LiF-Coated Yttria for Uniform Sintering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional processing of polycrystalline yttria results in high scattering and absorption losses due to inhomogeneous distribution of sintering aids, leading to poor yield, high costs, and limited size and shape manufacturing capabilities, as well as issues with optical uniformity and transparency.
Innovation Solution
LiF-coated yttria particles with a continuous fluoride salt coating are used to ensure uniform sintering and reduce porosity, achieved through a process involving mixing yttria cores with a fluoride salt solution, spraying into a drying column to form a coating, and subsequent heating to remove impurities, resulting in a dense and highly transparent ceramic product.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sintering aids are mechanically mixed with yttria powder, then sintering can be achieved, but inhomogeneous distribution of sintering aids occurs leading to high scattering and absorption losses
Solution Approach 1:
The sintering aid (LiF) is pre-coated onto the yttria powder particles before sintering. This preliminary action ensures uniform distribution of the sintering aid on the particle surfaces, eliminating the inhomogeneity problem associated with mechanical mixing while maintaining sintering capability.
Solution Approach 2:
A coating process is introduced as an intermediary step between powder preparation and sintering. The coating acts as a mediator that uniformly distributes the sintering aid on particle surfaces, preventing direct particle-particle contact and ensuring homogeneous distribution throughout the compact.
2Quantity of substance
If dense polycrystalline yttria is produced through traditional sintering, then material consolidation is achieved, but high scattering sites and absorption regions are formed
Solution Approach 1:
The patent applies local quality by coating LiF specifically on the particle surfaces where it is needed for sintering, while keeping the particle interiors free of contaminants. This localized application ensures dense consolidation at grain boundaries without introducing scattering sites within the grain interiors.
Solution Approach 2:
The patent changes the chemical composition parameters by using LiF-coated yttria powder with controlled LiF content (0.1-5 wt%). This parameter control ensures sufficient sintering aid for densification while preventing excessive reactions that would create scattering sites and absorption regions.
3Productivity
If larger samples are manufactured, then production scale is increased, but inhomogeneity in sintering aid distribution becomes more pronounced
Solution Approach 1:
The sintering aid is pre-coated on particles before large-scale processing. This preliminary coating ensures uniform distribution is achieved at the particle level, which scales effectively to large samples without the inhomogeneity problems that plague mechanical mixing approaches in large batches.
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 LiF-coated yttria particles significantly reduce scattering sites and absorption losses, enabling the production of dense, transparent, and optically uniform polycrystalline yttria ceramics with improved manufacturing capabilities and reduced costs, suitable for applications in high-power lasers and transparent windows.
Implementation Method 1
a fluoride salt coating on the yttria core, the coating being sufficiently continuous to prevent a large number of sites where a second yttria core may come into contact with the first yttria core
Implementation Method 2
The particle has been heated in an oxidizing atmosphere to a temperature in the range of about 400° C. to about 750° C.
Implementation Method 3
The particle has been heated in an oxidizing atmosphere to a temperature in the range of about 400° C. to about 750° C.
Data Source
AI summary
An embodiment of the invention includes a particle. The particle includes a first yttria core; and a fluoride salt coating on the first yttria core. The coating is sufficiently continuous to prevent a large number of sites where a second yttria core may come into contact with the first yttria core. Optionally, the particle has been heated in an oxidizing atmosphere to a temperature in the range of about 400° C. to about 750° C. Optionally, the particle is substantially free of at least one of carbon-containing species and water. Optionally, the fluoride salt is lithium fluoride. Optionally, the fluoride salt is aluminum fluoride.