Silicon nitride (Si3N4) is a strong covalent bond compound composed of silicon and nitrogen, which has been widely produced as a ceramic material. As a typical covalent bond ceramic material, the core challenge in the development and application of silicon nitride ceramics is the sintering densification of the product. Therefore, it is necessary to add a certain amount of sintering aids to complete the densification process through liquid phase sintering. By adding different sintering aids and using different sintering processes, silicon nitride ceramic materials with different comprehensive properties can be prepared. Silicon nitride has excellent wear resistance, corrosion resistance, high temperature resistance (bending strength can reach over 350MPa at 1200 ℃), and thermal shock resistance due to its covalent bonding method. At the same time, the unique interwoven microstructure of silicon nitride columnar crystals endows silicon nitride ceramics with higher toughness, making them widely used in fields such as aerospace, national defense, military industry, and machinery.
Among the various applications of silicon nitride ceramics, bearing balls are the most widely used, accounting for three tenths of the world”s high-performance silicon nitride products in annual production. Compared with traditional steel balls, silicon nitride ceramic bearing balls have excellent properties such as low density, high temperature resistance, self-lubrication, and corrosion resistance. They are mainly used in fields such as precision bearings for machine tools, automotive bearings, insulated bearings for wind turbines, corrosion resistance and high temperature resistance bearings in petrochemical industry. In addition, due to the insulation properties of silicon nitride shafts, they are very suitable for applications in fields such as electric vehicles.
With the development of high-end equipment manufacturing industry and new clean energy, especially the wind power generation industry and aerospace industry, the usage of insulated bearings and spindle bearings used in wind turbines, as well as bearings used in aerospace engines, has significantly increased. The demand for silicon nitride ceramic bearing balls used in conjunction with them is strong.
According to incomplete statistics:
In 2019, the total global consumption of silicon nitride bearing balls reached 470 million US dollars,
In 2020, the total global consumption of silicon nitride bearing balls reached 510 million US dollars,
In 2021, the total global consumption of silicon nitride bearing balls reached 550 million US dollars, a year-on-year increase of 7.8%.
Future: With the continuous growth of demand in new energy vehicles, wind power and other fields, the market space for silicon nitride ceramic bearings is expected to further expand.
Stable Growth in the Global Argonized Silicon Bearing Ball Market
Global market size of silicon nitride bearing balls (100 million US dollars)
Bearing balls are one of the main applications of silicon nitride ceramics and have many advantages compared to traditional steel balls.
Silicon nitride ceramics are mostly composed of atomic crystals, with atoms connected by covalent bonds. Compared to metal bonds, covalent bond energy is higher, resulting in higher hardness, corrosion resistance, stable chemical properties, but poor toughness of ceramics. There is a free electron cloud near the metal bond, which does not exist in atomic crystals. Therefore, compared to metals, ceramics have stronger insulation ability and do not have conductivity.
The hardness of silicon nitride ceramics is more than twice that of steel balls, but the thermal expansion coefficient is less than one-third of that of steel balls, and the working temperature can reach 1000 ℃.
The most widely used sintering processes for silicon nitride ceramic balls are hot isostatic pressing (HIP) and gas pressure sintering (GPS), and the ceramic balls produced under these two processes are widely used in different usage environments. Among them, HIP sintering can completely densify silicon nitride ceramic balls, significantly reduce defects, and greatly improve various mechanical properties; GPS sintering can prepare products with good performance and complex shapes at a lower cost, and achieve mass production in industry.
