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 nyone, though, who believes that mother's best porcelain from the china cabinet is being fitted under the bonnet, is greatly mistaken. For the ceramics which are of interest to the engine designer have nothing in common with the natural product.
Ceramic engine valves in the Bayer research centre in Germany
 xcept for one thing: engineering or material ceramics are brittle - as the technicians say. Or breakable, as is generally known of porcelain. But this has its good points. Ceramic material is not elastic: it does not yield. Up to the point where it does, however, by abruptly shattering, it can stand a considerable amount of loading.
Ideal properties, then, for engine design, where rigid construction is the order of the day. Ceramics are already in use in catalyst carriers, water pump sealing washers and rotors in turbochargers. Every car maker in the world has for years been running field trials with valves or generally with components in the valve operation chain, such as rocker arms or valve lifters.
This is where a further advantage of engineering ceramics becomes apparent: their high heat resistance. All of this once again copied from nature: after all, plates and cups do not crack in the oven or in a hot dishwasher, although the temperature level in an engine is, of course, several times higher.
 
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Accordingly, as a synthetically produced laboratory product, which is taken from its original form as a powder and sintered, i.e. "baked" into a solid, the ceramic material can be cultivated to the requirements of the engineers: its good chemical, thermal and wear resistance properties allow conventional ideas to be challenged and new approaches made to solutions for the so desperately needed weight-saving in the engine.
For ceramic materials are only half as heavy as steel. If ceramics were to replace steel in a multi-valve engine, then in the case of a four-cylinder, four-valve engine, each one of the 16 valves could be reduced, for example from 50 g to 25 g, multiplied by 16 equals 400 g of precious weight reduction.
Mercedes-Benz is already testing ceramic valves in their 3-litres 24-valves engine
 f course, no material can be replaced by another in the ratio 1:1 - this has been the greatest mistake. Not least for this reason, ceramics research is still on the starting blocks, and know-how in the handling of this high-tech product takes a long time and is expensive to develop. And finally, different design parameters apply to ceramics from those applying to steel, to enable it fully unfold its advantages.
This is also the answer to the question of the porcelain cylinder head: it would certainly be a pretty sight - it is just that nobody would be able to afford it!
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