Joining of advanced materials by plastic deformation

• US 20070187464A1
• Filed: 12/12/2006
• Published: 08/16/2007
• Est. Priority Date: 08/07/2001
• Status: Active Grant

• Current Assignee: UChicago Argonne LLC
• Original Assignee: UChicago Argonne LLC
• Inventors: Singh, Dileep, Routbort, Jules, Gutierrez-Mora, Felipe, Goretta, Kenneth
• Granted Patent: US 7,722,731 B2
• Time in Patent Office: Days
• US Class Current: 228/101
• CPC Class Codes: C04B 2237/064 based on alumina or aluminates
• CPC Class Codes: C04B 2237/068 based on refractory oxides, e.g. zirconia
• CPC Class Codes: C04B 2237/121 based on aluminium
• CPC Class Codes: C04B 2237/122 based on refractory metals
• CPC Class Codes: C04B 2237/123 based on iron group metals, e.g. steel
• CPC Class Codes: C04B 2237/34 Oxidic
• CPC Class Codes: C04B 2237/343 Alumina or aluminates
• CPC Class Codes: C04B 2237/348 Zirconia, hafnia, zirconates or hafnates
• CPC Class Codes: C04B 2237/36 Non-oxidic
• CPC Class Codes: C04B 2237/402 Aluminium
• CPC Class Codes: C04B 2237/405 Iron metal group, e.g. Co or Ni
• CPC Class Codes: C04B 2237/58 Forming a gradient in composition or in properties across the laminate or the joined articles
• CPC Class Codes: C04B 35/645 Pressure sintering
• CPC Class Codes: C04B 37/001 directly with other burned ceramic articles
• CPC Class Codes: C04B 37/005 consisting of glass or ceramic material
• CPC Class Codes: C04B 37/026 consisting of metals or metal salts
• CPC Class Codes: Y10T 156/10 Methods of surface bonding and/or assembly therefor

Abstract

A method for utilizing plastic deformation resulting from grain boundary sliding with or without a novel joint compound that leads to the joining of advanced ceramic materials, intermetallics, and cermets. A joint formed by this approach is as strong as or stronger than the materials joined. The method does not require elaborate surface preparation or application techniques. The method also allows for the formation of transparent joints between two subunits of a construct joined via plastic deformation. The method can be used to tailor residual stresses and maintain native porosity.

Claims

1. A method for the fabrication of constructs containing preselected regions of residual stress, the method comprising:

a) selecting constituents of the construct which exhibit grain boundary sliding at temperatures below 0.7 times the melting point temperature of the lowest melting point constituent;

b) assembling the constituents to form a loosely assembled construct, and wherein a first subunit with a first coefficient of thermal expansion contacts a second subunit with a second coefficient of thermal expansion; and

c) compressing the loosely assembled construct for a time and at a temperature to cause grain boundary sliding between constituents comprising the first and second subunits to form a rigid construct.

2. The method as recited in claim 1 wherein the step of assembling the subunits further comprises directly contacting a surface of the first subunit with a surface of the second subunit.

3. The method as recited in claim 1 wherein the step of assembling the subunits further comprises a joint compound positioned intermediate the first subunit and the second subunit.

4. The method as recited in claim 3 wherein at least one of the subunits contains metal.

5. The method as recited in claim 3 wherein at least one of the subunits contain metal and the metal contains an oxide layer which comprises the joint compound.

6. The method as recited in claim 3 wherein at least one of the subunits contains metal and the metal is oxided to form an oxide interlayer positioned intermediate the first subunit and the second subunit.

7. The method as recited in claim 1 wherein the step of compressing the loosely assembled construct further comprises subjecting the construct to a pressure selected from 5 MPa to 100 MPa.

8. The method as recited in claim 1 wherein the subunits exhibit native porosity and the rigid construct exhibits said native porosity.

9. The method as recited in claim 1 wherein the subunits exhibit a first optical transparency and the rigid construct exhibits said optical transparency.

10. The method as recited in claim 1 wherein the temperature is 70 percent of the melting point of the lowest melting point constituent among the constituents.

11. The method as recited in claim 1 wherein a single temperature and compressive force is utilized.

12. The method as recited in claim 1 wherein the coefficients of thermal expansion of the constructs to be joined are selected such that the residual stresses resulting from the differences in thermal expansion coefficients resist fracture.

13. A construct produced by the method recited in claim 12, wherein the first subunit comprises LaSrMnO₃ and the second subunit comprises yittria stabilized zirconia.

14. A method for fabricating optically transparent constructs, the method comprising:

supplying subunits exhibiting predetermined transparency; and

pressing the subunits against each other to form an interface, whereby plastic deformation occurs between the units at the interface while maintaining the predetermined transparency at the interface.

15. The method as recited in claim 14 wherein the subunits comprise polycrystalline material selected from the group consisting of MgF₂, TiO₂, ZnS, MgO, GaN, ZnSe, GaAs, and combinations thereof.

16. The method as recited in claim 14 wherein the subunits comprise materials having grain sizes of from 0.3 microns to 20 microns.

17. The method as recited in claim 14 wherein the subunits are pressed against each other at strain rates between 10⁻

7 s<sup>−

1</sup> and 10<sup>−

3</sup> s<sup>−

1</sup>.

18. The method as recited in claim 14 wherein the subunits are pressed against each other for a time between 3 minutes and 500 minutes.

19. The method as recited in claim 14 wherein grain-boundary sliding occurs between particles comprising the subunits.