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Have you ever seen such a structure of porous metal?



10.05.2019 22:33:56 - Porous aluminium versus sintered metal.

(live-PR.com) - Structure comparison of porous aluminum and sintered metals:
Porous aluminum is produced by casting with salt. This technology offers a unique structure of the porous metal. The structure of porous aluminum and the structure of well known sintered metals are complementary.
The pores in the sintered metal correspond to the metal in the porous aluminum and vice versa. Theoretically, the minimum volume

 

porosity of the sintered metals is 26% and the maximum volume porosity of the porous aluminum is 74%. Practically, porous aluminum has 50-55% pores due to imperfect stacking of salt particles.

Shape and size of the pores:
Two types of salt granules are used for the production of porous aluminum, either spherical salt or break salt.
The properties of porous aluminum depend very much on the size of the pores. We use 7 different salt fractions to obtain porous material with very different properties. This allows us to offer the optimal product for every task.

Connection between the pores:
In the production of porous aluminum, each salt particle has many contact points with other salt particles. The surface tension prevents molten aluminum to get between two salt particles. Therefore, all salt particles and then all the pores are connected to each other. All pores are open, so porous aluminum is permeable throughout the whole volume and in all directions.

Liquid and gas flow in porous aluminum and in sintered metal:
The particular structure of the pores in porous aluminum results in a different flow of liquid or gas than in the pores of the sintered metal. Such flow increases the efficiency of the use of porous aluminum in such applications as heat exchange, filtration and silencing.

Porous aluminium and sintered metals are both open-celled and therefore permeable, but the manufacturing technologies and thus the structure of the materials are different.

In our manufacturing process of porous aluminium, the liquid aluminium is cast together with crystal salt, and after mechanical finishing the salt is washed out. The salt grains and their contact points are thus replaced by pores. In the case of sintered metals, the metal grains will agglomerate. The voidage between the granules defines the pores. Therefore, the principle is just the opposite. Where sintered metals have a metal grains, porous aluminium has pores. In our porous aluminium the pores are formed in place of the salt crystals and the empty space in the crystal salt is filled with metal.

Porous metals play an important role in modern technology. Filters and filter elements, journal bearings, silencers, fire breaks etc. of various metal powders are manufactured according to the method of powder metallurgy (powder metallurgy materials), the so-called sintering technology (sintered metal). Permeable materials with high stability and high volume porosity produced by sintering technology are usually made of bronze, copper and steel.

Aluminium has equally high heat conductivity and electrical conductivity properties but also low density and good corrosion resistance, thereby offering several advantages over bronze, copper and steel. However, it is difficult to produce porous materials from aluminium using sintering technology.

The following problem arises in the production of sintered aaluminium: Aluminium powder reacts quickly and oxidizes the aluminium grains with non-melting oxide Al2O3. The temperature, at which the oxide wrapping dissolves, is somewhat higher than the melting temperature of aaluminium. This temperature also depends on the size of the aluminium grains and the thickness of the oxide layer. Although in theory there are several methods for solving this problem, it is not yet possible to produce aluminium products with high volume porosity and adequate strength by the technology of sintering. We provide a solution – porous aluminium.
Advantages over sintered metals:

– Sintered aluminium is difficult to produce
– Volume porosity of porous aluminium is about 55%. Sintered metals have volume porosity level of 30-35%
– Thanks to cast stucture, porous aluminium has a high mechanical strength and is free of crumbling. Sintered metals are relatively fragile.


Press Information:
Exxentis Ltd

Schartenfelsstrasse 6, 5403 Wettingen, Switzerland

Contact Person:
Olga Mühldorfer
Techn. Sales
Phone: +41564300300
eMail: eMail

Web: http://https://www.exxentis.co.uk/



 

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