March 04th, 2021
Plasma spraying is a versatile and cost-effective means of applying high-quality coatings to protect parts and equipment from wear. In this blog post, we are taking a look at the fundamentals of plasma spraying and plasma spray systems.
Plasma spraying is a type of thermal spraying, a group of processes in which cords, rods, suspensions, solutions, powdered materials, or wires are deposited onto a prepared surface in a molten, semi-molten, or softened state to achieve a uniform coating.
Plasma spray systems differ from other thermal spray systems in that the powder feedstock is heated and accelerated by a plasma heat source in the form of a direct current (DC) arc or radio frequency (RF) discharge. Powder feedstock is injected into the plasma, at which point they are heated and accelerated toward the target surface. On striking the surface, these melted or partially-melted particles flatten and solidify into lamellae or “splats”, gradually coating the surface one particle at a time.
Plasma spray systems are capable of achieving temperatures in excess of 8000K at atmospheric pressure, allowing the melting of practically any material. Typically, plasma spray systems are used to spray high added-value coatings. Coatings can be tailored to provide resistance to corrosion, abrasion, erosion, friction, and other sources of stress.
Plasma spray systems were first used for industrial applications around 1960. Since then, plasma spray systems have undergone many developments, enabled by intensive experimentation and modelling.
Around 1970, soft vacuum plasma spraying was introduced in industry, and the ‘80s saw the introduction of robotization. In the ‘90s, improvements in sensor technology enabled the integration of robust sensors to give information on particle temperature, flux, velocity, and other important process parameters. Developments in modelling and the physical theory of plasma-particle interactions led to rapid improvements in plasma spraying technologies, opening up new industrial applications.
Today, powerful integrated plasma spray systems are available, offering high spray rates, high coating quality, and low power consumption.
Plasma spray systems are valued for their versatility and cost-efficiency, earning them common use in manufacturing environments. Plasma spray systems permit coatings with any material provided the melting temperature is at least 300 K lower than the vaporization or decomposition temperature. This means that coatings of high melting point materials can be deposited, enabling plasma spray systems to provide the optimal coating for even the most demanding environments and meet the needs of a wide range of applications.
Saint Gobain produces high-performance plasma spray systems and a complete range of technically superior ceramic feedstock materials. Our products are used throughout the aerospace, automotive, electronics, mining, oil and gas and semiconductor industries. Contact us today if you would like to learn more.