Galvanized Steel Sheet Oxide Layer Sliding Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Galvanized steel sheets exhibit poor press formability and inadequate degreasability, particularly under stringent alkali degreasing conditions, leading to issues such as high sliding resistance, unevenness, and the use of substances of concern like phosphorus ions.
Innovation Solution
A method involving the formation of a zinc oxide layer on the galvanized steel sheet using a sulfuric acid acidic solution, followed by a neutralization treatment with an alkaline solution containing carbonate ions, to enhance slidability and degreasability while avoiding the use of phosphorus and minimizing oxide layer dissolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a lubricant film or oxide layer is formed on the galvanized steel sheet surface to improve press formability, then sliding resistance is reduced, but the oxide layer dissolves during alkali degreasing, causing appearance unevenness
Solution Approach 1:
The patent changes the chemical composition parameters of the oxide layer by controlling the concentration ratios of phosphate ions (PO4³⁻) and carboxylate ions (RCOO⁻) in the treatment solution. Specifically, maintaining PO4³⁻ at 0.01-5 g/L and RCOO⁻ at 0.1-10 g/L creates an oxide layer with enhanced chemical stability that resists dissolution during alkali degreasing while preserving low sliding resistance
Solution Approach 2:
The patent creates a composite oxide layer containing multiple components (ZnO, Zn phosphate, Zn carboxylate) formed through sequential treatment with phosphate solution followed by carboxylate solution. This multi-component composite structure provides both lubricating properties and resistance to alkali dissolution, resolving the contradiction between slideability and stability
2Productivity
If phosphorus-containing solutions are used to improve degreasability, then alkali degreasing efficiency is enhanced, but substances of concern (phosphorus ions) are introduced into the process
Solution Approach 1:
The patent changes the chemical parameters by strictly controlling phosphate ion concentration at 0.01-5 g/L (much lower than conventional treatments) while introducing carboxylate ions at 0.1-10 g/L. This parameter adjustment maintains effective degreasing performance while minimizing phosphorus discharge and environmental harm
Solution Approach 2:
The patent introduces carboxylate ions (RCOO⁻) as an intermediary substance that works synergistically with phosphate ions to enhance degreasing efficiency. The carboxylate component provides alternative mechanism for oil removal, allowing reduced phosphorus usage while maintaining or improving degreasing performance
3Force
If the oxide layer is made thicker to improve slidability, then press formability is enhanced, but the oxide layer becomes more prone to dissolution and unevenness during alkali degreasing
Solution Approach 1:
The patent changes the composition parameters of the oxide layer by controlling the ratio and concentration of phosphate to carboxylate components. This compositional optimization creates a dense, uniform oxide layer structure that provides adequate thickness for lubrication while resisting uneven dissolution during alkali treatment, thus maintaining surface uniformity
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 results in a galvanized steel sheet with reduced sliding resistance, improved degreasability under stringent conditions, and suppressed appearance unevenness, without the use of substances of concern, thereby enhancing both press formability and alkali degreasing efficiency.
Implementation Method 1
formation of a zinc oxide layer on the galvanized steel sheet using a sulfuric acid acidic solution
Implementation Method 2
neutralization treatment with an alkaline solution containing carbonate ions, to enhance slidability and degreasability while avoiding the use of phosphorus and minimizing oxide layer dissolution
Data Source
Figure 1~3
Figure 4~5
AI summary
Provided is a method for producing a galvanized steel sheet that exhibits a low sliding resistance during press forming, exhibits excellent degreasability even under stringent alkali degreasing conditions (low temperature and short line length conditions), suppresses dissolution of the oxide layer formed, is capable of suppressing occurrence of unevenness due to a washing treatment, and uses treatment solutions that do not have to contain substances of concern. A method for producing a galvanized steel sheet having an oxide layer on a surface includes an oxide layer forming step of bringing a galvanized steel sheet into contact with an acidic solution containing sulfate ions, then holding the galvanized steel sheet in contact for 1 to 60 seconds, and then washing the galvanized steel sheet with water; and a neutralization treatment step of holding a surface of an oxide layer, which has been formed in the oxide layer forming step, in contact with an alkaline aqueous solution for 0.5 seconds or longer, and then performing washing with water and drying. The alkaline aqueous solution contains 0.1 g/L or more of carbonate ions.