Ceramic Abrasive Grain Basic and Application
General Introduction
Ceramic Alumina Abrasive, generally called “SG” is a newly developed alumina abrasive. Different from fused alumina, it is made from chemical and sintering process. Now several commercial brands have gone into the abrasive market, such as: XTL, HTB, Cubitron, CA, BCA, SG-S, TG etc.
It mainly shows white or blue color, and has sharp or blocky natural shape. Also grains with different precise shape such as rod/prism/triangular have been developed for different applications.
Ceramic alumina abrasive in the grinding process, the fracture mechanism is different from fused alumina. The core theory is continuous to create new nano level sharp blade for cutting, then the ceramic alumina abrasive can have more efficiency and more durability.
For the nano level crack feature, ceramic abrasive is fit for hard material grinding, such as aerospace alloy, hard tool steel and hard forged steel etc. And ceramic alumina abrasive can be made to different kind of grinding tool, such as bonded wheel, depress wheel, coated abrasive etc. Usually it is mixed with other grains for better cost and different applications.
Ceramic Alumina Abrasive Performance and Test Method
Different ceramic alumina abrasive from different manufacturer has slightly different performance, mainly focus on below aspect:
These parameter will directly affect the grinding performance of Ceramic Alumina Abrasive. Please refer to below table:
For abrasive grains, 3 key characters are hardness, toughness and sharpness. Below is map of different material.
When design a grinding tool, it’s needed to consider the character of different abrasive grains to achieve better performance.
Ceramic Alumina Technical Roadmap
From the ceramic alumina abrasive develop at 1980s by 3M and Norton. Actually there are two kind of technical routines. One is call “Seeded” process, Norton mainly follow this routine. Another one is “No seed” process, 3M mainly follow this direction. All of other manufacturers follow one of these routines. The difference is crystalline structure due to different chemical additive used. Detailed difference as below shows:
The production process is similar, the difference of crystalline structure is due to different additive. Below is the process of ceramic alumina abrasive.
Two crystalline structures have different application direction, for layer stack structure it has more sharpness and ball stack structure has more durability. One thing to comment the blue color of ceramic alumina abrasive is due to about 0.1% Cobalt added. Color does not affect any performance of grains. It is mainly for commercial purpose.
Ceramic Alumina Abrasive Inspection Method
For most grinding tooling manufacturers, they only have the capability to test common abrasive grains character such as appearance, particle distribution, loss pack density. For the key factor that affect grinding performance do not have capability to test. Here we introduce some easy method that can check the key characteristics.
Below is some good and bad case study:
Ceramic Alumina Abrasive Application Introduction
As the nano level fracture mechanism, ceramic alumina abrasive has advantage in application for better efficiency and longer wheel life. Usually they are mixed with fused alumina to achieve better grinding performance.
Ceramic alumina abrasives are mainly used for below applications:
Also ceramic alumina abrasives could be used for a number of other grinding applications. The manufacturer need consider the difference of each kind of ceramic alumina abrasives to balance the toughness and sharpness. And specialized bonding system is much needed for ceramic alumina abrasive tool manufacturing.
Technical Development Trend for Ceramic Alumina Abrasives
From 1980s the ceramic alumina abrasive grains was developed, there are several update of technology. At least 3 generation product was developed. The main direction is to meet the high efficiency requirement of grind tool. The roadmap is to improve sharpness and keep the toughness at certain level.
One of the direction is to make smaller crystalline size. As below pic show, the size decrease from 500nm to 50 nm. More tiny of crystalline size will improve the sharpness. And need add other additive to keep the toughness.
Another trend is to use precise forming process to make particular shape grains as below pics show:
Below is the structure of grind tool that use precise forming grains.
From Roy Material