Capsule bottom

Schematic representation of the capsule bottom. Illustration of the hob surface, aluminum core and cookware base.

Cross-section of a capsule base in a stereo microscope.

Hardness test on aluminum core. (Capsule bottom of a pan)

The capsule base , also called encapsulated thermal base , is an expanded form of the multi-layer base (sandwich base). It is used for stainless steel cookware . The bottom of the capsule has a core made of aluminum or copper, which conducts the heat better than a bottom made of stainless steel of the same thickness. The capsule protects the aluminum from tarnishing and the food from reacting with the copper .

Structure of a capsule base

The capsule base consists of three layers:

1. Thin capsule base (thin layers of stainless steel)
2. Stronger core made of aluminum or copper . Due to its good thermal conductivity, the core ensures an even heat transfer to the food.
3. Thin cookware base (upper capsule layer) made of stainless steel .

The two thin layers of stainless steel cover the core, which is a good heat conductor, preventing its corrosion and warping of the bottom of the pot.

Capsule Bottom Materials

Aluminum or copper and stainless steel are used for the capsule base . The structure of the capsule base is similar to that of the sandwich base. Multi-layer floors can also consist of only two layers of copper and stainless steel. Pans with such bases are also offered with an additional layer of polytetrafluoroethylene (PTFE, "Teflon") non-stick coated on the inside .

Material investigation

Chromium-nickel steels are usually used for capsule bottoms because they are rust-free and can be heated up to 300 ° C. In the pan under investigation (see picture "Cross section of a capsule bottom in a stereomicroscope"), an X5CrNi1810 steel was used for the bottom of the cookware and an X5Cr17 steel for the stove top surface.

Usually pure aluminum is used as the core , the thermal conductivity of which is 236 W / (mK, as it is much cheaper than copper with a thermal conductivity of up to 401 W / (mK). (For comparison: the austenitic , stainless steel X5CrNi18- 10 has 15 W / (m · K), unalloyed steel up to 58 W / (m · K)).

A Vickers hardness test was carried out in the illustration on the right . The hardness value of the aluminum core is 48.5 HV 0.01.

Web links

Commons : Capsule Bottom  - Collection of pictures, videos and audio files

Individual evidence

1. ↑ Capsule bottom
2. ↑ TÜV report
3. ↑ Stainless steel material overview. (No longer available online.) Archived from the original on April 5, 2016 ; accessed on August 4, 2017 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  
4. ↑ Dr.-Ing Ulrich Heubner: Leaflet 821; Stainless steel properties . 5th edition. Werdohl 2014.