Introduction to Silicon Nitride Ceramics
Silicon nitride(Si3N4)is a covalent compound composed of silicon and nitrogen which was discovered in 1857 and produced massively as ceramic material since 1955.Silicon nitride, especially hot pressed silicon nitride,has high strength,which is one of the hardest substances in the world.It has excellent characteristics such as high temperature resistance, acid and alkali resistance and molten metal erosion resistance, abrasion resistance, high strength and high toughness, as well as low dielectric constant and low dielectric loss.
Application of Silicon Nitride Ceramics
Silicon nitride ceramics are used in aerospace, mechanical engineering, communication, electronics, automobile, energy, chemical biology and other fields because of high temperature resistance, corrosion resistance, abrasion resistance and unique electrical performance.
In metallurgical industry:used to make parts on thermal equipment such as muffle furnace hearth,burner,crucible,mould, Aluminum liquid conduit,thermocouple protective tube,PTC fixture and aluminum electrolytic cell lining.
In chemical industry:used to make pump body, sealing ring, combustion boat, ball valve, heat exchanger parts, filter, immobilized catalyst carrier, evaporation dish, etc.
In machinery industry:used to make bearing, high-speed turning tool, supporting members for heat treatment of metal parts, rotor engine scraper, guide vanes of gas turbines, turbine blade, etc.
In aviation, semiconductor, atomic energy industries: used to make thin film capacitors, electrical insulators under high temperature or temperature upheaval, thermal conduction substrate in power semiconductor devices, switching circuit substrate, antenna housing electromagnetic wave transparent material, missile tail nozzle, isolation and support parts in atomic reactor, carrier of nuclear fission material, etc.
Medical industry: silicon nitride has excellent biocompatibility, bioactivity, bacterial resistance, bone affinity, and can provide particularly smooth and wear-resistant surface. In the medical industry, silicon nitride is the material for making surgical screws, plates and bearings and which are used in applications such as prosthetic hip, knee and dental implants. Moreover, silicon nitride composite material can also be used in cervical spacer and spinal fusion device.
Silicon Nitride Ceramic Crystal Structure
There are two main common crystal structures of silicon nitride: the α phase and the β phase. The former are needle-like crystals, being white or off-white. The latter are darker and have dense granular polyhedra or short prisms. Both structures belong to the hexagonal crystal system.
Generally speaking, high quality Si3N4 powder should have the characteristics of high α phase content, uniform composition, less impurities and uniform distribution in ceramics, small particle size, narrow particle size distribution and good dispersion. In good Si3N4 powder, there should be at least 90% α phase. Because during sintering, part of the α phase changes into the β phase. Without sufficient α phase content, the strength of the ceramic material can be reduced.
XRD in the Analysis of Silicon Nitride Ceramics
X-ray diffraction (XRD) is an essential tool for the field of materials. XRD plays an indispensable role both in analyzing the crystal structure of unknown matter and in identifying the phases of multiphase mixtures.
The α phase and β phase of Si3N4 are paramorph,whose concentration can be easily detected by the XRD technology.It provides strong data support for the research and development, quality control and production of Si3N4.FRINGE benchtop XRD is simple to operate, with high analytical speed,low detection limit and strong stability, which is very suitable for the field of silicon nitride ceramics.
Application
Use FRINGE CLASS to test and analyze customer's Si3N4 material, collect the diffraction spectrum and measure phase of silicon nitride.
After FRINGE CLASS collects diffraction spectrum, Crystal X software shows Si3N4 fine ceramic sample contains 93.69% α phase and6.31% β phase.
