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Ceramic Balls: Advantages & Disadvantages

Bearing means “Reduce friction by rolling rather than sliding objects.” Bearings minimize friction by supporting smoother metal balls or rollers, and a smooth inner as well as outer metal surface against which the balls roll. These rollers or balls  carry  the weight of the device, allowing it to spin effortlessly. 

Ceramic materials outperform steel in terms of corrosion and heat tolerance, more dimensional stability, and less compactness, leads to faster processing. Silicon nitride bearings are being utilized successfully in industrial tools and spindles under  vacuum, corrosive, higher temperature, hygienic, lubrication free circumstances. Based on the objective, ceramic bearings are composed of silicon nitride or silicon carbide or zirconia oxide.

Covalent bonds are formed naturally among non-metal elements in ceramic microstructures. This implies that they are sharing electrons. By this atomic cooperation, ceramics have a very powerful attraction force, which gives them a number of advantages over metals. 

Ceramic Bearings Have The Following Advantages:

  1. Corrosion Resistance: Ceramics are non-ferrous, non-metallic materials. When exposed to moisture and other harmful chemicals they don’t rust like metals would. They operate well in humid and chemically aggressive conditions because of their great corrosion resistance.
  2. Thermal Expansion: At high temperatures, they normally behave in a steady manner, as they have less thermal expansions. Whereas, with a metallic ionic bond, increasing the bond length leads to an increase in size and quality at higher temperatures, while efficiency decreases. 
  3. Lubrication: Ceramic bearings can operate without the use of lubricant. This is due to the fact that ceramic materials do not micro-weld. Micro-welding occurs when surface defects on the rolling component and raceway contact, resulting in an electric arc. The bearing life is significantly reduced as a result of this degradation. Ceramics do not have this problem, making them ideal for lubricant-free environments in a variety of applications.
  4. Density: Various engineered ceramics have lower density which leads to limited centripetal force and  decreased frictionCeramic Bearings achieve greater bearing operative speeds, and lower noise level.
  5. Hardness: These Bearings are extremely hard. Their hardness is 70-90 HRc and an elastic modulus (Young’s modulus). This indicates they have better wear characteristics and are resistant to structure change when forces are imposed, whereas, steel bearings have hardness between 60 to 66 HRc.
  6. Others:
  • Most ceramics are non-magnetic and efficient insulators because they don’t have free electrons. 
  • Ceramic bearings are ideal for a wide range of applications. They’re increasingly being employed in space exploration because they can withstand high loads, high temperature and turbulent environments while also helping to alleviate the weight limits of lunar transit.

Disadvantages:

Considering all of the advantages! I’m sure you’re astounded, and you’re probably wondering, “Shouldn’t these wonderful materials be used in every bearing?” Unfortunately, there are some drawbacks as well.

  1. Load Capacity: Ceramic bearings have lower load capabilities and are more susceptible to thermal stress than metallic bearings. Thermal shock occurs when a material’s temperature gradient produces asymmetrical expansion resulting in internal tension. This stress may be greater than the material’s strength, resulting in a crack/splits. 
  2. Cost: When examining ceramic bearings, the first thing that people may notice is that they are substantially more expensive than their metal equivalents. This is due to a variety of factors, Such as:
  • Extremely high temperatures required for the sintering procedure, as well as the exceptionally high cost of raw materials. 
  • Very high purity of raw material is required because even minor contamination would significantly lower bearing life. 
  • High ceramic hardness raises the cost of grinding and lapping procedures. 
  • In Addition, the cost of the technology used to make the ceramic balls is likewise very high.

References:
https://www.bcprecision.com/blogs/news/71278725-advantages-and-disadvantages-of-ceramic-bearings
https://www.ortechceramics.com/ceramic-bearings-vs-steel-bearings/