Ceramic Injection Molding Binder System for Defect-Free Sintering
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Solution Overview
Problem
Conventional solvent-debinding methods for ceramic powders with small particle sizes face challenges such as swelling and cracking, especially when producing green bodies with complex shapes, which hinders the production of high-density ceramic sintered bodies.
Innovation Solution
A composition for molding comprising 30 to 70% by volume of a sinterable ceramic powder with an average particle size of 1 μm or less and 30 to 70% by volume of an organic binder, which includes a thermoplastic resin (A) not melting or swelling in an organic solvent, a thermoplastic resin (B) with a polar group, and an organic compound (C) with a melting point of 70° C. or less, is used. This composition undergoes injection molding or extrusion molding, followed by solvent-debinding with solvents like acetone or alcohol, and subsequent thermal-debinding to produce a ceramic sintered body without defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional solvent-debinding methods are used for ceramic powders with small particle sizes (1 μm or less), then the green body can be formed, but swelling and cracking occur during solvent-debinding especially for complex shapes
Solution Approach 1:
The organic binder is segmented into multiple functional components: a water-soluble binder (30-70 wt%) that can be extracted by water, and a thermoplastic resin (70-30 wt%) that provides structural support. This segmentation allows selective removal of the water-soluble binder component without compromising the structural integrity provided by the thermoplastic resin during the debinding process.
Solution Approach 2:
Water is used as an intermediary extracting solvent instead of organic solvents. The water-soluble binder component acts as an intermediary that can be selectively removed by water, preventing the swelling and cracking issues that occur with conventional organic solvent-debinding methods while enabling effective binder removal.
2Loss of substance
If water is used as the extracting solvent for debinding, then organic binder removal is achieved, but drying time increases due to water's high boiling point (100°C)
Solution Approach 1:
The invention changes the chemical composition parameters of the organic binder system by incorporating a water-soluble binder component. This parameter change enables the use of water as the extracting solvent, which虽然 has a higher boiling point, but allows for more efficient binder removal through water solubility, offsetting the longer drying time concern.
3Ease of manufacture
If a water-soluble binder is used for molding, then binder removal by water extraction is enabled, but flowability and strength deteriorate due to high moisture absorption rate
Solution Approach 1:
The organic binder is formulated as a composite material system combining a water-soluble binder (30-70 wt%) with a thermoplastic resin (70-30 wt%). The thermoplastic resin component compensates for the moisture absorption issues of the water-soluble binder, maintaining green body strength and flowability while enabling water extraction for binder removal.
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 enables the production of ceramic sintered bodies with high density and without defects such as swelling or cracking, even for complex shapes, thereby achieving a sound sintered body in a short time.
Implementation Method 1
an organic compound (C) to be dissolved in an organic solvent and having a melting point of 70° C. or less
Implementation Method 2
the added organic binder is to be removed by heating
Data Source
AI summary
A composition for molding and a method for producing a ceramic sintered body which enable production of a sound debound body without bubbles, swelling, or cracking therein. The method uses a composition for molding containing 30 to 70% by volume of a ceramic powder and 30 to 75% by volume of an organic binder. The method includes the steps of: preparing a green body from the composition by using an injection molding machine or an extrusion molding machine; solvent-debinding the organic compound (C) in an amount equivalent to 30% by volume or more of the organic binder in the composition for molding, at a temperature of 40° C. or more and 80° C. or less with a solvent; heating the green body after the solvent-debinding to debinder the remaining organic binder; and sintering the ceramic green body.