Iron-Sprayed Cylinder Bore Coating for Scuffing Resistance
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Solution Overview
Problem
Conventional iron-based sprayed coatings for internal combustion engine cylinder blocks face issues with scuffing and peeling due to high combustion pressures and loads, leading to potential engine breakage.
Innovation Solution
An iron-based sprayed coating with controlled pit amount (0.01% to 0.21%) and surface roughness (0.01 µm to 0.15 µm) is applied to the cylinder block's inner surface, combined with a piston ring coated with chromium, chromium nitride, or diamond-like carbon, to enhance scuffing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional iron-based sprayed coating is applied to improve abrasion resistance, then abrasion resistance is improved, but scuffing resistance deteriorates under high combustion pressure
Solution Approach 1:
The invention changes the surface parameters of the sprayed coating by precisely controlling the pit amount (0.01% to 0.21%) and surface roughness (Ra: 0.01 μm to 0.15 μm). This parameter optimization allows the coating to maintain adequate abrasion resistance while achieving excellent scuffing resistance under high combustion pressure conditions.
Solution Approach 2:
The invention utilizes a controlled porous structure with specific pit amount (0.01% to 0.21%) on the coating surface. These pits act as oil reservoirs that retain lubricating oil under high pressure, preventing direct metal-to-metal contact and scuffing, while the controlled porosity maintains the coating's structural integrity for abrasion resistance.
2Reliability
If nickel plating is applied to aluminum alloy cylinder block to improve scuffing resistance, then scuffing resistance is improved, but abrasion resistance deteriorates
Solution Approach 1:
The invention uses an iron-based sprayed coating composed of multiple phases including austenite, martensite, and carbides, creating a composite material structure. This composite structure provides both the hardness needed for abrasion resistance and the surface characteristics (controlled pits and roughness) for scuffing resistance, overcoming the limitations of single-material nickel plating.
3Strength
If plasma flame spraying is used to form sprayed coating, then coating adhesion is improved, but surface roughness increases leading to scuffing
Solution Approach 1:
The invention optimizes the spraying parameters and post-processing conditions to achieve a precise surface roughness (Ra: 0.01 μm to 0.15 μm) and controlled pit formation. This level of surface control maintains strong coating adhesion from the plasma spraying process while preventing excessive roughness that would cause scuffing under high load.
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 coating achieves excellent scuffing resistance, low friction, and improved oil retention, reducing the risk of engine failure and enhancing the durability of the cylinder block and piston ring under high load conditions.
Implementation Method 1
spraying on spray powder by plasma flame to a cylinder bore inner surface to form a sprayed coating
Implementation Method 2
a piston ring coated with chromium, chromium nitride, or diamond-like carbon
Data Source
Figure 1~2
Figure 3~4
AI summary
An iron-based sprayed coating for coating a bore inner surface of a cylinder block for an internal combustion engine. A coating surface contains pits, its pit amount is within a range of 0.01% to 2.1%, and an average roughness Ra of this coating surface is within a range of 0.01 µm to 0.15 µm. The cylinder block for an internal combustion engine includes a bore having this iron-based sprayed coating on its inner surface, and a cylinder block body having the bore. A sliding mechanism for an internal combustion engine includes this cylinder block for an internal combustion engine and a piston slidable with the bore of this cylinder block. The piston has a piston ring, and the piston ring has a chromium coating, a chromium nitride coating, or a diamond-like carbon coating at a sliding part with the bore.