Hot Pressed Sintered Silicon Nitride
Hot Pressed sintered silicon nitride, HPSN Ceramic
Hot Pressed Sintered Silicon Nitride
To make up for the defects of the reaction sintering method, researchers sintered Si3N4 powder and sintering aids (such as MgO, Al2O3, MgF2, CeO2, Fe2O3, etc.) at high temperatures (temperatures above 1600 ℃) and high pressure (pressure above 1916 MPa). This process is called Hot Pressed sintered silicon nitride. During the hot-pressing sintering process, pressure is applied and heating is performed from a uniaxial direction so that the forming and sintering are completed at the same time. Since the external pressure increases the sintering driving force, the speed of α-β transformation and densification is accelerated, which can accelerate the rearrangement and densification of the material. If the Si3N4 ceramic material is pre-oxidized under high-temperature conditions of 1400~1500℃, the Si2N2O phase can be formed on the surface of the ceramic material, which can significantly improve the oxidation resistance and high-temperature strength of the Si3N4 ceramic.
Advantages of Hot Pressed sintered Si3N4 ceramic
The mechanical properties of the prepared Si3N4 ceramics are superior to those of Si3N4 sintered by other processes, with high density, high strength, and a short preparation cycle. High-strength silicon nitride ceramic materials with a density greater than 95% can be prepared.
Disadvantages
High-pressure equipment is required, the sintering equipment is complex, the process is complex, and the manufacturing cost is high. Only products with simple shapes can be manufactured, and the processing cost for complex products is high. Moreover, due to the existence of preferential orientation, the performance is different in the direction parallel to and perpendicular to the thermal plane.
Silicon Nitride Disc
Applications
Hot-pressed sintered silicon nitride ceramics are often used to produce ceramic products with simple shapes such as plates, sheets, ceramic tools, etc. Ceramic tool materials are very promising high-speed cutting tool materials and are widely used in production. Since silicon nitride has very high wear resistance and chemical stability, it can be cut and processed for a long time under high-speed conditions.
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