Development and Studying of the Technology for Thermal Spraying of Coatings Made from Ultra-High-Molecular-Weight Polyethylene

Abstract

UHMWPE is resistant to acids, alkalis and radiation. Its combination of unique properties makes this material attractive for obtaining multifunctional coatings. However, in practice, obtaining coatings based on UHMWPE is associated with difficulties associated with low thermal conductivity and high viscosity of the material. The possibility of overcoming the technological problems of obtaining gas-thermal coatings based on UHMWPE was studied in the present work. A physical model of a flame with UHMWPE particles moving along the central axis was developed by the finite element method. The temperature along the central axis of the plume was determined. The interaction between a gas-thermal torch and a UHMWPE particle was established. It was determined that the residence time of UHMWPE particles in a gas-thermal flame is not enough for its complete penetration, which is the reason for the appearance of various defects. The interrelation of the particle heating rate in the torch depending on its diameter was determined. A new variant of coating deposition with preliminary heating of the powder in a fluidized bed was proposed. The thermal characteristics of UHMWPE powder were determined by differential scanning calorimetry and thermogravimetric analysis. The allowable temperature interval for UHMWPE deposition was established. Coatings were obtained under various deposition modes. It was established using the methods of X-ray diffraction analysis and infrared spectroscopy that the structure of the crystal lattice of UHMWPE did not change after deposition. Significant oxidation processes do not occur during spraying. It was found using scanning electron microscopy that the coatings obtained with preliminary heating of the powder in a fluidized bed do not have air inclusions. The obtained results make it possible to obtain higher quality coatings.