Slide Member Oxide Coating for Refrigerant Compressor Abrasion
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Solution Overview
Problem
Refrigerant compressors face challenges in effectively suppressing metal surface contact and improving lubricating oil retention, especially with lower viscosity oils, leading to increased load on sliding surfaces, degradation of phosphate coating films, and potential abnormal abrasion due to refrigerant gas bubbles.
Innovation Solution
A slide member with an iron-based material and a three-layer oxide coating film structure (Fe2O3, Fe3O4, FeO) is used, along with dense oxide coating films having minute concave/convex portions, to enhance abrasion resistance and lubricating oil retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a phosphate coating film is used to reduce metal surface contact, then sliding smoothness is improved, but the coating film becomes abrasive and wears out
Solution Approach 1:
The invention uses a composite coating structure consisting of a soft phosphate coating layer (0.5-5 μm thick) combined with an oxide coating layer (5-20 μm thick) on the slide member surface. This composite structure allows the soft phosphate layer to reduce friction and metal contact while the harder oxide layer prevents abrasion and wear, resolving the contradiction between sliding smoothness and coating durability
Solution Approach 2:
The invention applies different coating properties to different depths of the surface: the phosphate coating provides low friction at the outermost surface for smooth sliding, while the oxide coating provides high hardness and wear resistance at the underlying layer, creating local quality differentiation that addresses both contradictory requirements
2Productivity
If lower viscosity lubricating oil is used to improve compressor efficiency, then energy efficiency is improved, but lubricating oil retention capability deteriorates
Solution Approach 1:
The invention utilizes the porous structure of the phosphate coating film to retain lubricating oil. The phosphate coating's porosity creates capillary action that holds the lubricating oil in place, ensuring adequate lubrication even when low viscosity oils are used for improved compressor efficiency
Solution Approach 2:
The invention changes the surface parameters by applying coatings with specific thickness ranges (phosphate: 0.5-5 μm, oxide: 5-20 μm) and controlled surface roughness (Ra 0.03-0.3 μm), which optimizes the retention of low viscosity lubricating oil while maintaining compressor efficiency
3Force
If metal surfaces are allowed to contact to improve load bearing, then structural simplicity is improved, but abrasion and wear increase
Solution Approach 1:
The invention introduces an oxide coating layer as an intermediary between the metal substrate and the phosphate coating surface. This oxide layer acts as a mediator that provides high load bearing capacity through its hardness and structural integrity while preventing direct metal-to-metal contact and the associated abrasion and wear
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 solution improves abrasion resistance, reliability, and efficiency of the refrigerant compressor by reducing sliding losses and maintaining effective lubrication even with low viscosity oils, while preventing metal surface contact and refrigerant gas-induced abrasion.
Implementation Method 1
a dense oxide coating film having minute concave/convex portions with a height difference which falls within a range of 0.01 μm to 0.1 μm is formed on the surface of the base material
Implementation Method 2
the phosphate coating film 20 has the porous crystalline body, the retention capability of lubricating oil between the sliding surfaces can be improved. As a result, smooth sliding of the slide unit can be realized
Data Source
AI summary
A slide member of the present invention is used in a slide unit which is included in a refrigerant compressor for compressing a refrigerant and provided inside a sealed container which reserves lubricating oil therein. The slide member is provided with an oxide coating film on a surface of a base material. The oxide coating film is configured such that (1) when the base material comprises an iron based material, the oxide coating film has a three-layer structure including a first layer comprising Fe2O3, a second layer comprising Fe3O4, and a third layer comprising FeO in this order from an outermost surface, (2) the oxide coating film has a dense structure having minute concave/convex portions with a height difference which falls within a range of 0.01 μm to 0.1 μm, or (3) when the base material comprises the iron based material, the oxide coating film has a three-layer structure in which the three layers comprise the iron oxides and are different in hardness.