In 1984, the discovery of icosahedral quasicrystals challenged established scientific theories in the field of creating new materials. Quasicrystals are highly ordered solid phases whose properties are fundamentally different from those of ordinary crystals, glasses and other known materials. The extraordinary characteristics of quasicrystals, including their high mechanical strength, are due to the absence of periodicity in their structure, which slows down the propagation of dislocations, unlike crystalline substances. Due to the unique combination of physical properties, quasicrystals are considered promising materials for the aerospace, rocket, instrument-making and energy industries. Their use in the form of nano-objects, such as coatings, ultrafine fillers for composite materials and ultrafine modifiers, is considered especially promising.
The production of quasicrystals and quasicrystalline phases usually requires high rates of transition from a liquid or gaseous state to a solid, with the cooling rate during solidification being in the range of 104…106 Gy/s. The plasma spraying method is considered one of the most promising approaches to the manufacture of products from quasicrystalline materials.
The Vulcan laboratory has developed a semi-automatic unit for applying quasi-crystalline coatings using a plasma torch that provides the necessary spraying parameters, such as temperature and particle speed, plasma jet, spray spot movement, plasma torch movement, part surface movement, and coating temperature. The spraying parameters are determined by the plasma torch design, cooling system, chamber atmosphere, and depend on the power supplied to the plasma torch, plasma-forming and transporting gas flow rate, and powder flow rate. Stability, monitoring, and control are provided by the corresponding control and monitoring systems. The unit has produced quasi-crystalline coatings with a controlled phase ratio and improved properties.
The Saunin plasma torch is installed at a distance of 120 mm from the complex-shaped part. The part is cooled with water. The powder used is Al65Cu22Fe13, which is fed into the plasma torch, heated in a plasma jet with a power of 12 kW and transferred to the part at a speed of 150 m/s. The powder utilization rate is 80%. The temperature in the spray spot is determined by the speed of movement of the plasma torch and the part.
Author: V. N. Saunin, S. V. Telegin, V. P. Kovalkova
Institute: Siberian State Aerospace University named after Academician M. F. Reshetnev