povlak

Povlak is a layer of material applied to the surface of an object to modify its properties or appearance. The term is used in materials science to describe protective, functional, or decorative coatings. In everyday Czech usage, povlak can also refer to dental plaque (zubní povlak), a biofilm on teeth.

Coatings are classified by purpose. Protective coatings aim to prevent corrosion, wear, or chemical attack; functional coatings change properties such as electrical conductivity, friction, or optical behavior; decorative coatings provide color and texture. Common coating materials include metals (zinc, chromium, nickel), polymers (epoxy, polyurethane), ceramics (alumina, silicon carbide), and composite systems.

Coatings are applied by various methods, including painting, spraying, electroplating and galvanizing, thermal spraying, and deposition techniques such as physical vapor deposition (PVD) and chemical vapor deposition (CVD). Other methods include powder coating, dip coating, spin coating, and brush coating.

Important coating properties include adhesion to the substrate, thickness and uniformity, hardness, wear and corrosion resistance, thermal stability, and surface roughness. Quality assessment uses standardized tests and guidelines from ISO and ASTM.

Coatings are widely used in automotive, aerospace, electronics, energy, medical devices, and construction. In dental contexts, povlak refers to plaque, a biofilm that forms on teeth and requires mechanical removal and hygiene practices to control.