Pressureless Sintering of Hollow Metal Spheres for Acoustic Hot Parts
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Solution Overview
Problem
Existing methods for acoustic treatment of aircraft engine 'hot' parts are lacking, and sintering techniques using nickel-based and ceramic spheres are limited by temperature capabilities and mechanical strength, failing to provide the necessary acoustic absorption and mechanical resilience for aircraft engine environments.
Innovation Solution
A process involving sintering of metal bodies in a high vacuum with an organic substance at a temperature above the eutectic melting point of carbon and metal constituents, using a blend of metal powder and organic binder to create dense, multifunctional, and acoustically absorbent metal structures without external pressure, allowing for the production of hollow metal bodies with enhanced mechanical strength and resistance to oxidation and corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional sintering methods are used to densify metal powder, then external pressure must be applied at high temperature, but this limits the variety of material combinations and temperature capabilities
Solution Approach 1:
The invention changes the temperature parameter to exceed the melting point of the metal powder (up to 1500°C or higher), enabling sintering without external pressure. This temperature parameter change allows the liquid metal to naturally densify the powder compact, eliminating the need for complex pressure application equipment while enabling versatile material combinations including refractory metals and ceramics.
Solution Approach 2:
The invention replaces the mechanical pressure system with a thermal field system. Instead of applying external mechanical pressure to densify the powder, the process uses high temperature to melt the metal binder, which then flows and densifies the compact under its own weight and capillary forces, substituting mechanical densification with thermal-driven liquid-phase sintering.
2Strength
If high temperature sintering is used to improve material performance, then mechanical strength increases, but oxidation and corrosion resistance deteriorates in conventional atmospheres
Solution Approach 1:
The invention uses a controlled atmosphere (inert gas or vacuum) during the high-temperature sintering process to prevent oxidation and corrosion of the metal powder and finished product. This inert environment allows the material to be heated above its melting point without deteriorating from oxidative damage, thereby achieving high mechanical strength while maintaining corrosion and oxidation resistance.
3Manufacturing precision
If external pressure is applied during sintering to achieve densification, then manufacturing precision improves, but the process complexity and equipment requirements increase
Solution Approach 1:
The invention replaces complex mechanical pressure application systems with a simpler thermal processing system. By heating the powder compact above the melting point of the metal binder, the liquid metal naturally flows to densify the structure, achieving high manufacturing precision without requiring complex isostatic pressing or hot pressing equipment.
4Object-affected harmful factors
If conventional cellular materials are used for noise absorption, then acoustic treatment is achieved, but temperature capability and mechanical strength are limited
Solution Approach 1:
The invention uses composite materials consisting of metal powder compacts with controlled porosity, where the metal matrix provides high temperature capability and mechanical strength while the porous structure delivers noise absorption. The composite nature allows simultaneous achievement of acoustic treatment functionality and high-temperature structural integrity, suitable for aircraft engine applications.
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 process enables the creation of dense, porous-free metal structures with improved mechanical strength and resistance to oxidation and corrosion, achieving effective acoustic absorption and kinetic energy absorption, suitable for aircraft engine applications.
Implementation Method 1
process for binding metal bodies together by sintering, in which the said bodies are heated in a high vacuum in the presence of an organic substance, at a temperature at least equal to the melting point of a eutectic between carbon and the metallic constituents of the said bodies
Implementation Method 2
at a temperature at least equal to the melting point of a eutectic between carbon and the metallic constituents of the said bodies
Implementation Method 3
An organic body, that is to say one consisting of molecules based on the chemistry of carbon, when it is subjected to a high vacuum (P<4 Pa) and to a high temperature (T>150° C.), goes from the solid (or liquid) state to the vapor state
Implementation Method 4
or by decomposition into one or more elementary substances which themselves may be converted into the vapor state
Implementation Method 5
A lightly oxidized metal element, that is to say one covered with a spontaneous layer of oxides resulting from this material coming into contact at room temperature with an atmosphere rich in oxygen and in water vapor, and brought into contact with elemental carbon under a vacuum of better than 10−4 Pa and at a temperature above 500° C., is spontaneously deoxidized
Data Source
AI summary
Hollow metal spheres are heated in a high vacuum in the presence of an organic substance, at a temperature at least equal to the melting point of a eutectic between carbon and the metallic constituents of the said spheres.