Ceramic Filter Glass Seal Composition for Corrosion Resistance

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Solution Overview

Problem

Current ceramic filters with glass seals suffer from erosion and inadequate corrosion resistance during repeated chemical washing, leading to reduced filtration efficiency and contamination risks.

Innovation Solution

The use of an alkali-free glass with a specific composition, including 20-50 mol% calcia, 1-10 mol% zirconia, 55-65 mol% silica, and minimal zinc oxide, as the glass seal material to prevent alkali component migration and enhance corrosion resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a glass seal is used to cover the end face of the base body, then fluid leakage is prevented and filtration effectiveness is improved, but the glass seal is eroded during repeated chemical washing and corrosion resistance is insufficient

Engineering Contradiction:
Improvefiltration effectivenessVSAvoidcorrosion resistance
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent changes the chemical composition parameters of the glass seal by specifying precise ranges for SiO2 (50-70 wt%), Al2O3 (10-30 wt%), B2O3 (5-20 wt%), and other oxides, while limiting alkali metal oxide content to 1-10 wt%. This parameter optimization enables the glass seal to resist erosion during chemical washing while maintaining sealing effectiveness.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite glass seal material combining multiple oxide components (SiO2, Al2O3, B2O3, CaO, MgO, Na2O, K2O, etc.) in specific proportions. This composite formulation provides both sealing performance and enhanced corrosion resistance, resolving the contradiction between reliability and strength.

Inventive Principle:
Principle #40Composite materials

2Productivity

If chemical washing is performed repeatedly to remove deposited suspended matter, then fluid permeability is recovered, but the glass seal and ceramic porous body are eroded

Engineering Contradiction:
Improvefluid permeabilityVSAvoidstructural integrity
Core Design Contradiction:
ProductivityVSStrength

Solution Approach 1:

The patent applies beforehand cushioning by pre-formulating the glass seal with corrosion-resistant composition before chemical washing begins. The controlled alkali content and specific oxide ratios provide protective buffering against acid and alkali solutions, allowing repeated washing cycles to restore permeability without eroding the seal or base body structure.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 ceramic filter effectively prevents erosion and maintains high corrosion resistance during multiple chemical washing cycles, ensuring consistent filtration performance and preventing contamination.

Implementation Method 1

the alkali component content in glass seal and the difference between the alkali component content of sintering aid used in formation of base body and filter membranes and the alkali component content in glass seal have been controlled in given ranges, whereby erosion of base body and filter membranes in the vicinity of glass seal has been suppressed

Methodology Applied
Scientific EffectAlkali component migration: Diffusion

Data Source

PatentEP1704909B1Ceramic filter
Publication Date: 2010.06.30 NGK INSULATORS LTD
  • EP1704909B1 patent drawingFigure 1~2

AI summary

A ceramic filter has (A) a base body having partition walls made of a ceramic porous body, wherein cells 18 are defined by the partition walls, (B) filer membranes provided on the partition walls, made of a ceramic porous body having an average pore diameter smaller than that of the surface of each partition wall, and (C) a glass seal provided so as to cover at least the end face of the base body, wherein the glass seal is constituted by an alkali-free glass containing silica (SiO2) in an amount of 55 to 65 mol %, zirconia (ZrO2) in an amount of 1 to 10 mol % and at least one kind of alkaline earth metal oxide selected from calcia, baria and strontia but substantially not containing zinc oxide. The ceramic filter can effectively prevent the erosion of the base body and the filter membranes in the vicinity of the glass seal, enables the long-term use of 10 years of more, can withstand chemical washing of a large number of times, and has excellent corrosion resistance.