Carburatie

Carburatie, or carburization, is a heat-treatment process used to harden the surface of steel and iron by introducing carbon into the surface layer. The diffusion of carbon creates a high-carbon case while the core remains relatively soft and tough, enabling a combination of wear resistance and structural toughness.

Most often performed at elevated temperatures in a carbon-rich environment, carburation is achieved by gas carburizing, pack carburizing, liquid carburizing, or plasma carburizing. In gas carburizing, a hydrocarbon-containing atmosphere supplies carbon potential; pack carburizing uses solid carbonaceous materials packed around the workpiece; liquid carburizing employs carburizing baths; plasma carburizing uses ionized gas in a vacuum chamber to supply carbon.

Control parameters include temperature, time, and carbon potential, which determine case depth and surface hardness. After carburizing, parts are usually quenched to form martensite in the outer layer, then tempered to reduce brittleness and set the desired hardness. The resulting microstructure comprises a high-carbon superficial layer with a lower-carbon core.

Applications include gears, crankshafts, camshafts, and other components requiring high surface hardness and fatigue resistance. Carburizing is commonly used for low- to medium-carbon steels, and can be adjusted with alloying elements to influence diffusion behavior. Limitations include energy consumption, potential distortion, and the need for subsequent heat treatment and precise process control.

Historically developed in the late 19th and early 20th centuries, carburizing remains a core method in mechanical engineering for surface hardening and wear protection. Modern variants and process controls aim to improve uniformity, efficiency, and environmental safety.