Kratzfeste

Kratzfeste describes the property of a material or surface to resist scratching. It is used for adjectives such as kratzfest or kratzfeste Oberfläche and is often discussed in the context of coatings, glasses, and plastics. Scratch resistance results from a combination of hardness, toughness and the presence of protective layers or surface treatments.

Mechanisms and approaches: Higher surface hardness, typically measured on scales of Mohs or Vickers hardness, reduces the likelihood of scratch initiation. In practice, scratch resistance is enhanced by protective coatings made of ceramics (for example Al2O3, TiN, ZrO2), diamond-like carbon, or multilayer coatings, as well as by hard, tempered or synthetic sapphire substrates. Tempered glass or laminated glass can also improve scratch performance. Toughness and adhesion of the coating to the substrate are important to prevent cracking or delamination after a scratch.

Testing and standards: Scratch resistance is commonly assessed with pencil hardness tests (ASTM D3363) to identify the hardest pencil that does not mar the surface, and with progressive-scratch or nano-scratch tests that determine the critical load at which damage occurs. Wear-related testing, such as Taber abrasion, is sometimes used to evaluate long-term surface durability.

Applications and limits: Kratzfeste surfaces are sought after in consumer electronics (screen glass), automotive finishes, kitchenware, and optical lenses. However, increased hardness can come at the cost of brittleness, and exceedingly hard surfaces may still be damaged by hard particulates or improper cleaning. Real-world scratch resistance depends on material properties, coating quality, surface roughness, and maintenance.