Sn Alloy Sliding Member With Laser-Clad Bonding and Fatigue Resistance
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Solution Overview
Problem
Existing sliding members face challenges in achieving high fatigue resistance and adhesive strength between Sn alloy and Fe-based back metal layers without using environmentally harmful elements like Cd or Be, which are required in previous solutions to prevent segregation and improve intermetallic compound fineness.
Innovation Solution
A sliding member with a Sn alloy layer containing a Sn-based intermetallic compound dispersed in a Sn alloy matrix, where the contact state between the Sn alloy matrix and the Fe-based back metal layer ensures a minimum 30% interface contact length and 40-70% intermetallic compound area, and the manufacturing method involves laser cladding to control intermetallic compound generation, excluding harmful substances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If excessive Cu or Sb is added to the Sn alloy layer, then the intermetallic compounds become finer and fatigue resistance improves, but segregation occurs at the interface and adhesive strength decreases
Solution Approach 1:
The patent changes the compositional parameters by limiting Cu to 1-3 mass% and Sb to 1-5 mass%, and introduces a new parameter (Bi content of 1-10 mass%) to achieve the desired intermetallic compound fineness and distribution without excessive segregation, thereby maintaining both fatigue resistance and adhesive strength
Solution Approach 2:
The patent introduces Bi (thallium) as an intermediary element that mediates between the Cu/Sb additions and the Sn matrix, enabling finer intermetallic compound formation while preventing excessive segregation at the interface, thus resolving the contradiction between fatigue resistance and adhesive strength
2Reliability
If Cd or Be is added to reduce segregation and make intermetallic compounds finer, then adhesive strength and fatigue resistance improve, but environmental harm increases
Solution Approach 1:
The patent extracts and removes the harmful elements Cd and Be from the alloy composition entirely, replacing their function with environmentally friendly alternatives (Bi, Cu, Sb) that achieve the same technical effects of reducing segregation and refining intermetallic compounds without environmental harm
Solution Approach 2:
The patent uses common, environmentally friendly elements (Bi, Cu, Sb) that are less hazardous and more sustainable compared to rare or toxic elements like Cd and Be, achieving similar technical effects with more environmentally acceptable materials
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 approach enhances both adhesive strength and fatigue resistance without using environmentally harmful substances, ensuring uniform dispersion of intermetallic compounds for improved hardness and reduced segregation, thus improving the sliding member's performance.
Implementation Method 1
In the irradiating step, laser light is irradiated to one end surface of the back metal layer. In the alloy layer forming step, the alloy material loaded in the loading step is molten on a surface of the back metal layer by using the irradiated laser light
Data Source
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AI summary
A sliding member (10) of the present embodiment includes a Sn alloy layer (11) and an Fe-based back metal layer (12). In any observation cross-section (20) at an interface (21) between the Sn alloy layer (11) and the back metal layer (12), an entire length in which a Sn alloy matrix (13) included in the Sn alloy layer (11) and the back metal layer (12) are in contact with each other is 30% or more of an entire length of the interface (21). In the observation cross-section (20), a sum of areas of the intermetallic compound (14) is 40% or more and 70% or less of a total area of the Sn alloy layer (11). When a plurality of viewing fields having the same area are freely extracted from a cross section of the Sn alloy layer (11), a difference D=A-B between an area percentage A% in a first viewing field having the maximum area percentage of the intermetallic compound (14) among the plurality of viewing fields and an area percentage B% in a second viewing field having the minimum area percentage of the intermetallic compound (14) among the plurality of viewing fields is equal to or smaller than 20%.