Method of manufacturing dishwasher
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Solution Overview
Problem
The existing hydrophilic coatings on dishwasher inner walls suffer from insufficient durability against alkaline and acidic detergents, leading to adhesion issues with oil stains and calcium deposits, which complicates cleaning and maintenance.
Innovation Solution
A method involving a two-layer coating process on stainless steel surfaces, where a first layer of zirconium oxide and silicon oxide is formed at 200°C or higher, followed by a second layer containing an oxoacid at a lower temperature, resulting in a thin-film layer with enhanced hydrophilicity and durability against both alkaline and acidic detergents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a hydrophilic coating containing silicic acid component is formed on the stainless steel plate, then adhesion of oil stains is prevented and drying time is shortened, but durability against alkaline detergent deteriorates
Solution Approach 1:
The patent uses a composite coating containing both silicic acid component (for hydrophilicity) and zirconium oxide component (for alkali resistance). This composite structure allows the coating to simultaneously achieve short drying time and high durability against alkaline detergent, resolving the contradiction between ease of operation and reliability.
2Reliability
If zirconium oxide and phosphoric acid component are used to improve alkali resistance, then durability against alkaline detergent is improved, but acid resistance deteriorates
Solution Approach 1:
The patent replaces phosphoric acid component with silicon oxide component in the composite coating. Silicon oxide provides both hydrophilicity and maintains acid resistance while allowing high zirconium oxide content for alkali resistance. This composite formulation resolves the contradiction between alkali resistance and acid resistance.
3Ease of operation
If hydrophilic coating is applied to prevent oil stain adhesion, then cleaning ease is improved, but calcium removal capability deteriorates
Solution Approach 1:
The composite coating with zirconium oxide and silicon oxide maintains surface hydrophilicity for oil stain prevention while the specific composition and structure allow calcium to not adhere strongly, enabling easy removal with acidic detergent. The coating composition resolves the contradiction between cleaning ease and calcium removal capability.
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 creates a hydrophilic surface that prevents oil stains and facilitates quick drying, while maintaining excellent durability against detergents, ensuring efficient cleaning and energy savings.
Implementation Method 1
forming a first layer containing zirconium oxide and silicon oxide on the surface of the inner wall at a heat treatment temperature of 200° C. or higher
Implementation Method 2
forming a second layer containing an oxoacid on the surface of the first layer at a heat treatment temperature lower than the heat treatment temperature of the first layer
Implementation Method 3
water easily infiltrates into the interface between the oil stains and the hydrophilic coating
Implementation Method 4
having a contact angle of water of 20 degrees or less on the surface
Data Source
AI summary
Disclosed is a method of manufacturing a dishwasher including: forming a first layer containing zirconium oxide and silicon oxide on a surface of the inner wall at a heat treatment of 200° C. or higher; forming a second layer containing an oxoacid on a surface of the first layer at a heat treatment temperature lower than the heat treatment temperature of the first layer; and obtaining a thin-film layer containing zirconium oxide and silicon oxide on the surface of the inner wall and having a contact angle of water of 20° or less on the surface, after removing the second layer by using a washing method, in which the first layer contains the zirconium oxide in an amount of 80 mass % or more in terms of oxide and the silicon oxide in an amount of 1-20 mass % in terms of oxide.