Light Material For High Temperatures

2023 Author: Hannah Pearcy | [email protected]. Last modified: 2023-06-01 01:49

Silicon nitride, a high-performance ceramic called Si ₃ N ₄, belongs to the group of non-oxide ceramics, which are characterized by exceptional technological properties. As a relatively young material, it was only brought to industrial maturity in the second half of the last century. At that time it was a matter of finding an alternative to metallic materials in turbines and internal combustion engines for certain components exposed to high mechanical and thermal loads in order to be able to achieve higher operating temperatures and thus higher efficiencies. Due to the high demands on processing, from the production of the powdered raw materials to the shaping to sintering and the associated high costs, the material has so far been mainly used for special applications.

Properties and application

Silicon nitride has a low density of 3.2 to 3.3 g / cm³ and is therefore almost as light as the light metal aluminum with 2.7 g / cm³, the bending strength is up to 1000 MPa. Si ₃ N ₄ is also characterized by high wear resistance and has better high temperature properties than most metals, which also include high temperature resistance and creep resistance. Other special features are a low coefficient of thermal expansion and thus a very good resistance to temperature changes (thermal shock resistance) as well as high fracture toughness (7 MPa m ^1/2). Workpieces made of Si ₃ N ₄are therefore insensitive to bumps and blows. These components can withstand operating temperatures of up to 1300 ° C, are resistant to corrosive effects and chemicals such as strong acids and alkalis as well as certain molten metals such as aluminum.

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Because of all these properties, silicon nitride is ideal for components that have high mechanical strength - even under sudden stress - and that have to endure high operating temperatures, corrosive media and wear-resistant loads. Examples of applications include components for internal combustion engines, engines and other energy and chemical systems, highly stressed seals and bearings of all kinds, pump wheels for aggressive media, guides for continuous goods such as wire, fibers and threads, as well as cutting and cutting tools for materials that are difficult to machine. In this case, it is remarkable that the processes can be carried out without cooling lubricant and at maximum speed. Other application examples are tools for metal forming and foundry technology,which have a significantly longer service life than steel components.

Process know-how in demand

The ceramic specialist Sembach has many decades of experience in the design, shaping and production of workpieces made of high-performance ceramics. With its modern production equipment, Sembach is able to economically manufacture prototypes as well as large series parts from sintered silicon nitride (SSN) using injection molding, dry pressing and machining with a 5-axis milling machine. (qui)