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Article: Scratch hardness

Scratch hardness

Definition and Importance of Scratch Hardness

  • Scratch hardness refers to the resistance of a material to scratches and abrasion by a harder material drawn forcefully over its surface.
  • It is measured using a sclerometer and is less affected by surface variations compared to indentation methods.
  • Scratch hardness tests have been used for a long time to quantify materials.
  • Friedrich Mohs developed the first scientific attempt to measure scratch hardness in 1812, known as the Mohs scale.
  • The Mohs scale is based on the relative scratch hardness of different materials, with talc assigned a value of 1 and diamond assigned a value of 10.

Limitations and Modifications of the Mohs Scale

  • The Mohs scale had two limitations: it was not linear and most modern abrasives fall between 9 and 10 on the scale.
  • Raymond R. Ridgway modified the Mohs scale by giving garnet a hardness of 10 and diamond a hardness of 15.
  • Charles E. Wooddell extended the scale further by using resistance to abrasion and extrapolating the scale based on 7 for quartz and 9 for corundum.
  • Wooddell's scale resulted in a value of 42.4 for South American brown diamond bort.
  • There is a linear relationship between cohesive energy density and Wooddell wear resistance, occurring between corundum (H=9) and diamond (H=42.5).

Scratch Hardness Test Methods

  • Scratch hardness test refers to any of a number of methods used to measure scratch hardness.
  • These methods aim to quantify the resistance of a material to scratches and abrasion.
  • The sclerometer is commonly used to measure scratch hardness.
  • The scratch test involves forcefully drawing a harder material over the surface of the material being tested.
  • The results of the scratch hardness test can provide valuable information about the durability and wear resistance of materials.

Applications of Scratch Hardness

  • Scratch hardness testing is widely used in various industries, including materials science, engineering, and manufacturing.
  • It is used to assess the hardness, durability, and wear resistance of materials.
  • Scratch hardness tests help in the selection of appropriate materials for specific applications.
  • The results of scratch hardness tests can be used to compare and rank different materials based on their resistance to scratches and abrasion.
  • Scratch hardness testing is crucial in industries such as automotive, aerospace, and construction, where materials need to withstand harsh conditions.

Further Research and Development in Scratch Hardness

  • Ongoing research aims to improve the accuracy and precision of scratch hardness testing methods.
  • Scientists are exploring new techniques and instruments to measure scratch hardness.
  • The scalability of scratching for different probes and depths opens new avenues for miniaturization and extracting fracture properties of materials at smaller length scales.
  • The relationship between scratch hardness and other material properties, such as fracture toughness, is an area of active research.
  • Advances in scratch hardness testing can contribute to the development of more durable and wear-resistant materials for various applications.

Scratch hardness Data Sources

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