Ceramic Particulate Filter End-Face Coating Against DEF Damage
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Solution Overview
Problem
Exhaust components, particularly particulate filters, are susceptible to damage from exposure to reducing agents like DEF and its byproducts, leading to contamination and structural degradation in non-ideal exhaust system configurations.
Innovation Solution
Applying a metal oxide coating, such as alumina, to the end face region of ceramic honeycomb bodies in particulate filters to prevent penetration of DEF byproducts and mitigate damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a particulate filter is used in non-ideal exhaust system configurations, then the filter can treat exhaust flows, but the filter becomes susceptible to damage from reducing agents like DEF and its byproducts
Solution Approach 1:
A metal oxide coating layer is applied to the ceramic honeycomb walls to serve as an intermediary protective barrier. This coating prevents direct contact between harmful reducing agents (DEF and its byproducts) and the ceramic substrate, thereby protecting the filter structure while allowing exhaust treatment functionality to continue
Solution Approach 2:
The filter structure is transformed from a single-material ceramic honeycomb to a composite structure with ceramic substrate and metal oxide coating. This composite design combines the high-temperature stability of ceramic with the chemical resistance of metal oxide, creating a more durable filter that can withstand exposure to reducing agents
2Reliability
If the filter structure is reinforced with metal oxide coating, then resistance to reducing agent damage improves, but manufacturing complexity increases
Solution Approach 1:
The metal oxide coating is applied by controlling deposition parameters such as coating thickness (micrometer level), metal oxide composition ratios, and application temperature. By optimizing these parameters, the coating provides maximum protection with minimal material and process complexity
Solution Approach 2:
The metal oxide coating is applied as a porous layer that maintains the underlying ceramic honeycomb porosity. This porous structure allows exhaust gases to permeate through while the coating provides the protective barrier, avoiding the need for dense, complex structures that would impede flow
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 alumina coating effectively prevents damage to the filter's structure and porosity, maintaining its functionality and reducing pressure drop across the filter.
Implementation Method 1
the alumina particles are present to a depth extending axially into the honeycomb structure of 0.01 to 2.0 inches from the first transverse face
Implementation Method 2
a first transverse face at the first end comprises metal oxide particles affixed to only an end portion of the intersecting walls
Data Source
AI summary
An exhaust treatment apparatus for treating exhaust gas flowing through an exhaust line housing from an upstream location to a downstream location in a downstream direction, the exhaust treatment apparatus comprising a ceramic filter body having a honeycomb structure of a plurality of intersecting porous ceramic walls extending from a first end to a second end in an axial direction and defining a plurality of channels extending in the axial direction, wherein a first transverse face at the first end comprises metal oxide particles affixed to a portion of the intersecting walls. The metal oxide particles may be affixed to the upstream end, or the downstream end, or both the upstream and downstream ends. Preferably the metal oxide particles provide reinforcement to the underlying portion of the walls, and of the honeycomb structure itself.