Papers by Keyword: Dynamic Hardness

Abstract: The purpose of this investigation is to study the dynamic hardness of MCrAlY abradable coatings under different strain rates. A dynamic indentation device based on the split Hopkinson pressure bar system (SHPB) was used. The results show that the hardness of MCrAlY coating increased with the increase of the strain rate, which has a positive strain rate effect. In addition, the difference of the static hardness of MCrAlY coating prepared by HVOF and LPPS was only 4%, while the difference in dynamic hardness was 16%.

Abstract: The results of experimental studies of a separate contact dynamic interaction of a spherical non-deformable pellet with a plastic flat metal surface at different angles of attack (20° ≤ α ≤ 90°) at high speeds (v ≈ 100m/s) are presented. A method is described for determining the nature of the viscoelastic resistance of a surface layer attacked by a pellet during contact displacement along the normal to the surface and rigid plastic resistance during tangential displacement, which can be used to establish the processing regimes of products by a mass flow of abrasive particles, in particular, shot-blasting cleaning. The results of comparing the obtained and known theoretical data with each other and with experimental studies are presented.

Abstract: The efficiency of applying electrophysical impacts in technological methods of machine part cutting to a great extent depends on the understanding of the processes forming the basis of these impacts. As a rule a specific nature of these processes is characterized by their high intensity, locality of the impact and an impulse mode.The understanding of a certain process is necessary both for its efficient use in technological processes and for the development of new technologies based on the combination with other electrophysical impacts. The paper presents the results of mathematical modeling of deformation processes under ultrasonic frequency impulse plastic impact of a deformer on the surface layer of metals and alloys. Based on the mathematical modeling of the process of ultrasonic deformation of materials, operating parameters of the impact defining the field of application of this method are found. Quantitative relationships between basic characteristics of the deformation process and operating parameters of an ultrasonic impact are established.

Abstract: High-temperature erosion and erosion-corrosion are significant problems for energy conversion systems in power plants. The source is high-temperature dry steam that contains iron oxide and fly ash particles. Compared with high-temperature alloys, ceramic coatings generally have higher resistance to high temperature corrosion and erosion. However, it would be very difficult to obtain mechanical properties for ceramic coating materials in a high temperature environment. With no experimental testing, therefore, the performance of ceramic coatings in an actual plant environment is not typically evaluated before field application. The aim of this paper is to discuss dynamic hardness and fracture toughness as mechanical properties of ceramic coating materials at high temperature, compared with those at room temperature. We chose three types of chromium carbide coating materials that were coated with atmospheric plasma spray (APS), vacuum plasma spray (VPS), and high-velocity oxygen fuel (HVOF) on SUS430 stainless steel.