Polysiloxane hydraulic fluids
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Solution Overview
Problem
Current hydraulic fluids used in aircraft, particularly those based on phosphate esters, exhibit undesirable properties such as paint stripping, metal corrosion, plastic dissolution, and increased acidity, along with the use of user-unfriendly additives and fluorinated surfactants like perfluoroalkylsulfonic acid salts, necessitating the development of more benign and user-friendly alternatives.
Innovation Solution
Hydraulic fluid compositions comprising polysiloxane and diphosphonate compounds, with specific molecular structures and ratios, providing suitable viscosity, fire retardancy, lubricity, and reduced corrosiveness, while omitting harmful additives like fluorinated surfactants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If phosphate ester-based hydraulic fluids are used, then fire retardant properties are provided, but paint stripping, metal corrosion, plastic dissolution, and increased acidity occur
Solution Approach 1:
The patent changes the chemical composition parameters by replacing phosphate esters with polysiloxanes and diphosphonates, maintaining fire retardancy while eliminating harmful effects. Specifically, it uses polysiloxane base stock with diphosphonate additives to achieve the desired balance of safety and benign properties
Solution Approach 2:
The patent creates a composite hydraulic fluid system combining polysiloxane base stock with diphosphonate additives. This composite approach allows the base fluid to provide fire retardancy while the additive package mitigates corrosiveness and maintains material compatibility
2Object-generated harmful factors
If phosphate ester-based hydraulic fluids with additives are used, then some undesirable properties are mitigated, but the additives are user unfriendly or involve future supply restrictions
Solution Approach 1:
The patent extracts and eliminates problematic additives from the hydraulic fluid formulation. By using polysiloxane base stock, it inherently reduces the need for certain conventional additives, particularly fluorinated surfactants, thereby improving user friendliness and avoiding supply restrictions
3Object-affected harmful factors
If fluorinated surfactants are used as anti-erosion agents, then erosion protection is provided, but the fluids become less user friendly
Solution Approach 1:
The patent removes fluorinated surfactants from the formulation and replaces them with alternative anti-erosion mechanisms. The polysiloxane base stock combined with diphosphonate additives provides erosion protection through different chemical mechanisms that are more environmentally friendly and user acceptable
Data Source
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AI summary
The present disclosure relates to polysiloxanes, processes for preparing polysiloxanes, and hydraulic fluids comprising polysiloxanes. This disclosure also relates to hydraulic fluids comprising one or more polysiloxane compounds and diphosphonate compounds, and to the use of diphosphonate compounds in hydraulic fluids or as additives or components in various compositions, for example to provide fire retardant properties to a fluid or composition. This disclosure also relates to use of the compositions as hydraulic fluids, which may be used in various machines, vehicles and craft, including aircraft.