Keeps The Wheels Turning …
Silicon Nitride, just like its close family relation silicon carbide, is one of the toughest technical ceramics available. Over the years it has been successfully used in a wide and interesting field of applications ranging from automotive engine components to roller bearings for the most exclusive skateboards (right).
Even NASA Scientists recognised its unique properties when silicon nitride bearings were used in the main engines of the Space Shuttle. It was identified as one of the few monolithic ceramic materials capable of surviving the severe thermal shock and thermal gradients generated in hydrogen/oxygen rocket engines and proved completely reliable throughout the entire Space Shuttle programme.
Silicon nitride is a chemical compound of the elements silicon and nitrogen with the formula Si3N4. It offers many distinct advantages …
- High wear and chemical resistance
- Low friction Non magnetic
- High temperature capability
- Low specific weight
- Long service life
- High electrical resistivity
Back in one of our February blogs, we were singing the praises of silicon carbide which had found a new and novel application in the brake discs of the McLaren P1, with a price tag of £866,000 probably the most advanced and jaw-dropping road car the world has ever seen.
But like both carbides and oxides, nitrides too are very hard wearing and require diamond-grinding methods to process once fired. And just like silicon carbide, silicon nitride in particular is used for applications in which physical wear is a major consideration.
At Precision Ceramics, both silicon carbide and silicon nitride sit alongside each other in the company’s vast material stores and are used for a wide range of technical components for an equally wide field of applications.
One of the major applications of silicon nitride is in the automotive industry in the manufacture of engine parts. In diesel engines, silicon nitride glow plugs promote faster start-up, pre-combustion chambers (swirl chambers) contribute to lower emissions, faster start-up and lower noise and in turbochargers, silicon nitride helps to reduce engine lag and emissions.
In petrol engines silicon nitride is used for rocker arm pads for lower wear and in exhaust gas control valves, increased acceleration is achieved by the materials use. It is currently estimated that more than 300,000 sintered silicon nitride turbochargers are made annually!
As a bearing material, silicon nitride is also used extensively for full ceramic bearings and for hybrid ceramic bearings where ceramic balls are successfully used in conjunction with steel races.
Since silicon nitride ball bearings (left) are harder than metal, contact with the bearing track is reduced resulting in up to 80% less friction and a service life between three to ten times longer than steel.
They also afford higher corrosion resistance and allow higher temperature operation. Silicon nitride ball bearings can be found in high end automotive bearings, industrial bearings, wind turbines, bicycles, rollerblades and skateboards.
So one way and another, this unique material is helping to keep the wheels of industry turning and as far as Precision Ceramics is concerned, silicon nitride ranks high in the company’s extensive portfolio of technical ceramics.