Hose Corrosion Resistance via Sulfate Ion Control
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Solution Overview
Problem
Hydraulic hoses face corrosion issues when used with water-based hydraulic fluids due to moisture penetration, which affects the reinforcing material layer, and existing solutions do not adequately address the need for maintaining high oil resistance while suppressing corrosion.
Innovation Solution
The hose design incorporates a specific concentration of sulfate ions in the inner tube rubber layer and woven material underlayer, ensuring the concentration is lower than a predetermined value, thereby preventing corrosion of the reinforcing material layer while maintaining high oil resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If water-based hydraulic fluid is used, then the hose can be used in applications requiring water-based fluid, but moisture penetration causes corrosion of the reinforcing material layer
Solution Approach 1:
The patent introduces an intermediate rubber layer between the inner tube rubber layer and the reinforcing material layer. This intermediate layer acts as a mediator that prevents moisture from the water-based hydraulic fluid from reaching and corroding the reinforcing material layer, while still allowing the hose to function with water-based fluids.
Solution Approach 2:
The patent uses a sacrificial protective layer (the intermediate rubber layer or modified inner tube rubber layer) that is designed to be consumed or degraded before the reinforcing material layer is affected. This disposable protective barrier prevents corrosion of the critical reinforcing material.
2Reliability
If acrylonitrile butadiene rubber (NBR) is used in the inner tube rubber layer, then oil resistance is improved, but sulfate ion concentration increases which causes corrosion when water-based fluid is used
Solution Approach 1:
The patent applies different material compositions to different layers: the inner tube rubber layer uses NBR for oil resistance when in contact with hydraulic oil, while the intermediate rubber layer uses materials with low sulfate ion content to prevent corrosion when in contact with water-based fluids and reinforcing materials. Each layer has locally optimized properties for its specific function.
Solution Approach 2:
The patent creates a composite hose structure combining different rubber materials with complementary properties. The inner tube uses NBR for oil resistance, while the intermediate layer uses rubber compounds with suppressed sulfate ion content to provide corrosion protection, creating a multi-material composite structure that achieves both oil resistance and corrosion resistance.
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
This approach effectively suppresses corrosion of the reinforcing material layer and maintains satisfactory oil resistance, as demonstrated by the hydraulic pressure impulse test, achieving a high number of impulses without failure.
Implementation Method 1
there exists a possibility that moisture contained in the water-based hydraulic fluid permeates into the hose, thereby corroding a reinforcing material of the reinforcing material layer
Data Source
Figure 1~2
AI summary
A hose includes an inner tube rubber layer, a woven material underlayer having a woven base material made of polyamide (PA) or polyethylene terephthalate (PET), and a reinforcing material layer, which are sequentially laminated on the inner rube rubber layer in this order. Following relationship formula (1) is to be satisfied, A⋅t+B⋅C<D wherein "A" represents SO42- concentration in the inner tube rubber layer (unit: mol/mm3), "t" represents thickness of the inner tube rubber layer (unit: mm), "B" represents SO42- concentration per 1 g of the woven base material (unit: mol/g), "C" represents mass of the woven base material per unit area of the woven material underlayer (unit: g/mm2), and "D" represents a constant of 2.5 × 10-9 (unit: mol/mm2). 100 pbm of a rubber component contains at least 60 pbm of acrylonitrile butadiene rubber (NBR) and t ≥ 0.5 mm.