Compressor Sliding Materials for HF Corrosion and Friction Control
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Solution Overview
Problem
Compressors in refrigeration systems using chlorine atom-free low-global warming potential hydrofluoroolefins as refrigerants face corrosion issues due to the generation of hydrogen fluoride when reacting with water and oxygen, leading to reliability concerns, particularly in severe sliding regions like the vane and piston interfaces.
Innovation Solution
The use of nitrided steel for sliding components with CrN or DLC coatings by PVD treatment, combined with Ni—Cr—Mo cast iron for pistons, and a refrigeration oil miscible with the refrigerant, helps suppress temperature rise and corrosion from hydrogen fluoride generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional sliding materials are used in compressors with hydrofluoroolefin refrigerants, then the compressor can operate with low global warming potential refrigerant, but hydrogen fluoride corrosion accelerates and reliability deteriorates
Solution Approach 1:
The patent employs composite material structures: nitrided steel for the vane with CrN or DLC coating, and Ni-Cr-Mo cast iron for the piston. These composite materials combine different properties (hardness, corrosion resistance, lubricity) to simultaneously withstand the corrosive HF environment and severe sliding conditions while maintaining compatibility with HFO refrigerants.
Solution Approach 2:
The patent changes the material parameters through nitriding treatment (altering surface composition and structure of steel) and selecting specific alloy compositions (Ni-Cr-Mo cast iron). These parameter changes enhance corrosion resistance and reduce friction, preventing HF generation and maintaining reliability in HFO refrigerant systems.
2Strength
If nitridation treatment and PVD coating are applied to sliding materials, then abrasion resistance improves, but manufacturing complexity increases
Solution Approach 1:
The nitridation treatment and PVD coating are applied as preliminary actions during manufacturing, before the compressor enters service. This approach establishes the protective surface layers in advance, ensuring abrasion resistance without requiring complex real-time controls during operation.
Solution Approach 2:
The nitridation treatment and PVD coating are applied locally to the sliding surfaces (vane and piston contact areas) rather than treating entire components. This localized approach provides enhanced abrasion resistance where needed while minimizing manufacturing complexity and cost.
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 configuration enhances the reliability and abrasion resistance of compressor components by controlling hydrogen fluoride corrosion and maintaining performance under severe sliding conditions.
Implementation Method 1
a CrN or DLC film is formed on the surface thereof by PVD treatment
Implementation Method 2
a steel is used as the base material such as vane for one sliding material in the compressing mechanism unit and nitrided
Data Source
AI summary
A compressor, characterized in that a steel is used as the base material for the other sliding material vane 10 and nitrided, a CrN or DLC film is formed on the surface by PVD treatment, and a Ni—Cr—Mo cast iron is used for the other corresponding sliding material piston 9. It is possible in such a configuration to suppress the temperature rise by sliding friction of the sliding materials, such as the vane tip region 10a and the peripheral region of piston 9 that are vigorously slid, relax decomposition of the refrigerant, and suppress corrosion by hydrogen fluoride generated in reaction with water and oxygen, and thus to provide a compressor higher in reliability.