Dry Antifriction Coating for Stable Fastener Friction and Corrosion
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Solution Overview
Problem
Current industrial processes for lubricating metal fasteners, such as phosphating followed by oil or wax application, face issues like inconsistent corrosion protection, coefficient of friction variability, soiling, dust pickup, and hydrogen embrittlement, particularly in high-strength steel fasteners.
Innovation Solution
A dry anti-friction coating comprising a polymeric resin binder, a polyorganosiloxane resin, a thickener, solid lubricants, and a solvent, applied as a thin film to provide permanent lubrication without the need for additional wet lubricants, using a combination of phenolic, epoxy, and silicone resins with polyamide thickeners and specific solid lubricants like PTFE, and applied via conventional techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phosphating pre-treatment followed by oil/wax layer application is used, then lubrication is provided, but corrosion protection becomes inconsistent and hydrogen embrittlement occurs
Solution Approach 1:
The patent removes the phosphating pre-treatment step from the conventional process sequence. By applying the dry lubricant coating directly to the metal substrate without phosphating, the invention eliminates the source of hydrogen embrittlement while maintaining consistent corrosion protection through the resin binder system.
Solution Approach 2:
The invention uses a composite coating formulation comprising resin binder, solid lubricants, and thickener. This composite material provides both corrosion protection and lubrication in a single layer, replacing the multi-layer phosphating-oil/wax system and eliminating the harmful effects of phosphating while maintaining reliability.
2Reliability
If oil/wax layer is applied after phosphating, then lubrication is achieved, but the film spreads away causing coefficient of friction variability
Solution Approach 1:
The patent changes the physical state of the lubricant from liquid (oil/wax) to solid particles embedded in a resin matrix. This parameter change allows the lubricant to remain fixed in position on the substrate surface, preventing film spreading and ensuring consistent coefficient of friction values.
Solution Approach 2:
The dry lubricant coating is a composite material where solid lubricant particles are dispersed and fixed within a resin binder system. This composite structure provides both position stability and consistent lubrication performance, eliminating the film spreading issue inherent in liquid oil/wax applications.
3Duration of action of stationary object
If conventional dry lubricant coating is applied, then permanent lubrication is provided, but the coating thickness and composition must be precisely controlled
Solution Approach 1:
The patent incorporates a thickener component in the coating formulation that allows the application of a slightly thicker coating than the minimum required. The excess material ensures complete coverage and proper film formation without requiring extremely precise thickness control, while still achieving the desired permanent lubrication effect.
Solution Approach 2:
The resin binder acts as an intermediary that holds solid lubricant particles in a distributed arrangement within the coating matrix. This intermediary structure allows the coating to maintain proper composition and thickness distribution, ensuring both permanent lubrication and reduced sensitivity to thickness variations.
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 dry anti-friction coating offers consistent corrosion protection, controlled coefficient of friction, prevents soiling, reduces dust issues, and avoids hydrogen embrittlement, providing a maintenance-free lubrication system that meets industry requirements for engine fasteners.
Implementation Method 1
The resin binder (i) acts to provide adhesion and anchorage of the anti-friction coating to the substrate
Implementation Method 2
a solvent (iv) which acts to dissolve the resin (i) and enable application of an uncured anti-friction coating on the substrate
Implementation Method 3
followed by heating to evaporate the solvent and cure the coating
Data Source
AI summary
An antifriction coating composition which comprises: a resin binder, a polyamide thickener, solvent and a solid lubricant wherein the resin binder comprises a mixture of phenolic resin, epoxy resin and optionally a silicone resin.