Honeycomb Structure Solder Diffusion Control
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Solution Overview
Problem
The existing methods for manufacturing abradable blocks for turbine blades result in solder spreading and increasing the hardness of the blade tips, leading to premature wear and reduced seal effectiveness due to capillary diffusion of solder to the second ends of the metal sheets.
Innovation Solution
A method involving metal sheets with corrugations forming semi-hexagonal patterns, where openings or anti-wetting products are applied at the crown zones to prevent solder diffusion to the second ends, ensuring controlled hardness and reducing blade wear by blocking solder propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If solder is applied to join metal sheets in the honeycomb structure, then the sheets are securely connected to the support plate, but solder spreads by capillarity to the second ends of the sheets increasing hardness and damaging blade tips
Solution Approach 1:
A flux barrier layer is introduced as an intermediary substance between the solder and the metal sheets. This barrier layer prevents the solder from spreading by capillarity along the sheet surfaces while still allowing the solder to effectively join the sheets to the support plate. The flux barrier thus mediates between the need for strong joints and the need to prevent harmful solder propagation to the blade tips.
Solution Approach 2:
The patent applies different properties to different regions: the solder is allowed to flow freely at the first ends where it joins the support plate, but the second ends are protected by the flux barrier layer that locally prevents solder spreading. This local differentiation of solder flow properties ensures strong connections where needed while preventing damage where not needed.
2Strength
If solder is applied to secure sheets to the support plate, then mechanical strength is improved, but the hardness of the second ends increases causing premature wear
Solution Approach 1:
The flux barrier layer acts as a mediator that allows the soldering process to proceed effectively for joining purposes while simultaneously preventing the harmful side effect of solder propagation. This intermediary substance enables the system to achieve strong mechanical joints without the trade-off of increased hardness and reduced blade life.
Solution Approach 2:
The patent converts the potentially harmful capillary action of solder into a beneficial controlled process. By using the flux barrier layer, the solder's natural tendency to spread is redirected and contained, allowing the soldering process to provide strong joints without the harmful propagation that would otherwise occur.
3Strength
If a eutectic forms from sheet material and brazing element, then bonding is strengthened, but hardness of second ends increases further
Solution Approach 1:
The flux barrier layer creates a local quality difference in the system: areas with the barrier layer (near the second ends) have restricted solder flow and lower hardness, while areas without the barrier layer (at the first ends and support plate interface) have full solder penetration and high bonding strength. This local differentiation resolves the contradiction between bonding strength and excessive hardness.
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 prevents solder from reaching the blade tips, maintaining blade longevity and reducing maintenance needs by controlling the hardness and ensuring a consistent seal against hot flows.
Implementation Method 1
arranging a brazing element between the support plate and said first ends of the sheets and heating the assembly in an oven
Implementation Method 2
solder can spread by capillarity from the first ends of the sheets to the second ends opposite said first ends
Data Source
Figure 1~4
Figure 5~6
AI summary
The invention concerns a method for producing a honeycomb structure, comprising the following steps: a) providing a plurality of metal sheets (126) each having, in a first direction, corrugations formed from a succession of crown areas (28) arranged in alternation with connecting areas (30); b) juxtaposing the sheets (126) in such a way as to form cells; c) bringing a first end (26a) of each sheet (126) into contact with a support plate; d) arranging a solder element between the support plate (34) and the first ends (26a) of the sheets (126) and heating the assembly in a furnace. According to the invention, prior to step d), the method consists in adding a means for blocking the diffusion of solder from said first ends (26a) of the sheets (126) to the free second ends (26b) of the sheets (126).