Monoclinic Zirconia Composition for Fast Sintering and Translucency

Solution Overview

Problem

Existing zirconia sintered bodies face challenges in processing to desired shapes due to high shrinkage factors and prolonged firing times, which affect production efficiency and translucency, particularly in dental applications.

Innovation Solution

A zirconia composition with 55% monoclinic phase and a stabilizer that suppresses phase transition, combined with controlled firing temperatures and reduced retention times, to produce pre-sintered and sintered bodies with enhanced translucency and accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If prolonged firing time (2 hours at highest temperature) is used to maintain translucency, then translucency is improved, but production efficiency deteriorates and energy costs increase

Engineering Contradiction:

ImprovetranslucencyVSAvoidproduction efficiency

Core Design Contradiction:

Illumination intensityVSProductivity

Solution Approach 1:

The patent changes the crystal phase composition parameter of zirconia powder to predominantly monoclinic phase (55% or more) with controlled particle size (0.06-0.17 μm average diameter), which fundamentally alters the sintering behavior and enables shortened firing time while maintaining translucency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes the monoclinic phase transition characteristics of zirconia, where the predominantly monoclinic phase composition enables controlled phase transformation during sintering that achieves desired translucency with significantly reduced holding time at peak temperature

Inventive Principle:

Principle #36Phase transitions

2Illumination intensity

If prolonged firing time (2 hours at highest temperature) is used to maintain translucency, then translucency is improved, but energy costs increase

Engineering Contradiction:

ImprovetranslucencyVSAvoidenergy costs

Core Design Contradiction:

Illumination intensityVSUse of energy by stationary object

Solution Approach 1:

The patent changes the crystal phase composition parameter of zirconia powder to predominantly monoclinic phase (55% or more) with controlled particle size (0.06-0.17 μm average diameter), which fundamentally alters the sintering behavior and enables shortened firing time while maintaining translucency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes the monoclinic phase transition characteristics of zirconia, where the predominantly monoclinic phase composition enables controlled phase transformation during sintering that achieves desired translucency with significantly reduced holding time at peak temperature

Inventive Principle:

Principle #36Phase transitions

3Use of energy by stationary object

If high shrinkage factor is accepted to reduce firing temperature, then energy costs decrease, but manufacturing precision deteriorates

Engineering Contradiction:

Improveenergy costsVSAvoidshrinkage control accuracy

Core Design Contradiction:

Use of energy by stationary objectVSManufacturing precision

Solution Approach 1:

The patent changes the crystal phase composition parameter of zirconia powder to predominantly monoclinic phase (55% or more) with controlled particle size (0.06-0.17 μm average diameter), which reduces shrinkage variability and improves dimensional control during sintering

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces reliance on mechanical dimensional control with chemical-phase-based control, where the monoclinic phase composition and particle size distribution inherently control shrinkage behavior, reducing sensitivity to temperature variations

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

This approach reduces shrinkage variability, enhances production efficiency, and maintains high translucency while shortening manufacturing time, benefiting dental prosthesis production by reducing patient wait times and energy costs.

Implementation Method 1

a stabilizer capable of suppressing phase transition of zirconia

Methodology Applied

Scientific EffectPhase transition suppression:

Implementation Method 2

firing a pressed body of the zirconia powder under the condition of 1450° C., at a temperature-raising rate of 600° C./hr and a retention time of 2 hours

Methodology Applied

Scientific EffectSintering: Sintering

Implementation Method 3

Zirconia is a compound in which phase transition occurs among a plurality of crystal systems

Methodology Applied

Scientific EffectPhase transition: Phase Change

Data Source

PatentUS12559427B2Zirconia composition, pre-sintered body and sintered body, and method of producing the same

Publication Date: 2026.02.24 KURARAY NORITAKE DENTAL

AI summary

A composition comprises a zirconia powder, in which 55% or more thereof is monoclinic, and a stabilizer capable of suppressing phase transition of zirconia. An average particle diameter of zirconia particles and particles of the stabilizer is 0.06 μm to 0.17 μm. At least a portion of the stabilizer does not form a solid solution with zirconia.