nanocomposite according to claim 1, wherein the epoxy matrix is formed from a bisphenol A epoxy resin.

10. A method of making nanoparticles of vanadium sesquioxide in powder form, comprising the steps of:

forming a V₂O₅ gel by sol-gel process;

heating the V₂O₅ gel in a 5% hydrogen-95% argon gas mixture at 850°

C. to form V₂O₃; and

drying the V₂O₃ in vacuum at 50°

C. for 24 hours to obtain the powder.

11. The method of making nanoparticles of vanadium sesquioxide according to claim 10, wherein said heating step is performed for about 4 hours.

12. The method of making nanoparticles of vanadium sesquioxide according to claim 10, wherein the step of forming the V₂O₅ gel by sol-gel process further comprises the steps of:

(a) dissolving V₂O₅ powder in 30% H₂O₂ solution under vigorous magnetic stirring at room temperature;

(b) heating the solution of V₂O₅ powder in H₂O₂ solution at 85°

C. to form red-brown viscous gel; and

(c) controlling pH of the solution at around 2.0 by periodic addition of H₂O₂ during step (b).

13. A vanadium sesquioxide nanocomposite comprising nanoparticles of vanadium sesquioxide formed by the method of claim 10 disposed in an epoxy matrix.

14. A method of forming a vanadium sesquioxide nanocomposite, comprising the steps of:

forming a V₂O₅ gel by sol-gel process;

heating the V₂O₅ gel in a 5% hydrogen-95% argon gas mixture at 850°

C. to form V₂O₃; and

drying the V₂O₃ in vacuum at 50°

C. for 24 hours to obtain a powder containing nanoparticles of vanadium sesquioxide (V₂O₃);

preparing a mixture of epoxy resin and a casting hardener at stoichiometric ratio;

mixing the epoxy resin-hardener mixture with the nanoparticles of 1l vanadium sesquioxide to obtain a nanocomposite mixture;

casting the nanocomposite mixture into a Teflon mold;

heating the Teflon mold containing the nanocomposite mixture at 60°

C.; and

curing the heated nanocomposite mixture at about 100°

C. under a pressure of about 150 KN/m².

15. The method of forming a vanadium sesquioxide nanocomposite according to claim 14, wherein said step of mixing the epoxy resin-hardener mixture with the nanoparticles of vanadium sesquioxide further comprises mixing between about 8% to 20% nanoparticles of the vanadium sesquioxide to between about 92% to 80% of the epoxy resin-hardener by weight.

16. The method of forming a vanadium sesquioxide nanocomposite according to claim 14, wherein the vanadium sesquioxide nanoparticles have a particle size of about 23 nm.

17. The method of forming a vanadium sesquioxide nanocomposite according to claim 14, wherein the step of forming the V₂O₅ gel by sol-gel process further comprises the steps of:

(a) dissolving V₂O₅ powder in 30% H₂O₂ solution under vigorous magnetic stirring at room temperature;

(b) heating the solution of V₂O₅ powder in H₂O₂ solution at 85°

C. to form red-brown viscous gel; and

(c) controlling pH of the solution at around 2.0 by periodic addition of H₂O₂ during step (b).

18. A thermistor having a positive temperature coefficient of resistivity made from the vanadium sesquioxide nanocomposite formed according to the method of claim 14.

19. An electrical current switching component made from the vanadium sesquioxide nanocomposite formed according to the method of claim 14.

20. An electromagnetic interference shield for the microwave region between about 1-12 GHz made from the vanadium sesquioxide nanocomposite formed according to the method of claim 14, wherein the nanoparticles of vanadium sesquioxide comprise about 20% by weight of an epoxy resin-hardener mixture used to form the epoxy matrix.