Silicon nitride ceramics have high-temperature resistance, corrosion resistance, wear resistance, and unique electrical properties and are considered one of the most promising high-temperature structural ceramic materials.
The mechanical structure of the future aero-engine will be simpler than the existing type, with fewer components, and operating at a higher turbine inlet temperature and component load. Its reliability and component life will also be improved. Turbine materials must meet the requirements in terms of tensile strength, creep resistance, high-temperature corrosion resistance, and impact damage resistance. The use of ceramic materials with better thermal performance can reduce the amount of cooling air required and significantly increase the gas temperature.
In the past, large aircraft engines mainly used nickel-based high-temperature materials, and silicon nitride materials have higher strength, better creep strength, and oxidation resistance than nickel-based heat-resistant alloys at temperatures above 1000°C and have a small specific gravity. It is only 40% of the heat-resistant alloy, which can meet future aviation engines’ requirements to reduce weight and fuel consumption.
Silicon nitride ceramics can be used as turbine blades, mechanical seal rings, high-temperature bearings, high-speed cutting tools, permanent molds, etc. in the machinery industry. Many devices in the traditional machinery industry use metal materials. Since the metal will be corroded, the reliability and service life of these devices is greatly affected. Silicon nitride ceramic materials have excellent wear resistance, corrosion resistance, and high-temperature thermal shock resistance. Can replace metal materials in the field of machinery industry.
For example, silicon nitride can be used to manufacture ball bearings with lightweight and high rigidity. It has higher precision than metal bearings, generates less heat, and can operate in higher temperatures and corrosive media. The steam nozzle made of silicon nitride ceramics has the characteristics of wear resistance and heat resistance, and no obvious damage after being used in a 650°C boiler for a few months, while other heat resistance and corrosion-resistant alloy steel nozzles can only be used for 1-2 months under the same conditions.
Silicon nitride ceramics are covalent compounds whose bonding mainly relies on covalent bonds between atoms, and the prepared material itself has high hardness and wear resistance. Silicon nitride has high hardness, second only to a few super hard materials such as diamond and cubic boron nitride, and has low friction coefficient and self-lubricating properties. In the ultrafine powder and food processing industries, silicon nitride ceramic grinding balls’ performance is higher than traditional grinding balls, with higher hardness and superior wear resistance.
With the rapid development of information technology, integrating integrated circuits is getting higher and higher, and the wiring density is getting higher and higher. If the electronic package substrate cannot dissipate heat in time, a large amount of heat will accumulate on the integrated circuit, which will eventually lead to its failure and damage. Therefore, the thermal conductivity of the substrate is extremely important. Silicon nitride ceramics are structural ceramic materials with the best comprehensive performance. The theoretical thermal conductivity of single-crystal Si3N4 can reach more than 400W· M-1, which has the potential to become a high thermal conductivity substrate. Due to its excellent mechanical properties and high thermal conductivity potential, Si3N4 ceramics are expected to make up for the shortage of existing aluminum oxide, aluminum nitride, and other substrate materials that have a great market prospect in the application of electronic packaging substrate.
Silicon nitride ceramic materials have excellent chemical stability and excellent mechanical properties. They can be used as components on thermal equipment such as crucibles, burners, aluminum electrolytic cell linings, etc. in the metallurgical industry. Silicon nitride ceramics have good oxidation resistance. The oxidation resistance temperature can be as high as 1400°C. It is stable in a dry oxidizing atmosphere below 1400°C, and the use temperature can reach 1300°C. And silicon nitride material can be used in the environment of rapid cold and rapid heat, so it also has a very wide range of applications in the metallurgical industry.