Zirconia Sol Particle Shape Control for Precision Polishing
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Solution Overview
Problem
Existing zirconia sols are not suitable as abrasive grains for polishing due to inadequate particle size and shape, leading to suboptimal polishing performance, particularly in precision applications.
Innovation Solution
Zirconia sol with particle diameters between 50 nm and 250 nm and a proportion of distorted particles exceeding 40%, achieved by controlling the concentration and dropwise addition of ammonia water during neutralization of zirconium oxychloride solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional zirconia sol is used with standard particle size and shape distribution, then general polishing application is possible, but polishing rate and surface smoothness are insufficient for precision applications
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle size distribution (D50 between 50-250 nm) and shape distribution (proportion X ≥ 40% distorted particles) of zirconia particles. This is achieved through controlled hydrolysis and condensation reactions with specific molar ratios of ZrOCl2·8H2O to C4H8O2 (0.05-0.5), along with controlling pH (2-7) and temperature (20-100°C) parameters during synthesis, resulting in particles with enhanced polishing performance
Solution Approach 2:
The patent utilizes asymmetry by intentionally producing distorted-shaped zirconia particles (proportion X ≥ 40%) rather than uniform spherical particles. The distorted shape is quantified by the ratio of circumscribed circle diameter to inscribed circle diameter, where particles with ratio ≥ 2.0 are considered distorted. This asymmetric shape enhances cutting ability and polishing rate while maintaining appropriate size control
2Reliability
If zirconia particles with distorted shape are produced to enhance polishing performance, then polishing rate and surface smoothness improve, but particle size control becomes more difficult
Solution Approach 1:
The patent simultaneously controls multiple parameters including molar ratio of ZrOCl2·8H2O to C4H8O2 (0.05-0.5), pH (2-7), temperature (20-100°C), and concentration ratios to achieve the desired balance between distorted shape (proportion X ≥ 40%) and particle size (D50: 50-250 nm). This multi-parameter optimization ensures both polishing performance and size control
Solution Approach 2:
The patent employs feedback control by measuring the proportion of distorted particles (proportion X) and particle size distribution (D50) after synthesis, then adjusting the molar ratio and reaction conditions in subsequent batches to maintain consistent performance. The use of specific molar ratios and controlled reaction conditions provides a feedback mechanism to reproduce the desired particle characteristics
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 resulting zirconia sol exhibits enhanced polishing performance with higher rates and lower surface roughness, making it suitable for precision polishing of materials like semiconductors.
Implementation Method 1
step A of adding ammonia water dropwise to an aqueous zirconium oxychloride solution to neutralize the solution
Implementation Method 2
the concentration of the aqueous zirconium oxychloride solution is 10% by mass or more... to neutralize the solution
Data Source
AI summary
A zirconia sol that has a particle diameter D50 of 50 nm to 250 nm and a proportion X of at least 40% is obtained by the following procedure. (Procedure) A transmission electron microscope image that includes at least 20 isolated particles is obtained. The following operations (1) through (5) are performed on each of the isolated particles. (1) A circumscribed circle and an inscribed circle having the same center as the circumscribed circle are obtained. (2) The ratio of the diameter of the obtained circumscribed circle and the diameter of the obtained inscribed circle is determined. (3) The ratio is determined for all of the isolated particles in the transmission electron microscope image. (4) The number of isolated particles A where the ratio is at least 2.0 is counted. (5) The proportion X of the number of isolated particles A to the total number of isolated particles is determined.