Y2O3-Stabilized Zirconia Sintering for Hydrothermal Stability
Solution Overview
Problem
Current methods for producing aging-resistant Y 2 O 3 -stabilized zirconium oxide ceramic sintered bodies are costly and inefficient, as they rely on expensive nanopowders and result in reduced translucency due to the addition of Al 2 O 3, which compromises mechanical properties and hydrothermal stability.
Innovation Solution
A cost-effective method involving the use of commercial sub-micron powders with a specific comminution process using small grinding media in an agitator ball mill to achieve a narrow particle size distribution, followed by slip casting and sintering at optimized temperatures, achieving high sintered density and stability against hydrothermal aging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nanopowders with particle size below 100 nm are used to produce aging-resistant ceramic, then hydrothermal stability is improved, but manufacturing cost increases significantly
Solution Approach 1:
The patent changes the particle size parameter from sub-100 nm nanopowder to sub-micrometer powder (0.1-10 μm), which maintains adequate hydrothermal stability while dramatically reducing material cost and improving ease of manufacture. This parameter shift allows using commercially available powders instead of expensive nanopowders.
Solution Approach 2:
The patent applies preliminary comminution treatment using an agitator ball mill with small grinding media (0.1-1 mm) to reduce particle size and break down agglomerates before shaping. This preliminary size reduction achieves the necessary fine particle distribution without requiring expensive nanopowders as starting material.
2Reliability
If Al 2 O 3 is added to increase hydrothermal stability, then aging resistance is improved, but translucency deteriorates due to light scattering
Solution Approach 1:
The patent removes Al 2 O 3 additive from the composition entirely, relying instead on the intrinsic properties of Y 2 O 3 -stabilized zirconium oxide and the refined particle size distribution to achieve hydrothermal stability. This extraction eliminates the light scattering effect that Al 2O3 causes, preserving translucency.
Solution Approach 2:
The patent changes the compositional parameter by eliminating Al 2O3 addition and instead optimizing the Y 2O3 stabilizer content and particle size parameters. This compositional simplification maintains aging resistance through controlled phase transformation while preserving optical properties.
3Reliability
If stabilizer content is increased to improve hydrothermal stability, then aging resistance is improved, but mechanical strength deteriorates
Solution Approach 1:
The patent optimizes the stabilizer content parameter, using Y 2O3 concentrations in the range of 2-5 mol% rather than higher amounts. This optimized parameter range achieves adequate hydrothermal stability while preserving the transformation strengthening mechanism that provides high mechanical strength.
Solution Approach 2:
The patent applies preliminary particle size reduction and agglomerate breakdown through agitator ball milling, which creates a narrow particle size distribution. This preliminary action ensures homogeneous stabilizer distribution and fine microstructure, achieving aging resistance through refined microstructure rather than excessive stabilizer content, thereby preserving mechanical strength.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method produces ceramic sintered bodies with enhanced hydrothermal stability, maintaining high mechanical strength and translucency, suitable for applications in medical implants, engine components, and dental frameworks, with reduced monoclinic phase conversion and increased sintered density.
Implementation Method 1
a specific comminution process using small grinding media in an agitator ball mill
Implementation Method 2
followed by slip casting
Implementation Method 3
sintering at optimized temperatures, achieving high sintered density
Implementation Method 4
the tetragonal phase transforms into the monoclinic phase before fracture of the material occurs. Fracture energy is consumed and compressive stresses are induced in the material
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention relates to a shaped sintered ceramic body which contains Y2O3-stabilized zirconium oxide, has a sintered density of at least 99% of the theoretical sintered density and is characterized in that the shaped sintered body has an average grain size of < 180 nm and the zirconium oxide fraction of the shaped sintered body consists of tetragonal phase and cubic phase. The shaped sintered body is stable to hydrothermal ageing at 134°C and 2 bar in a water vapour atmosphere for at least 120 hours. The invention further relates to a process for producing a shaped sintered ceramic body containing a Y2O3-stabilized zirconium oxide, which comprises the steps: dispersing a submicron powder; comminuting the dispersed submicron powder, where the submicron powder having a diameter of equal to or less than 100 mum is comminuted by means of milling media to a particle size d95 < 0.42 mum; shaping the dispersion to form a body and sintering the body to give the shaped sintered body. The shaped sintered body of the invention can be used for implants, linings of industrial plants and for industrial components which can be subject to hydrothermal ageing.