Insulating Layer Barium Glass Adhesion Exhaust Gas Treatment
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Solution Overview
Problem
Existing tubular members for exhaust gas treatment devices face issues with electric leakage and poor adhesiveness between the metal tubular body and insulating layers, leading to decreased purification performance, particularly due to the peeling of insulating layers under thermal cycling.
Innovation Solution
A tubular member with a metal body and an insulating layer containing glass with a high barium content, along with lanthanum and zinc, which exhibits excellent adhesiveness through a peeling test involving thermal cycling, forming a stable interface that prevents electric leakage and maintains insulation even under high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulating layer is formed on the inner peripheral surface of the metal tubular body, then electric leakage is prevented, but the insulating layer peels off under thermal cycling conditions
Solution Approach 1:
The patent changes the chemical composition parameters of the glass in the insulating layer by specifying precise ranges for SiO2 (60-80 mol%), B2O3 (10-30 mol%), and MgO (5-20 mol%). This compositional adjustment optimizes the thermal expansion coefficient and chemical compatibility between the glass and metal tubular body, preventing peeling during thermal cycling while maintaining electrical insulation properties.
Solution Approach 2:
The patent creates a composite material system combining metal tubular body with a specifically formulated glass insulating layer. The glass composite contains multiple oxides (SiO2, B2O3, MgO, Al2O3, CaO, Na2O, K2O) in controlled proportions, forming a heterogeneous structure that leverages the electrical insulation of glass while achieving thermal compatibility with the metal substrate through careful compositional design.
2Reliability
If the insulating layer is made thicker to improve insulation, then electric leakage prevention is enhanced, but manufacturing complexity and cost increase
Solution Approach 1:
The patent optimizes the thickness parameter of the insulating layer to a specific range (50-500 μm, preferably 100-300 μm). This parameter optimization achieves sufficient electrical insulation performance while avoiding excessive thickness that would complicate manufacturing processes and increase material costs, representing a balanced design solution.
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 solution achieves enhanced adhesiveness and durability of the insulating layer on the tubular member, preventing electric leakage and maintaining effective exhaust gas treatment performance even under extreme temperature fluctuations, thereby improving the overall purification efficiency.
Implementation Method 1
the insulating layer satisfies at least one of the following items (1) and (2) after the following peeling test: (1) an element derived from the insulating layer is present on the inner peripheral surface of the tubular main body; and (2) an element derived from the tubular main body is present in the insulating layer, where the peeling test involves repeating, until the insulating layer is peeled, an operation of placing the tubular member for an exhaust gas treatment device alternately in an environment of 900° C. and an environment of 150° C.
Data Source
AI summary
A tubular member for an exhaust gas treatment device according to at least one embodiment of the present invention includes: a tubular main body made of a metal; and an insulating layer formed at least on an inner peripheral surface of the tubular main body. The insulating layer contains glass, the glass contains barium, and the glass has a content of barium of 5 mol % or more.