Ceramic Heater Glass-Ceramic Coating for Thermal Shock Resistance
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Solution Overview
Problem
Ceramic heaters used for air conditioning in electric vehicles and heating/temperature keeping of batteries are prone to breaking due to thermal shock, especially when liquid droplets come into contact with the heated ceramic heater.
Innovation Solution
A ceramic heater design that includes a coat layer made of glass with adhered ceramic particles, particularly at corner portions and regions covering the heat generation resistor element, to mitigate thermal shock and prevent breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass (glaze) is applied to the surface of the ceramic heater to protect it, then the protection against thermal shock is improved, but at corner portions the glaze thickness decreases due to viscosity reduction at high firing temperatures
Solution Approach 1:
The patent applies a composite coating structure consisting of a glass-based coat layer combined with ceramic particles. The coat layer contains glass material with added ceramic particles, creating a composite material that maintains higher viscosity at firing temperatures compared to pure glass. This composite structure prevents excessive glaze thinning at corner portions while retaining the protective function against thermal shock.
Solution Approach 2:
The patent modifies the chemical composition parameters of the coat layer by incorporating ceramic particles into the glass matrix. This changes the viscosity-temperature relationship of the coating material, allowing it to maintain sufficient thickness at corner portions during high-temperature firing while still providing effective thermal shock protection.
2Reliability
If the glaze is applied a plurality of times to secure sufficient thickness at corner portions, then the protection is improved, but the man-hours and cost increase
Solution Approach 1:
By formulating a single-application composite coat layer containing ceramic particles, the patent eliminates the need for multiple glazing operations. The composite material's enhanced viscosity characteristics ensure adequate thickness retention at corner portions in one firing cycle, significantly reducing manufacturing time and cost while maintaining protective reliability.
Solution Approach 2:
The ceramic particles are pre-mixed into the glaze material before application, preparing the coating to resist thinning during firing. This preliminary incorporation of viscosity-enhancing particles ensures that the single application will maintain sufficient thickness without requiring subsequent re-coating operations.
3Reliability
If a liquid droplet comes into contact with the ceramic heater in a heating state, then thermal shock occurs, but the ceramic heater is vulnerable to breaking
Solution Approach 1:
The composite coat layer with ceramic particles provides enhanced thermal shock resistance. The ceramic particles within the glass matrix create a more robust coating structure that can withstand sudden temperature changes from liquid droplet contact, preventing crack propagation and maintaining structural integrity of the ceramic heater.
Solution Approach 2:
The coat layer acts as a protective cushion applied beforehand to the ceramic heater surface. This pre-applied protective layer absorbs and distributes the thermal stress from liquid droplet contact, preventing direct thermal shock to the underlying ceramic body and avoiding structural failure.
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 proposed design effectively reduces thermal shock at vulnerable areas, thereby preventing the ceramic heater from breaking due to thermal stress, ensuring reliable operation and longevity.
Implementation Method 1
a heat generation resistor element having a predetermined heater pattern is formed in the ceramic layer. When electricity is supplied to the heat generation resistor element, the ceramic heater generates heat.
Implementation Method 2
since the ceramic heater is vulnerable to thermal shock, when the ceramic heater heated to a high temperature is rapidly cooled, there arises a possibility that a crack or the like is generated and the heater is broken.
Data Source
AI summary
A ceramic heater 100 including: a ceramic body 10 including a heat generation resistor element 13; and a coat layer 20 formed mainly of glass and configured to cover at least corner portions 11E,12E of the ceramic body and a region including the heat generation resistor element, wherein ceramic particles 21 are adhered to at least a portion of a region of a surface of the coat layer where the coat layer covers the ceramic body.