High-Porosity Vitrified Grinding Stone via Freeze-Drying
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Solution Overview
Problem
Existing methods for producing high-porosity vitrified grinding stones result in unstable shape and deformation due to independent pores, leading to accumulation of swarf and reduced grinding performance.
Innovation Solution
A method involving a grinding-stone raw material slurry with a gelling agent, abrasive grains, and vitrified bond, where the mixture is gelled, frozen particles are generated, and then sublimated under vacuum to create communicating pores, followed by firing to bind the abrasive grains, forming strong bond bridges without resin coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If organic pore-forming agent is used to create high porosity, then porosity is improved, but pores become independent closed pores causing swarf accumulation
Solution Approach 1:
The patent uses ice particles as a pore-forming agent that sublimates during freeze-drying to create a porous structure. The key innovation is that the ice particles create interconnected pores rather than closed pores, allowing swarf to be ejected during grinding while maintaining high porosity (60-90%).
Solution Approach 2:
The patent employs phase transition of water to ice and then sublimation back to vapor during freeze-drying. This phase transition process creates a controlled porous structure where ice particles form a scaffold that is later removed, leaving interconnected pores that prevent swarf accumulation.
2Quantity of substance
If meringue-like foam material is used to achieve high porosity, then porosity is improved, but molded body shrinks due to bond bridge deformation
Solution Approach 1:
The patent uses freezing of the slurry to generate ice particles within the molded body. This phase transition occurs before drying, creating a rigid ice scaffold that maintains the molded body's shape during subsequent vacuum drying, preventing shrinkage and deformation.
Solution Approach 2:
The patent performs freezing before vacuum drying to pre-establish a rigid structure. The ice particles formed in advance act as temporary support structures that prevent bond bridge deformation during the drying process, ensuring shape stability.
3Strength
If resin coating is applied to increase strength, then strength is improved, but manufacturing complexity increases
Solution Approach 1:
The patent changes the porosity parameter to an optimal range (60-90%) and controls the pore structure to be interconnected. This parameter optimization allows the vitrified bond itself to provide sufficient strength without requiring additional resin coating, thereby reducing manufacturing complexity.
Solution Approach 2:
The patent enables the vitrified bond to provide its own strengthening function through optimized composition and processing. The bond formulation and firing conditions are adjusted so that the bond bridges themselves become sufficiently strong, eliminating the need for external resin coating reinforcement.
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 method stabilizes the grinding stone production, maintains high porosity, and enhances grinding efficiency and strength by suppressing shrinkage and forming strong bond bridges, achieving a pore volume ratio of 65-90% and specific gravity of 0.34-1.48, suitable for semiconductor wafer grinding.
Implementation Method 1
a grinding-stone raw material slurry that is a mixture fluid of abrasive grains, a vitrified bond and a water, such that a gellable water-soluble polymer is dissolved in the mixture fluid; a molding step of obtaining a molded body, by gelling the grinding-stone raw material slurry
Implementation Method 2
a freeze vacuum drying step of generating a plurality of frozen particles inside the molded body by freezing the molded body after the molding step
Implementation Method 3
placing the molded body under a vacuum state, so as to sublimate the frozen particles generated inside the molded body for thereby drying the molded body
Implementation Method 4
a firing step of obtaining the high-porosity vitrified grinding stone, by binding the abrasive grains with the vitrified bond by firing the molded body after the freeze vacuum drying step
Data Source
AI summary
A method for producing a high-porosity vitrified grinding stone that has a plurality of pores communicating with each other. The method includes: (a) a grinding-stone-material preparing step of obtaining a grinding-stone raw material slurry that is a mixture fluid of abrasive grains, a vitrified bond, a gellable water-soluble polymer and a water; (b) a molding step of obtaining a molded body, by gelling the grinding-stone raw material slurry with use of a molding mold; (c) a freeze vacuum drying step of generating a plurality of frozen particles inside the molded body by freezing the molded body, and placing the molded body under a vacuum state, so as to sublimate the frozen particles generated inside the molded body for thereby drying the molded body; and (d) a firing step of obtaining the high-porosity vitrified grinding stone, by binding the abrasive grains with the vitrified bond by firing the molded body.