Search

US-20260125327-A1 - METHOD TO FABRICATE MULTIPHASE ZIRCONIA MATERIAL TO ACHIEVE HIGH FRACTURE TOUGHNESS

US20260125327A1US 20260125327 A1US20260125327 A1US 20260125327A1US-20260125327-A1

Abstract

Yttria-stabilized zirconia ceramic bodies with a composite system comprising two or more phases. The sintered yttria-stabilized zirconia ceramic bodies have localized regions with different yttria concentrations within the composite system. These microregions containing varying yttria concentrations result in a non-uniform distribution of yttria ranges which individually contribute to localized characteristics that synergistically provide improved fracture toughness and machinability.

Inventors

  • Dimple Pradhan
  • Yan Yang
  • Sreeram Balasubramanian

Assignees

  • JAMES R. GLIDEWELL DENTAL CERAMICS, INC.

Dates

Publication Date
20260507
Application Date
20241120

Claims (20)

  1. 1 . A sintered yttria-stabilized zirconia ceramic body comprising a composite system with different localized yttria concentrations within the composite system, wherein more than 50% of the localized yttria concentrations have a yttria concentration of less than 2.5 mol %, more than 55% of the localized yttria concentrations have a yttria concentration of less than 2.8 mol %, less than 40% of the localized yttria concentrations have a yttria concentration greater than 5.8 mol %, less than 30% of the localized yttria concentrations have a yttria concentration greater than 6.5 mol %, and at least 30% of the localized yttria concentrations have a yttria concentration of between 6 and 7.5 mol %, wherein the sintered yttria-stabilized zirconia ceramic body has a fracture toughness of greater than 5, and the wt % is based on the total weight of the yttria-stabilized zirconia at the respective location.
  2. 2 . The ceramic body of claim 1 , wherein the sintered yttria-stabilized zirconia ceramic body has a fracture toughness of greater than 6.8.
  3. 3 . The ceramic body of claim 1 , wherein 100% of the localized yttria concentrations have a yttria concentration of less than 7.5 mol %.
  4. 4 . The ceramic body of claim 2 , wherein 100% of the localized yttria concentrations have a yttria concentration of less than 7.5 mol %.
  5. 5 . The ceramic body of claim 1 , wherein the ceramic body has a bulk yttria concentration of 3.2 wt % to 3.5 mol %.
  6. 6 . The ceramic body of claim 2 , wherein the ceramic body has a bulk yttria concentration of 3.6 wt % to 4 mol %.
  7. 7 . The ceramic body of claim 1 , wherein the ceramic body is a dental prosthetic device.
  8. 8 . The ceramic body of claim 2 , wherein the ceramic body is a dental prosthetic device.
  9. 9 . A sintered yttria-stabilized zirconia ceramic body comprising a composite system with different localized yttria concentrations within the composite system, wherein more than 30% of the localized yttria concentrations have a yttria concentration of less than 2.5 mol %, less than 50% of the localized yttria concentrations have a yttria concentration greater than 5.8 mol %, less than 50% of the localized yttria concentrations have a yttria concentration greater than 6.5 mol %, and at least 35% of the localized yttria concentrations have a yttria concentration of between 6 and 7.5 mol % wherein the sintered yttria-stabilized zirconia body has a fracture toughness of greater than 4, and the mol % is based on the total moles of the yttria-stabilized zirconia at the respective location.
  10. 10 . The ceramic body of claim 9 , wherein 100% of the localized yttria concentrations have a yttria concentration of less than 7.5 mol %.
  11. 11 . The ceramic body of claim 9 , wherein the ceramic body has a bulk yttria concentration of 4 mol % to 4.7 mol %.
  12. 12 . The ceramic body of claim 10 , wherein the ceramic body has a bulk yttria concentration of 4 mol % to 4.7 mol %.
  13. 13 . The ceramic body of claim 9 , wherein the ceramic body is a dental prosthetic device.
  14. 14 . The ceramic body of claim 10 , wherein the ceramic body is a dental prosthetic device.
  15. 15 . A method comprising: mixing a first yttria-stabilized zirconia powder having a yttria concentration of 4 to 8 mol % yttria, based on the total weight of the first powder, with a second yttria-stabilized zirconia powder having a yttria concentration of 2 to 2.6 mol % yttria, based on the total weight of the second powder; forming the resulting mixture into a desired shape, and sintering the shaped mixture resulting in a yttria-stabilized zirconia ceramic body.
  16. 16 . The method of claim 15 , wherein the second yttria-stabilized zirconia powder has a yttria concentration of 2 mol % yttria.
  17. 17 . The method of claim 15 , wherein the first yttria-stabilized zirconia powder has a yttria concentration of 8 mol % yttria and the second yttria-stabilized zirconia powder has a yttria concentration is 2 mol % yttria.
  18. 18 . The method of claim 15 , wherein the first yttria-stabilized zirconia powder has a yttria concentration of 5.3 mol % yttria and the second yttria-stabilized zirconia powder has a yttria concentration is 2 mol % yttria.
  19. 19 . The method of claim 15 , wherein the first yttria-stabilized zirconia powder has a yttria concentration of 4 mol % yttria and the second yttria-stabilized zirconia powder has a yttria concentration is 2 mol % yttria.
  20. 20 . The method of claim 15 , wherein 5 to 70 wt % of the first yttria-stabilized zirconia powder is mixed with 30 to 95 wt % of the second yttria-stabilized zirconia powder, based on the total weight of the mixture.

Description

This application claims the benefit of and priority to U.S. Provisional Patent Application No. 63/602,008, filed Nov. 22, 2023, which is incorporated herein by reference in its entirety. BACKGROUND Yttria-stabilized zirconia (YSZ) has been an attractive material for dental applications due to an excellent combination of properties-esthetics, chemical resistance, mechanical strength and toughness, and biocompatibility. Better esthetics (translucency) and mechanical properties are the key factors to provide the patient with more reliable and natural looking dental restorations. Typically, tetragonal YSZ phase (low-Y2O3 level) provides excellent mechanical properties while cubic YSZ phase (high-Y2O3 level) makes the material more translucent. Currently, most of the existing dental grade zirconia materials have a certain Y2O3 level resulting in a uniform microstructure, which tends to compromise on either mechanical properties or translucency. SUMMARY Disclosed herein are yttria-stabilized zirconia ceramic bodies with a composite system comprising two or more phases. The sintered yttria-stabilized zirconia ceramic bodies have localized regions with different yttria concentrations within the composite system. These microregions containing varying yttria concentrations result in a non-uniform distribution of yttria ranges which individually contribute to localized characteristics that synergistically provide improved fracture toughness and machinability. Also disclosed herein are sintered yttria-stabilized zirconia ceramic bodies comprising a composite system with different localized yttria concentrations within the composite system, wherein more than 55% of the localized yttria concentrations have a yttria concentration of less than 2.5 mol %, at least 10% of the localized yttria concentrations have a yttria concentration between 4 and 5.5 mol %, and at least 90% of the localized yttria concentrations have a yttria concentration of less than 5 mol %, wherein the sintered yttria-stabilized zirconia body has a fracture toughness of greater than 8, and the mol % is based on the total moles of the yttria-stabilized zirconia at the respective location. In some embodiments of the foregoing ceramic bodies, 100% of the localized yttria concentrations have a yttria concentration of less than 5.5 mol %. In some further embodiments, the ceramic bodies have a bulk yttria concentration of 2.8 mol % to 3.1 mol %. In some further embodiments, the ceramic bodies are dental prosthetic devices. Also disclosed herein are sintered yttria-stabilized zirconia bodies comprising a composite system with different localized yttria concentrations within the composite system, wherein more than 45% of the localized yttria concentrations have a yttria concentration of less than 2.5 mol %, at least 30% of the localized yttria concentrations have a yttria concentration of between 4 and 5.5 mol %, more than 60% of the localized yttria concentrations have a yttria concentration of less than 2.8 mol %, and at least 95% of the localized yttria concentrations have a yttria concentration of less than 5 mol %, wherein the sintered yttria-stabilized zirconia ceramic body has a fracture toughness of greater than 6.8, and the mol % is based on the total moles of the yttria-stabilized zirconia at the respective location. In some embodiments of the foregoing ceramic bodies, 100% of the localized yttria concentrations have a yttria concentration of less than 5.5 mol %. In some further embodiments, the ceramic bodies have a bulk yttria concentration of 3.2 mol % to 3.5 mol %. In some further embodiments, the ceramic bodies are dental prosthetic devices. Also disclosed herein are sintered yttria-stabilized zirconia bodies comprising a composite system with different localized yttria concentrations within the composite system, wherein more than 20% of the localized yttria concentrations have a yttria concentration of less than 2.5 mol %, at least 60% of the localized yttria concentrations have a yttria concentration of between 4 and 5.5 mol %, and at least 60% of the localized yttria concentrations have a yttria concentration of less than 5 mol %, wherein the sintered yttria-stabilized zirconia ceramic body has a fracture toughness of greater than 5, and the mol % is based on the total moles of the yttria-stabilized zirconia at the respective location. In some embodiments of the foregoing ceramic bodies, 100% of the localized yttria concentrations have a yttria concentration of less than 5.5 mol %. In some further embodiments, the ceramic bodies have a bulk yttria concentration of 3.6 mol % to 4 mol %. In some further embodiments, the ceramic bodies are dental prosthetic devices. Also disclosed herein are sintered yttria-stabilized zirconia bodies comprising a composite system with different localized yttria concentrations within the composite system, wherein more than 10% of the localized yttria concentrations have a yttria concentration of less than 2.5 mol