Modification of the Surface of Refractory Materials by Cold Gas-Dynamic Spraying

Refractory bricks are used worldwide in thermal setups such as coke ovens, blast furnaces and power plants because they can work at high process temperatures. Undesirable processes of erosion, wear, crack formation and failure of the refractory materials take place particularly upon the thermal setups operation, in which the working surfaces of ovens are subjected to strong thermo-mechanical stresses. Prolonging the life of refractory elements will give a significant economic effect for every production process. This can be achieved by a modification of surfaces of refractory materials by means of cold spray process. In the cold spraying method, fine solid particles are dispersed in a gas stream, accelerated by a Laval nozzle to supersonic velocities (500–1200 m/s) and deposited on the substrate surface by impact forming a strong bonding. In this work, bonding mechanisms of the fine particles cold sprayed on the porous surface of refractory materials and the formation mechanisms of the protection layer are studied experimentally and by numerical simulations. The surface properties, such as the porosity, roughness, hardness are analyzed using SEM, confocal microscopy and nanoindentation, respectively. The bonding strength of deposited particles is characterized with ultrasonic tests.