Deposition occurs when bits of Earth that were carried away by erosion are deposited elsewhere – this process forms river beds, flood plains and oxbow lakes.
Physical and chemical vapor deposition (PVD and CVD) occurs under far from equilibrium conditions; thus statistical mechanics centered around equilibrium cannot accurately predict film growth.
Erosion and Deposition
Erosion occurs when bits of rock and soil are worn away by natural forces such as wind or water. This process stands in contrast to deposition, when these particles are dropped in new places to build landforms.
Wind, gravity, water, and ice all carry weathered surface materials from one location to the next, until they can no longer gain momentum and are eventually deposited as they cease to gain energy from moving further.
Erosion and its result, sediment, are closely connected processes; erosion involves loose material being carried off into water by wind currents while its deposits become sediment. Sediments consist of rocks, gravel, sand or silt deposits which have formed. While in some instances like with igneous rocks these materials are held together by strong bonds; in other cases like with sedimentary rocks these bonds are much weaker and easily broken apart.
Deposition, the process by which substances transition directly from gaseous form into solid form, can also occur directly; for instance, turning water vapor into frost on windows or leaves would be considered deposition.
Changes in the Environment
Deposition in chemistry refers to a phase change that transforms gases directly into solids without passing through liquid phase, such as frost forming on surfaces or snow formation from clouds.
Wind, ice and water transport previously weathered surface material to form sediment layers. When erosion agents run out of energy (kinetic or gravity), they stop moving and start depositing the material instead.
Glaciers that erode and deposit sediment onto mountain slopes often lose momentum as their deposits no longer contain enough kinetic energy to transport the materials that were once in their path; once that happens, layers start accumulating on slopes and flat areas of their environment.
On a global scale, adverse environmental changes due to human-generated emissions of heat-trapping greenhouse gases are occurring at an unprecedented pace, leading to rising atmospheric temperatures that have already led to glaciers melting off, ocean levels rising and animal and plant migration patterns changing drastically.
Chemical Vapor Deposition
Chemical vapor deposition (CVD) is one of the most frequently employed coating methods, making use of its unique process allowing coating of metals, polymers and ceramics.
CVD requires volatile precursor gases to be introduced into a reactor chamber with heated objects to be coated, where they decompose on their surfaces to deposit a film and create byproducts that must then be evacuated from the chamber along with unreacted gases.
By-products may include either original reagent chemicals or short-lived intermediate species created during high temperature gas phase reactions. CVD differs from Physical Vapor Deposition (PVD) by being an exothermic reaction-based process rather than exothermic evaporation or sputtering-based deposition method.
Low pressure CVD (LPCVD) employs a pump to draw gases away from substrates to limit unwanted gas-phase reactions and ensure uniform deposition. It is most often used to deposit parylene, an ideal coating resistant to moisture, acids, alkalis and petroleum products.
Physical deposition (PVD) is an increasingly popular coating technique that allows coatings to be applied over various types of materials, with the goal of improving both their tribological behavior and aesthetic appearance. PVD technology is especially relevant for tool makers as it coats tools with hard ceramic coatings such as titanium nitride and chromium nitride to extend tool lifespan and enhance performance.
PVD (Physical Vapor Deposition) involves solid materials being vaporized in a vacuum and transported and deposited on substrate surfaces via physical transfer, as opposed to CVD which uses gas phase precursors already in their gaseous state and does not rely on physical transport for deposition. Vaporization can be accomplished via methods like sputtering, thermal evaporation and electron beam physical vapor deposition techniques that achieve pollution-free deposition – making PVD an increasingly appealing choice in today’s environmentally responsible society.