Casting Mold Binder System for Moisture Resistance
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Solution Overview
Problem
Casting molds produced using inorganic binders like water glass suffer from poor moisture-resistant strength, especially in humid environments, and existing solutions either compromise formability or provide short-term improvements that do not withstand long-term moisture absorption.
Innovation Solution
A method involving a molding material mixture with a water glass binder, carbonate, and borate, where the mixture is cured at temperatures between 120°C-200°C, either in a wet or dry state, to enhance moisture resistance and maintain strength over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If inorganic binder like water glass is used to produce casting mold, then the mold can be formed with good formability, but the moisture-resistant strength deteriorates due to moisture absorption
Solution Approach 1:
The patent uses a composite binder system combining organic binder (polyester resin, phenolic resin, or urea resin) with inorganic binder (water glass) in specific ratios. This composite approach allows the organic binder to provide good formability and initial strength, while the inorganic binder contributes to moisture resistance. The synergistic combination resolves the contradiction between formability and moisture-resistant strength by leveraging the complementary properties of both binder types.
Solution Approach 2:
The patent optimizes the ratio of organic binder to inorganic binder, specifically setting the water glass content to 5-50 parts by mass per 100 parts by mass of organic binder. This parameter optimization ensures that the organic binder provides sufficient formability while the inorganic binder provides adequate moisture resistance, resolving the technical contradiction through precise compositional control.
2Reliability
If particulate metal oxide is added to improve moisture resistance, then the moisture-resistant strength improves, but the formability deteriorates when metal oxide is added in large amounts
Solution Approach 1:
The patent combines multiple binder types (organic and inorganic) rather than relying solely on metal oxide additives. This composite binder system provides moisture resistance through the inorganic water glass component while maintaining formability through the organic binder, avoiding the formability deterioration that occurs when large amounts of metal oxide are added to traditional systems.
Solution Approach 2:
The organic binder acts as an intermediary that bridges the refractory aggregate particles, providing good formability and green strength. This allows the use of inorganic binder for moisture resistance without requiring excessive metal oxide additives that would harm formability, as the organic binder mediates the bonding process during molding.
3Reliability
If conventional additives are used to improve moisture resistance at temperatures of 200°C or lower, then short-term moisture resistance improves, but the strength deteriorates with long-term moisture absorption in highly humid atmosphere
Solution Approach 1:
The patent employs a composite binder system with both organic and inorganic components that work synergistically to provide both short-term and long-term moisture resistance. The inorganic water glass component provides immediate moisture resistance upon curing, while the organic binder maintains structural integrity and prevents strength deterioration during long-term exposure to humid conditions, resolving the time-dependent reliability issue.
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 produces casting molds with improved moisture resistance and long-term preservation capabilities without compromising formability, even in humid conditions.
Implementation Method 1
the molding material mixture is cured, wherein the carbonate and borate (if present) is used in an amount of 1-50 parts by mass with respect to 100 parts by mass of the water glass
Implementation Method 2
a binder including a water glass and (c) a carbonate and/or a borate... so that the molding material mixture is cured
Implementation Method 3
which forming mold is preheated to a temperature of 120°C-200°C, before the refractory aggregate is filled within the forming mold
Data Source
AI summary
Purposes of the present invention are to provide a dry coated sand having a high degree of fluidity at the room temperature, a method of advantageously producing the coated sand, and a method of producing a casting mold having excellent properties, by using the coated sand. The dry coated sand is obtained by mixing an aqueous solution of a water glass used as a binder, with a heated refractory aggregate, whereby water in the aqueous solution is evaporated, and a coating layer of the binder is formed on surfaces of the refractory aggregate. A moisture percentage in the thus obtained dry coated sand is controlled so as to be not more than 0.5% by mass. The intended casting mold is obtained by filling a molding cavity of a forming mold, with the dry coated sand, and passing a steam through the coated sand, to solidify or cure the coated sand.