Britannica Sources used in this answer

How do welding, brazing, soldering, and adhesive bonding join materials?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

electron hole: movement — materials science Movement of an electron hole in a crystal lattice.

In materials science, joining techniques are categorized by how they achieve cohesion between components.

Welding

Welding involves the coalescence of metals, typically through heat, with or without pressure or filler material. In fusion welding, a heat source creates a molten pool of metal that solidifies to form a joint. Conversely, solid-phase processes join materials without melting the base metal, relying instead on pressure and sometimes heat.1

Brazing and Soldering

Both brazing and soldering join metallic surfaces by using a filler metal with a lower melting point than the base materials, without melting the base metals themselves.23
* Brazing: Performed at temperatures exceeding 800° F (430° C), often utilizing capillary action to draw filler into the joint.3
* Soldering: Performed at lower temperatures than brazing. It relies on thorough surface cleaning and the use of flux to remove oxides and promote wetting.32

Adhesive Bonding

Adhesive bonding joins materials through interfacial molecular contact. The process requires the adhesive to wet and spread across the surfaces, creating bonds through mechanisms such as adsorption (intermolecular forces), mechanical interlocking, interdiffusion, or chemical reactions.4