Method for producing metal and ceramic sintered bodies and coatings

• US 5,590,387 A
• Filed: 10/11/1994
• Issued: 12/31/1996
• Est. Priority Date: 10/27/1993
• Status: Expired due to Term

• Current Assignee: Rudiger Nass
• Original Assignee: HC Starck GmbH (OPUS Investment SARL)
• Inventors: Arpac, Ertugrul, Konig, Theo, Schmidt, Helmut, Albayrak, Sener, Aslan, Mesut, Nass, Rudiger, Fister, Dietmar
• Primary Examiner(s): Jordan, Charles T.
• Assistant Examiner(s): JENKINS, DANIEL J
• Application Number:
  US08/321,416
• Time in Patent Office: 812 Days
• Field of Search: 419/36, 419/38
• US Class Current: 419/36
• CPC Class Codes: B22F 1/052 characterised by a mixture of particles of different sizes or by the particle size distribution
• CPC Class Codes: B22F 1/054 Nanosized particles
• CPC Class Codes: B22F 1/10 Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
• CPC Class Codes: B22F 2998/00 Supplementary information concerning processes or compositions relating to powder metallurgy
• CPC Class Codes: B22F 3/225 by injection molding
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C03C 17/06 with metals C03C17/34, C03C17/44 take precedence
• CPC Class Codes: C03C 17/22 with other inorganic material C03C17/34, C03C17/44 take precedence
• CPC Class Codes: C03C 2217/25 Metals
• CPC Class Codes: C03C 2218/17 from a solid phase
• CPC Class Codes: C04B 2235/3826 Silicon carbides
• CPC Class Codes: C04B 2235/3873 Silicon nitrides, e.g. silicon carbonitride, silicon oxynitride
• CPC Class Codes: C04B 2235/3886 Refractory metal nitrides, e.g. vanadium nitride, tungsten nitride
• CPC Class Codes: C04B 2235/3895 Non-oxides with a defined oxygen content, e.g. SiOC, TiON
• CPC Class Codes: C04B 2235/5454 nanometer sized, i.e. below 100 nm
• CPC Class Codes: C04B 2235/5481 Monomodal
• CPC Class Codes: C04B 2235/6027 Slip casting
• CPC Class Codes: C04B 2235/608 Green bodies or pre-forms with well-defined density
• CPC Class Codes: C04B 2235/6562 Heating rate
• CPC Class Codes: C04B 2235/77 Density
• CPC Class Codes: C04B 2235/781 : Nanograined materials, i.e. having grain sizes below 100 nm
• CPC Class Codes: C04B 35/10 : based on aluminium oxide
• CPC Class Codes: C04B 35/58 : based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides containing free binder metal C22C29/00
• CPC Class Codes: C04B 35/58014 : based on titanium nitrides, e.g. TiAlON
• CPC Class Codes: C04B 35/6263 : characterised by their solids loadings, i.e. the percentage of solids
• CPC Class Codes: C04B 35/6264 : Mixing media, e.g. organic solvents
• CPC Class Codes: C04B 35/628 : Coating the powders or the macroscopic reinforcing agents
• CPC Class Codes: C04B 35/632 : Organic additives
• CPC Class Codes: C04B 41/009 : characterised by the material treated
• CPC Class Codes: C04B 41/4535 : applied as a solution, emulsion, dispersion or suspension
• CPC Class Codes: C04B 41/5068 : Titanium nitride
• CPC Class Codes: C04B 41/87 : Ceramics
• CPC Class Codes: C23C 24/00 : Coating starting from inorganic powder spraying of the coating material in molten state C23C4/00; solid state diffusion C23C8/00 - C23C12/00

Abstract

Metal and ceramic sintered bodies and coatings are produced using a combination of:

(a) nanocrystalline metal or ceramic powder wherein less than 1% of the individual particles have a deviation of more than 40%, and no individual particles have a deviation of more than 60%, from the average grain size, and

(b) at least one low molecular-weight organic compound having at least one functional group that can react and/or interact with groups present on the surface of the powder particles, the materials (a) and (b) being dispersed in water and/or a polar organic solvent as dispersion medium.

Claims

1. Method for producing metal and ceramic sintered bodies or coatings comprising:

(a) nanoscale ceramic or metal powder particles wherein less than 1% of the individual particles have a deviation of more than 40%, and essentially no individual particles have a deviation of more than 60%, from the average grain size, and

(b) at least one low molecular-weight organic compound having at least one functional group that reacts and/or interacts with groups present on the surface of the powder particles, the materials (a) and (b) being dispersed in water and/or a polar organic solvent as dispersion medium;

the method comprising the further steps of removing the dispersion medium, forming the surface-modified ceramic or metal powder, before or after the removal of the dispersion medium, to a green body or coating and sintering such green body or coating.

2. Method according to claim 1, characterized in that less than 1% of the individual particles have a deviation of more than 20% and no individual particles have a deviation of more than 50% from the average grain size.

3. Method according to either of claims 1 or 2, characterized in that less than 1% of the individual particles have a deviation of more than 10% and no individual particles have a deviation of more than 40% from the average grain size.

4. Method according to either of claims 1 or 2, characterized in that the metal and/or ceramic powders are selected from the group consisting of carbides, nitrides, borides, silicides, phosphites, sulfides, oxides and/or combinations thereof of the elements B, Al, Si, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, La, Y, Fe, Co, Ni alone or in combination with one another.

5. Method according to either of claims 1 or 2, characterized in that fine-particulate powders of the metals selected from the group consisting of Fe, Co, Ni, W and Mo, with a defined particle size between 1.0 nm and less than 100 nm, are used as metal powder.

6. Method according to either of claims 1 or 2, characterized in that fine-particulate powders of the metals selected from the group consisting of B, Al, Si, Ti, Zr, Hf, V, Nb, Ta und Cr, with a defined particle size between 1.0 nm and 3 μ

m, are used as metal powder.

7. Method according to either of claims 1 or 2, characterized in that fine-particulate non-oxide ceramic powders MeX, wherein Me is selected from the group consisting of B, Al, Si, Ti, Zr, Hf, V, Ta, Nb, Mo, W, La, Fe, Co, Ni and Cr and combinations thereof and X is selected from the group consisting of C, N, B, Si and combinations thereof, with the exception of Si₃ N₄ larger than 100 mn and AlN larger than 200 nm, are used as ceramic powder.

8. Method according to claim 7, characterized in that the ceramic powders have an oxygen content of less than 5,000 ppm.

9. Method according to claim 8, characterized in that the oxygen content is less than 1,000 ppm.

10. Method according to claim 8, characterized in that the oxygen content is less than 50 ppm.

11. Method according to either of claims 1 or 2 wherein metal powders are used and they have an oxygen content of less than 5,000 ppm.

12. Method according to claim 11, characterized in that the oxygen content is less than 1,000 ppm.

13. Method according to claim 11, characterized in that the oxygen content is less than 50 ppm.

14. Method according to claim 1, characterized in that fine-particulate oxide ceramic powders of metal oxides are used, wherein the metal is selected from the group consisting of Al, Si, Zr, Hf, Ta, Nb, Mo, W, V, La, Y and combinations, the Al₂ O₃ being present in the α

-phase and the SiO₂ being present in crystalline form.

15. Method according to claim 7, characterized in that the total of the impurities of the ceramic powders, with the exception of oxidic impurities, is less than 5,000 ppm.

16. Method according to claim 15, characterized in that the total of the impurities, with the exception of the oxidic impurities, is less than 1,000 ppm.

17. Method according to claim 16, characterized in that the total of the impurities, with the exception of the oxidic impurities, is less than 200 ppm.

18. Method according to claim 1, characterized in that the surface-modified metal or ceramic powder is sintered at a temperature which is 0.4 to 0.6 of the melting point or decomposition point.

19. Method according to claim 1, characterized in that the low molecular-weight organic compound has a molecular weight of not more than 1,000, in particular not more than 500.

20. Method according to either of claims 1 or 19, characterized in that the low molecular-weight organic compound is selected from the group consisting of aliphatic compounds;

saturated or unsaturated C₁ -C₁₂ monocarboxylic acids, polycarboxylic acids;

amines of the formula R_3-n NH_n, wherein n=0, 1 or 2 and the residue R, independently of one another, represent alkyl groups with 1 to 12 carbon atoms;

β

-carbonyl compounds with 4 to 12;

titanic acid esters;

alcoholates and organoalkoxysilanes.

21. Method according to claim 20, wherein R is an AlYl group with 1 to 6 carbon atoms.

22. Method according to claim 20, wherein the dicarbonyl compound has 5 to 8 carbon atoms.

23. Method according to claim 20, characterized in that the dispersion medium comprises a mixture of water and a polar organic solvent.

24. Method according to claim 20, characterized in that 20 to 90, based on the total weight of dispersion medium, ceramic or metal powder and low molecular-weight organic compound, is used.

25. Method according to claim 24, wherein 30 to 80 wt.-% of dispersion medium is used.

26. Method according to claim 20, characterized in that the weight ratio of ceramic or metal powder/low molecular-weight organic compound is 1000:

1 to 4;

1.

27. Method according to claim 26, wherein the powder/organic compound weight ratio is in the range from 500:

1 to 8;

1.

28. Method according to claim 1, characterized in that the dispersion is carried out at a temperature of 20°

C. up to the boiling point of the dispersion medium.

29. Method according to claim 28, wherein the dispersion medium is refluxed.

30. Method according to claim 1, characterized in that the dispersion medium is removed by freeze drying or freeze spray drying.

31. Method according to claim 1, characterized in that the surface-modified ceramic or metal powder is redispersed in another medium after the separation therefrom of the dispersion medium.

32. Method according to claim 1 characterized in that the ceramic powder particles comprise a compound of Ti.

33. Method according to claim 1 characterized in that the ceramic powder particles comprise TiN.

34. Method according to claim 1 characterized in that the ceramic powder particles comprise TiN/SiC, where TiN is the major component.

35. Method according to claim 1 characterized in that the ceramic powder particles comprise TiN/Si₃ N₄, where TiN is the major component.