Thermally Sprayed Piston Ring Coating for Wear Resistance
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Solution Overview
Problem
Current piston ring coatings using galvanic processes or thermal spraying with chromium-based materials do not effectively leverage the tribological benefits of chromium carbides, limiting wear resistance and efficiency in internal combustion engines.
Innovation Solution
A thermally sprayed coating system comprising 55-75% chromium, 3-10% silicon, 18-35% nickel, 0.1-2% molybdenum, 0.1-3% carbon, 0.5-2% boron, and 0-3% iron, with chromium carbides embedded in a Ni/Cr matrix, applied via high-speed flame or plasma spraying, to create a durable and wear-resistant piston ring coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If galvanic processes or conventional thermal spraying with chromium-based materials are used, then piston ring coatings can be produced, but wear resistance and tribological properties are limited
Solution Approach 1:
The patent applies composite materials by combining chromium carbide particles (Cr3C2) with a nickel-chromium matrix alloy powder. This composite structure provides both the wear resistance of hard chromium carbide particles and the ductility and adhesion of the Ni-Cr matrix, resolving the contradiction between achieving high wear resistance and maintaining effective coating production
Solution Approach 2:
The patent changes the material parameters by specifying a particular composition range: 55-75% Cr, 3-10% Si, 18-35% Ni, 0.1-2% Mo, 0.1-3% C, and 0.5-2% B. These parameter changes optimize the balance between hardness (from Cr3C2), ductility (from Ni-Cr matrix), and coating quality, enabling effective thermal spraying with superior tribological properties
2Reliability
If chromium carbides are incorporated into chrome layers using galvanic processes, then wear resistance is improved, but the coating time is significantly longer compared to thermal spraying
Solution Approach 1:
The patent replaces the galvanic process (electrochemical deposition) with thermal spraying (kinetic energy-based deposition). This substitution allows chromium carbide particles to be embedded in the coating matrix through high-velocity particle impact rather than electrochemical growth, dramatically reducing coating time from hours to minutes while maintaining wear resistance
Solution Approach 2:
The patent applies preliminary action by pre-mixing chromium carbide particles with the nickel-chromium alloy powder before spraying. This pre-prepared composite powder ensures proper particle distribution and embedding during the rapid thermal spraying process, achieving wear-resistant coatings in short coating times without requiring post-processing
3Productivity
If thermal spraying with chromium-based powder is used, then coating time is reduced, but the tribological properties and hardness are insufficient compared to galvanic chrome layers with carbides
Solution Approach 1:
The patent uses composite materials consisting of chromium carbide reinforcement particles distributed within a nickel-chromium matrix. The chromium carbide provides exceptional hardness and wear resistance, while the Ni-Cr matrix ensures ductility and adhesion. This composite structure achieves superior tribological properties through thermal spraying, matching or exceeding galvanic processes while maintaining fast coating speeds
Solution Approach 2:
The patent optimizes material parameters by controlling the composition within specific ranges: high chromium content (55-75%) for hardness, significant nickel content (18-35%) for ductility, and controlled carbon content (0.1-3%) to form chromium carbides. These parameter changes enable the thermal sprayed coating to achieve both fast application and excellent tribological performance
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 new coating system demonstrates improved hardness and wear resistance, with porosity under 5% and hardness of around 948 HV0.1, offering a viable alternative to traditional coatings with significantly reduced coating times and enhanced tribological properties.
Implementation Method 1
a coating obtainable by thermal spraying a powder comprising the element proportions 55-75 percent by weight chromium, Cr; 3-10 percent by weight silicon, Si; 18-35 percent by weight nickel, Ni
Implementation Method 2
the thermal spraying includes high-speed flame spraying or plasma spraying
Implementation Method 3
the thermal spraying includes high-speed flame spraying or plasma spraying
Implementation Method 4
The hard material particles for reducing wear in the thermally sprayed layer are chromium carbides (Cr3C2). The powder has Cr3C2 embedded in a Ni/Cr matrix.
Implementation Method 5
The powder has Cr3C2 embedded in a Ni/Cr matrix
Implementation Method 6
The use of Cr-based layer systems with chromium carbides as piston ring coating material, produced using plasma spraying or high velocity oxy fuel (HVOF), leads to the production of a new type of piston ring.
Data Source
Figure 1
AI summary
The invention relates to a sliding member for an internal combustion engine, comprising: a substrate; and a coating, obtainable by thermally spraying a powder, comprising the element proportions of 55 to 75 wt % of chromium, Cr; 3 to 10 wt % of silicon, Si; 18 to 35 wt % of nickel, Ni; 0.1 to 2 wt % of molybdenum, Mo; 0.1 to 3 wt % of carbon, C; 0.5 to 2 wt % of boron, B; and 0 to 3 wt % of iron, Fe.