Plasma spraying, one of the thermal spraying family, is a materials processing technique for producing coatings and free-standing parts using a plasma jet. Deposits having thickness from micrometers to several millimeters can be produced from a variety of materials - metals, ceramics, polymers and composites. A coating is a covering, usually liquid, that is put on to protect, or change the appearance of something. ... The word plasma has a Greek root which means to be formed or molded (the word plastic shares this root). ... Hot metal work from a blacksmith In chemistry, a metal (Greek: Metallon) is an element that readily forms ions (cations) and has metallic bonds, and metals are sometimes described as a lattice of positive ions (cations) in a cloud of electrons. ... The word ceramic is derived from the Greek word Κεραμεικος (the name of a suburb of Athens), and in its strictest sense refers to clay in all its forms. ... Polymer is a generic term used to describe a very long molecule consisting of structural units and repeating units connected by covalent chemical bonds. ... Composite materials (or composites for short) are engineering materials made from two or more components. ...

How it works

The material to be deposited - typically as a powder, rarely as a liquid, suspension or wire - is introduced to the plasma jet, emanating from a plasma torch. In the jet, having temperatures of the order of 10 000 K, the material is melted and propelled towards a substrate. There, the molten droplets flatten, rapidly solidify and form a deposit. Commonly, the deposits remain adherent to the substrate as coatings; free-standing parts can also be produced by removing the substrate. There is a large number of technological parameters that influence the interaction of the particles with the plasma jet and the substrate and therefore the deposit properties. Powder is a substance that has been crushed into very fine grains. ... A liquid will assume the shape of its container. ... Flour suspended in water In chemistry, a suspension is a dispersion (mixture) in which a finely-divided species is combined with another species, with the former being so finely divided and mixed that it doesnt rapidly settle out. ... A wire is a single, usually cylindrical, elongated strand of drawn metal. ... Plasma cutting is a process used to cut steel and other metals and any electrically conductive material, using a plasma torch, which uses a powerful electric arc to create plasma out of a blast of ordinary dried air to vaporize or literally plasmatize the medium which is being cut. ...

What are the deposit properties

The deposits consist of a multitude of pancake-like lamellae called 'splats', formed by flattening of the liquid droplets. As the feedstock powders typically have sizes from micrometers to above 100 micrometers, the lamellae have thickness in the micrometer range and lateral dimension from several to hundreds of micrometers. Between these lamellae, there are small voids, such as pores, cracks and regions incomplete bonding. As a result of this unique structure, the deposits have properties significantly different from bulk materials. These are namely mechanical properties, such as lower strength and modulus, higher strain tolerance, and lower thermal and electrical conductivity. Also, due to the rapid solidification, metastable phases can be present in the deposits. Gill may refer to one of the following. ... Strength of materials is the scientific area of applied mechanics for the study of the strength of engineering materials and their mechanical behavior in general (such as stress, deformation, strain and stress-strain relations). ... The modulus of elasticity can also be measured in other units of pressure, for example pounds per square inch (psi). ... In any branch of science dealing with materials and their behaviour, strain is the geometrical expression of deformation caused by the action of stress on a physical body. ... In physics, thermal conductivity, λ or k, is the intensive property of a material which relates its ability to conduct heat. ... Electrical conductivity is a measure of how well a material accommodates the transport of electric charge. ... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ...

What is it good for

This technique is mostly used to produce coatings on structural materials. Such coatings provide protection against high temperatures, corrosion, erosion, wear, change the appearance, electrical or tribological properties of the surface, replace worn material, etc. When sprayed on substrates of various shapes and removed, free-standing parts in the form of plates, tubes, shells, etc. can be produced. It can be also used for powder processing - spheroidization, homogenization, modification of chemistry, etc. In that case, the substrate for deposition is absent and the particles solidify during the flight. Corrosion, atmospheric and biologic (Barnacles) Corrosion is deterioration of useful properties in a material due to reactions with its environment. ... Severe soil erosion in a wheat field near Washington State University, USA. Erosion is the displacement of solids (soil, mud, rock, and other particles) by the agents of wind, water, ice, movement in response to gravity, or living organisms (in the case of bioerosion). ... In materials science, wear is the errosion of material from a solid surface by the action of another solid. ...