1. Silicon Nitride's modulus is 28420 ~ 46060Mpa, bending strength 147MPa, Compressive strength is 490MPa (reaction sintering), it is an important structural ceramic materials and a super-hard material, besides it has properties of lubrication, wear resistance, corrosion resistance and high temperature oxidation. And it can withstand of heated to above 1000 ℃ in the air and then cooling rapidly. For ceramic-forming Silicon Nitride needs relative low temperature but has good dimensional stability and high mechanical strength.
2. Silicon Nitride nanopowders used for Ceramic matrix compound material
Ceramic matrix compound material is prepared by the compound of multiple nano materials with ceramics as matrix. Ceramics matrix includes Silicon Nitride, silicon carbide and so on. These advanced ceramics are advantageous in high temperature resistance, high intensity and rigidity, light weight, corrosion resistance and so on, but the weak point is their high brittleness. Under the function of stress, there will be cracks and even fracture resulting in failure. The compound of nano materials and ceramics matrix is an effective method to improve the tenacity and reliability of ceramics and produce the nano reinforced ceramic compound material with excellent tenacity.
Ceramic matrix compound materials have been applied to or will be applied to tools, sliding components, engineer parts, energy components and so on. For example, the sophisticated ceramic structural components, which are compounded with silicon nitride nanoparticles, can be applied to ball bearing and roller of rolling bearing, sliding bearing, cover, valve and other structural components with requirements for wear resistance, high-temperature resistance and corrosion resistance in metallurgy, chemical industry, machinery, aviation, spaceflight and energy industry.
3. Silicon Nitride nanopowder used for Radar and Infrared Stealth Materials
The small size and quantum size effect of nano material keep more and more atoms on the surface during the refinement of metal, metal oxide and some non-meal materials, the number of dangling bonds increases, and polarization of interface is enhanced providing possibility for the application of wave-absorbing material. Multiple scattering and quantum size effect widen the energy gap of atomic polar of nano ion and the width of energy gap is within the scope of microwave (10ˉ2eV~10ˉ5eV), so it may become a new absorbing channel.
Nano ceramic powder is a new type of ceramic infrared absorbing agent, mainly including silicon carbide nanoparticles, silicon nitride nanopowders and so on. Nano ceramic infrared absorbing agent can absorb a large range of wave band and absorption strength is great. The compound of silicon carbide nanoparticles and magnetic nano absorbing agent (i.e. magnetic metal powder) will have its absorption effect improved greatly. Nano nitride absorbing agent mainly includes silicon nitride Si3N4 and Iron nitride FeN nanopowders. Silicon nitride Nanopowder has a large dielectric loss within 100Hz~1MHz, which is caused by interfacial polarization. Iron nitride nanopowder-FeN has very high saturation magnetic induction strength and saturation magnetic flux density making it possible to become an excellent nano radar absorber.
4. Special Sealing Material
Sealing surface of engine is the part with most failures and the quality of sealing surface is the dominant factor for sealing performance. Modifying the matrix of sealing parts by nano materials or covering the sealing surface with nano powders can large improve the sealing performance. At present, most of enhancing agents of sealing rubber adopt nano carbon black. If it is replaced by silicon nitride nanopowders, its tensile strength can be improved 1~4 times, as well as its abrasion resistance and leak tightness.
5. Structure devices
For example, in metallurgy, chemical industry, mechanical industry, aeronautics and space industry and energy source fields etc., the following devises can be applied: balls and rollers of roll bearings, slide bearings, covers, values and structural devices with high wear resistance, anti-high temperature and anticorrosion.
6. Surface treatments of metal and other materials
For example, moulds, cutting tools, blades of team-turbines, rotors of turbines and internal wall coatings cylinders etc.