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Thermal spray coating technology has been widely used throughout Europe and gradually proves its superiority in many projects. In addition to providing corrosion protection and performance enhancement, the metal coating is also used to repair and restore corroded or misc-machined parts. So how exactly is this method done? What makes this coating so outstanding? We will answer all in the article below.
Thermal Spray Coating technology is increasingly interesting based on the benefits and efficiency. With the development of techniques and technology, metal coating methods have also been improved in many aspects to bring better efficiency. So let’s learn about coating characteristics, practical applications, and the advantages/disadvantages of this advanced technology through the sections presented below.
The metal coating is a technological method used to restore and regenerate layers of metal/non-metallic materials, the surface of material parts. The mechanism of this method is to partially or wholly heat solid materials in the form of powders, wires, bars, or drug cores utilizing a high-energy matter stream (gas or plasma flow). The material is dispersed into particles in a fine mist and accelerated to push the particles to the prepared surface to be coated.
All thermal spray methods involve the release of treated material particles onto the cleaned part to be coated. The coating material adheres to the surface and forms a continuous coating. With such forming characteristics, the coating will have a layered structure. In it, the material elements are deformed and stacked on top of each other. There are stable bonding processes that create the coating structure at the contact surface between the details and the part and the contact surface of the elements.
Thermal spray coating materials can be metal, steel, alloy, ceramic, plastic, and composite materials. Metal coating technology provides coatings with thicknesses ranging from approximately 20 micrometers to several millimeters, depending on the process and materials. And can be applied in a variety of thicknesses, typically 100 – 750 microns. Coating quality is usually assessed by measuring porosity, oxide content, macro and micro-hardness, bond strength, and surface roughness.
Thermal spraying has the versatility application, creating coatings for various materials and components to resist abrasion, corrosion, and cavitation. In addition, the coating spray process is also used to provide conductivity or electrical insulation, lubrication, high or low friction, sacrificial wear, chemical resistance, and other desirable surface properties.
Metal coating is used in many different industries with valuable applications. These coatings are solid materials consisting of metals or alloys (in the form of wires, rods, or powders) that are heated and melted in contact with fuel combustion in the injector. The flame from the atomizer will power the heated mixture. As a result, the mixture is sprayed onto the metal surface and creates a solid coating with good adhesion. Here are the four most popular methods today to create a thermal spray coating:
Flammable gas flame spraying is considered an effective method of metal coating spraying and has been widely applied in various industries for the past 100 years. Flame spraying is also divided into two popular types: wire spraying and powder spraying. The flame injection process uses an oxy-acetylene flame. The heat from the flame melts the coating material, and the compressed air pushes it onto the material’s surface to be coated. This process is also another form of “cold process” due to the relatively low operating temperatures throughout the process.
The electric arc spray method is widely used due to its cost-effectiveness and time-saving construction. This method forms an arc by contracting two oppositely charged metal wires, usually of the same composition. This leads to melting at the tip of the wire material. The air atomizes the molten spray material and accelerates to the surface. We can adjust the injection speed by changing the wire feed when heating it. The arc spray coating provides high bond strength, low surface temperature, and high coverage rate, making it suitable for large areas of coating material. Typical applications for this method include anti-wear, anti-corrosion, component repair, and anti-fraying. This system has high mobility, so it is very suitable for large structures or intricate details on-site and local processing applications.
HVOF (High-velocity oxygen fuel) is a metal coating process applied to material surfaces that need thick and high adhesion. The mechanism of the HVOF process is to push the material powder in a semi-molten form at supersonic speed to the surface of the material to be coated. Fuel (hydrogen/kerosene) is mixed with oxygen and ignited in the combustion chamber, and the combustion gas is accelerated in the injection chamber through the nozzle. This creates a significant acceleration which increases the speed of the particles in the mixture. The result is a fragile coating evenly distributed over the surface with a high mechanical bond to the surface components, with good adhesion.
The plasma coating process involves spraying a molten or semi-molten powder onto the surface of a material to create a coating. The coating material is injected in powder form into a high-temperature plasma flame. Under the heating agent and carrier gas, the material is rapidly pushed onto the surface of the device to be coated. The coatings produced by plasma spraying can be a few micrometers to several millimeters thick. Plasma sprayed coatings typically use higher temperatures and lower velocities (compared to HVOF), allowing them to be applied to a wide variety of coated surfaces, including ceramics.
Metal coating can be used in many practical applications, including protecting aircraft, buildings, and other structures from extreme temperatures, chemicals, or environmental conditions such as high humidity and rain. Some popular applications include:
Insulation coatings are also known to be a perfect solution to corrosion problems under insulation. Learn more about metal coatings to reduce insulation corrosion effectively in this article Application of metal coating method to reduce corrosion in insulation.
However, as a highly appreciated and widely applied technology solution, thermal spraying is not always the best solution for projects. So, let’s look at the pros and cons of metal coating to determine its suitability for your plan in terms of efficiency and implementation costs.
Besides the above advantages, the thermal spray method still has some disadvantages that need to be overcome:
Despite some limitations, metal coating technology is still considered a corrosion protection method that shows great promise in the future. Not only does it provide a long-lasting solution, but it has also proven effective in protecting surfaces over the years. Advances in thermal spray equipment have dramatically increased injection rates since the technique has become widely used, significantly cutting down on the time it takes to complete projects.
If you want to find an effective, economical, and limited solution to the above disadvantages, VIVABLAST’s professional technicians will directly evaluate and apply the appropriate metal coating method for your projects. Surface preparation and coating processes are carried out according to standard procedures, using advanced spray-painting technologies to provide the ultimate anti-corrosion solution for your property.
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