Process for the Powder Metallurgy Production of Metal Foam and of Parts Made from Metal Foam

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This patent discloses a process for producing metal foam and parts made from metal foam using powder metallurgy techniques. The invention eliminates the need for foaming agents by controlling pressure within a sealed chamber. The metal powder is first compacted, then heated to its melting or solidus temperature under a set initial pressure. Once at temperature, the chamber pressure is reduced at a controlled rate, causing the compacted metal to foam and then solidify as it cools. This allows precise control over pore size and foam expansion, resulting in uniform, high-quality metal foams.

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• Automotive parts requiring lightweight yet strong materials, such as structural components or impact absorbers
• Aerospace applications for lightweight panels and insulation
• Construction materials for soundproofing, vibration damping, or fire-resistant panels
• Thermal management components, such as heat exchangers or dissipative panels
• Medical implants or devices benefitting from porous, biocompatible metal structures
• Energy absorption in crash barriers or protective equipment
• Filtration systems using metal foam for fluid or air filtration

BenefitsContent extracted from patent full text and abstract with AI.

• No need for additional foaming agent additives, reducing material costs and contamination
• Allows for accurate tuning of pore size and foam expansion through pressure management
• Can achieve highly uniform pore size distribution for predictable material properties
• Process is versatile and can be applied to different metals and alloys
• Potentially simplifies production equipment compared with methods requiring gas injection or added agents
• Improved reproducibility and dimensional accuracy of final parts
• Enhanced energy absorption, thermal conductivity, and structural integrity due to uniform pores

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Patent Abstract

The invention relates to a process for the powder metallurgy production of metal foam and of parts made from metal foam. In known powder metallurgy processes, foaming agent particles are admixed with the metal particles and form gas bubbles on heating. This results in the formation of unevenly distributed cells of different sizes in the metal foam. The cell size and the volume expansion are difficult to control during the process. In the process according to the invention, the metallic material in powder form, which has been pressed under mechanical pressure and at a temperature of up to 4000°C to form a dimensionally stable semi-finished product, is heated, in a chamber which has been closed in a pressure-tight manner and at a selected initial pressure which is preferably up to 50 bar, to the melting or solidus temperature of the metallic material in powder form. After the melting or solidus temperature of the metallic material in powder form has been reached, the pressure in the chamber is reduced, at a predetermined gradient, to a final pressure which may be lower than 0.1 bar. This causes the semi-finished product to foam, and the metal foam formed in this way solidifies during the subsequent drop in temperature. It is also possible to produce accurately dimensioned metal foam bodies if suitable shaping moulds are used. The advantage is that there is no need to admix any foaming agent particles, and by using settable initial and final pressures it is possible to set the cell size and the volume expansion within certain limits with simple and accurate selection and/or during the course of the process.