Ceramic materials respond differently to stresses imposed by moving mechanical contact. Some might experience wear and tear, others may break down, while others merely peel off the surface.

This article discusses how to measure a ceramic material’s behavior to opposing forces and factors affecting the behavior. We also discuss issues like ‘wear resistance has a direct or proportional relationship with sliding distance and contact load.’

Many ceramic industrial applications are high-risk, so knowing the extent a ceramic material resists wear beforehand is important.

What is Wear Resistance Testing?

Wear resistance testing is a measure of the response of the ceramic material surface to friction or opposing force. These tests assess how well a ceramic material performs in processes involving abrasive action, friction, and wear. A.K.A. the tribological performance of ceramics.

Ceramic testing methods include Taber abrasion, pin-on disk wear, scratch test method, ball-on-disk method, etc. 

Ceramic Testing Methods

How do you measure wear resistance?

1. Taber Abrasion Technique</h3>

The Taber Abrasion technique is a relatively simple testing method with an internationally recognized ceramic testing standard, ISO 4649/ DIN 35516.

During the test, the abrasive sheet is mounted on a revolving drum. The operator then moves a piece of rubber across the abrasive sheet to find the volume loss. Depending on the rate of wear, the test results will give higher or lower figures.

The lower the figures, the better the wear resistance. Meaning, high figures represent a high wear rate, which translates to poor wear resistance.

2. Pin-On-Disk Wear Test

This is considered one of the most preferred wear resistance ceramic testing methods. It involves sliding a ceramic pin on a rotating disk (which is usually made of another material).

The operator runs the rotating disk at a controlled speed and load. He then assesses the rate of wear and volume loss after a given number of cycles.

The pin-on-disk wear technique simulates general service conditions, testing for fretting, abrasion, and adhesive action. However, it may not fully simulate severe working conditions.

3. Scratch Test Method

The Scratch test method uses a tip or indenter to simulate such wear types as cutting, grooving, and plowing. This is why tips come in different sizes and shapes.

An operator drags a hard tip across a ceramic surface at a controlled speed and load. Hence, he measures the critical load or depth at which the surface cracks.

The Scratch test method focuses on evaluating the adhesion of ceramic films and fracture toughness. However, it may not do as much as to evaluate the effects of fatigue on wear performance.

4. Ball-On-Disk Method

The ball-on-disk method is yet another prominent technique for measuring wear resistance. It involves sliding a spherical ball (of a different material) at a controlled speed and load.

The operator slides the ball against a flat ceramic disk for a few cycles. He then assesses the disk to calculate the amount of wear caused, depending on the depth of the wear scar.

This method is relatively versatile. It can simulate different types of wear by rolling, sliding, or changing the direction of ball movement. 

The method is curated to test the hardness and surface finish of the ceramic disk. It may not assess the wear behavior caused by factors like temperature or lubrication.

What is the Relationship Between Ceramic Wear Resistance and Hardness?

Does wear resistance mean hardness? Or… Is there a direct link between them?

It’s not uncommon to say a hard ceramic material can withstand any kind of wear. That’s also what researchers first said. But they later discovered something interesting!

In early research, physicists believed that the hardness and wear resistance of ceramics always had a direct connection. As in, the hardness of a ceramic material always translated to better wear resistance.

However, further research unveiled that wear resistance boils down to a ceramic material’s microstructure, grain boundary toughness, and grain size and shape. Meaning, there was more to the wear resistance dynamics than was earlier thought!

The wear resistance mechanism also turned out to be different from hardness dynamics at the microstructure level. Hardness relies on how strong the grain boundary bond is. On the contrary, wear resistance requires the material to break away from the wear surface.

For instance, comparisons between the hardness and wear resistance of alumina ceramics and TZP zirconia ceramics showed this contrast. While alumina ceramics are typically harder than TZP zirconia, the latter has better wear resistance than alumina.

This also sidelined the ordinary belief that wear resistance was merely determined by external operating conditions.

Therefore, testing the wear resistance of ceramic materials needed a slightly different approach from hardness tests. Ceramic wear testing methods are now guided by the ceramic wear dynamics and factors influencing them.

But it’s worth noting that some ceramic materials have both high wear resistance and hardness when compared to their counterparts. We’re simply saying that wear resistance and hardness of ceramics don’t always relate directly and have to be tested independently.

Factors Influencing the Wear Resistance of Ceramic Materials

Testing wear resistance of ceramic materials is influenced by internal and external factors.

Internal factors affecting ceramic wear resistance include grain boundary, porosity, and size and shape.

Whereas external factors simply mean the conditions ceramic materials are subjected to in the ceramic testing laboratory.

• Grain Boundary

Usually, many ceramics are polycrystalline, which means they are composed of many crystallites or grains. The region between two grains is called a grain boundary. However, the region between the grains is called a phase boundary if they exhibit different properties, such as chemical composition.

So, how does this affect a ceramic material’s wear resistance?

During sintering, a high-temperature process during injection molding, ceramics experience intercrystalline impurities due to additives. This occurs because of the presence of the glassy phase between the grains, reducing their bonding strength. With lower bonding strength, cracks form at the grain boundary.

Serious wear occurs on the whole grain during friction and abrasion. The abrasive action produces even more heat, which affects the viscosity of the glass phase and eventually causes plastic deformation.

A good amount of additives and toughening aids play a key role in improving the wear resistance of a ceramic material. Otherwise, the adjacent grain boundary may experience serious wear due to a lack of a suitable amount of stress.

• Porosity

When evaluating wear resistance, porosity is considered a deformity that affects the ceramic’s bonding strength. Besides, a pore provides more room for fault lines to form, hence greatly affecting stress concentration.

When abrasive force is applied, pores make it easy to form fractures, hence aggravating wear and tear. Meaning, the less porous a ceramic material is, the more wear resistant it is likely to be.

• Size

Ceramic manufacturing involves careful selection of ceramic materials. One parameter is a material’s grain size. Small-grained ceramics tend to have greater intergranular bonds and better mechanical properties. However, bigger grains are brittle and more likely to wear during friction.

External Factors

As already stated, external factors affecting ceramic wear resistance are the environmental conditions of the ceramic testing laboratory. Such factors include corrosion, external impact, and temperature and pressure.

• Corrosion: Ceramic materials may come into contact with components that have corrosive agents. If exposed to such environments for long, ceramic materials may erode or peel off. Their crystalline structure and bonding strength may also tone down.

• External impact: This includes vibration and collision that happen during operation. Such forces may affect a ceramic’s structure and surface. The particles may also loosen and their surfaces peel, accelerating the wear.

• Temperature and pressure: Many technical ceramics can withstand extreme temperature and pressure. However, they may lose their structural integrity and start to break down if the conditions are set to extreme levels.

Wear Resistant Ceramic Materials and Their Applications

Advanced ceramic materials are among the most promising materials for machinery and technical industries. Combined with their chemical stability, high melting temperatures, and elastic modules, they exhibit exquisite tribological properties.

Other properties include high fracture toughness, high hardness, and exceptional heat resistance. As such, wear resistant ceramics are applicable in a wide range of industry applications, as shown in the table below:

Why GORGEOUS is a Reliable Wear Resistance Ceramic Manufacturer

GORGEOUS is one of the most promising advanced ceramics producers in China, amassing positive reviews for its legitimate products and transparency.

With all-around products and services, GORGEOUS provides all your advanced ceramics needs. We cut across such industries as aerospace, medicine, chemistry, aerospace, automotive, electronics, and engineering.

Talk about raw material preparation, injection molding, sintering, surface treatment, and inspection. Just send us a quote and we’ll deliver!

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