No 2 (2025)
Статьи
ELECTRON MICROSCOPIC STUDY OF THE CONTACT ZONE SURFACE (HIGH-SPEED STEEL P2M9) ‒ SUBSTRATE (STEEL 30KHGSA)
Abstract
One of the important problems of practical application of high-strength plasma surfacing of high-speed steels in a nitrogen environment is the analysis of the damping properties and adhesion of the surfacing and the substrate, since these properties largely determine the premature nucleation of brittle microcracks in the contact zone. Such results can be obtained only using highly informative methods of modern materials science, such as scanning and transmission electron microscopy. In the article, surfacing of tungsten-molybdenum steel P2M9 has recently found wide application instead of well-known tungsten (type P18, P9) and tungsten-molybdenum steels with increased tungsten content (type P6M5, P6F2K8M6, etc.). This is due to the need to replace expensive and scarce tungsten with molybdenum, which, being in the same group of the Periodic Table of Elements with W, has a similar effect on the structure and properties of high-speed steels. The structural-phase states, morphology and elemental composition of the transition zone of the contact of the system "deposited high-speed steel R2M9-substrate (steel 30KhGSA)" in the initial state and after triple high-temperature tempering were studied. In the initial state, the transition zone has a martensitic structure with layers of residual austenite along the boundaries of martensite plates. Particles of the second phase of the nanosized (2 ‒ 60 nm) range were revealed – vanadium, molybdenum, tungsten and iron carbides localized at dislocations, at the boundaries and in the volume of martensite plates. Triple high-temperature tempering does not change the morphology of the carbide phase particles of the transition zone. Possible physical causes of the observed patterns are discussed.
PLASMA MODIFICATION OF THE SURFACE OF POLYPROPYLENE FILMS AT ATMOSPHERIC PRESSURE
Abstract
Polymer self-adhesive materials are widely used in various industries (construction, medicine, packaging, automotive, advertising, electronics and consumer goods). Their popularity is due to their operational characteristics: resistance to external influences and ease of use. The results of studies of the surface properties of polypropylene (PP) films modified using low-temperature plasma of atmospheric pressure glow discharge are presented. The treatment time was 3, 5, 10, and 15 seconds, and the plasma was initiated in technical argon, air, and mixtures thereof in the proportions of 70:30, 50:50, and 30:70. The study shows that the plasma modification significantly improves the adhesive properties of polypropylene, doubling them compared to the original sample. The maximum adhesion performance (135.5 MJ/m2) of PP was achieved with modification in argon for 15 seconds, which doubled the adhesion properties compared to the initial sample. An increase in the processing time of more than 15 seconds does not affect the adhesive properties and the wetting edge angle. A mixture of argon and air was used to reduce argon consumption. The optimal 50:50 ratio ensured an edge wetting angle of 42 ± 1° and an adhesion of 127.9 MJ/m2 (close to the values of pure argon). An increase in the surface roughness of modified PP films was noted from 52.6 to 199.4 nm in argon, to 133.1 nm in an argon‒air mixture (50:50). Increasing the roughness facilitates the application of glue and strengthens the adhesive bond. The study investigated the kinetics of changes in the electret properties of PP films and their effect on adhesive properties. The results obtained during the study are recommended for the development of basic materials for self-adhesive products with improved performance properties.