AP13068529 "Development of technology for electron-beam modification of polymeric materials used in mechanical engineering"

Supervisor: Mukhametov Nurzhan Yerbolovich, PhD, - Project Manager ORCID ID - 0000-0002-6672-180x

Relevance:

High performance polymeric materials such as PEEK and PTFE are considered as a potential tribological material for reciprocating mechanical systems due to their self-lubricating properties, especially under conditions of high loads and sliding speeds. PEEK and PTFE have a number of exceptional properties such as exceptional thermal stability, excellent mechanical properties, and high wear resistance. Therefore, these remarkable characteristics make them potentially superior wear material candidates compared to other types of polymers. However, pure PEEK and PTFE generally exhibit poor wear resistance, which limits their use in friction applications. Therefore, PEEK and PTFE must be modified to increase service life through reinforcement technology or surface modification during the actual application. One of the promising ways to modify the surface of polymeric materials is electron beam processing, which has great potential.

Target:

Development of a technology for electron-beam modification of polymeric materials, which makes it possible to increase their wear resistance, as well as the study of the regularities of structural and radiation-chemical transformations in the surface layers of PEEK and PTFE during non-vacuum electron beam processing.

Expectation:

1. The structure, chemical composition, physicochemical characteristics, physico-mechanical and tribological properties of polymeric materials will be investigated depending on the mode of electron irradiation.
2. Optimum modes of non-vacuum electron-beam processing of polymeric materials will be determined, providing high wear resistance of the surface layer.
3. Regularities will be established for the formation of the structure and properties of the modified surface layer of polymeric materials during electron beam processing.
4. Bench testing of parts made of polymer materials treated with an electron beam will be carried out.
5. On the basis of the data obtained, innovative proposals will be formulated with the prospect of introducing the developed radiation technology into production.

Result:

Rus: Electron beam processing of polymer samples was carried out on a linear source ILU-10. The effect of several parameters of electron irradiation on the modification of the surface of PEEK and PTFE polymers was studied. Samples of these polymers were irradiated at beam energies of 2.7, 3.2, 3.7, 4.2, 4.7 MeV and at irradiation doses of 400, 600 kGy for each beam energy value. The current and irradiation rate were the same for all samples. Hardness and elasticity measurements of the samples after irradiation were performed on a FISCHERSCOPE HM2000S hardness tester in accordance with DIN EN ISO 14577-1 and ASTM E 2546. The sample holding time under a load of 1000 mN for PTFE and PEEK polymers was 20 s. The wear test of polymer samples in dry friction mode was carried out at the Research Center of Surface Engineering and Tribology using the ball-on-disk scheme at a load of P = 9 N and a sliding speed of V = 0.04 m/s on an Anton Paar 𝑇𝑅𝐵3 tribometer in accordance with the international standards ASTM G99-959, DIN50324 and ISO 20808. A counterbody in the form of a ball made of ШХ15 steel was used in tribological tests. The counterbody diameter was 6 mm. The test path was 1000 and 2000 m. To determine the surface roughness of polymers before and after electron beam processing, contact profilometers of model 130 and HY2300 were used. Also, volumetric wear was estimated by the friction track profile using the above-mentioned profilometers. In addition, thermogravimetric analysis of polymer samples was performed on a TGA 1250 analyzer. Each sample, initially ground to powder, was heated in the range of 500-800 degrees Celsius. The results of this study showed that the best mechanical properties for PTFE polymer can be obtained with the following irradiation parameters: electron energy - 3.2 MeV, current - 6.84 mA, speed - 5 m/min, irradiation dose - 600 kGy and 5 irradiation runs. Under these conditions, the hardness value was equal to 41.9 MPa and roughness 2.61 μm. For PEEK polymer samples, the best results were obtained with the following parameters: electron energy - 3.7 MeV, current - 6.84 mA, speed 0.3 m/min and 5 runs. The sample hardness increased to 201.9 MPa and the roughness value was equal to 0.74 μm. The results showed that significant changes in the microhardness of the polymers were observed after electron beam treatment. A study of the volumetric wear of polymers under electron beam exposure showed a decrease in the wear rate and a decrease in the friction coefficient in relation to the original polymer. To solve the problem of heat flux distribution over the depth of the polymer sample, equations for a pulsed electron flow source were used. The solution of this equation requires determining the following values:

  • Power of electron beam exposure – P [W].
  • Speed of part processing – V [m/s].
  • Time of exposure in the irradiation zone – t [s].
Data on the dimensions of the part –d Х l (diameter and height of the sample), Depth of electron penetration into the sample, depth of maximum energy release – h = 0.75 ⋅ S [m]. To find the depth of electron penetration, a numerical calculation was performed using the MathCad mathematical environment for the Bethe equation, taking into account the electron slowdown. A fractographic analysis of wear grooves was performed. Studies were conducted to clarify the mechanisms of structural changes in reinforced PEEK and PTFE polymers during abrasive and impact-abrasive wear. Images of wear tracks of PEEK and PTFE polymers were obtained before and after their irradiation with an electron beam on an Anytester HY2300 contact profilometer. The relative wear resistance of the samples was determined based on the measured mass loss. Microscopic images of wear tracks were taken to visualize changes on the surface of the samples after testing. The results of the fractographic analysis indicate that electron irradiation leads to modification of the surface layers of polymers, changing their structural characteristics and properties. As a result, the irradiated PEEK and PTFE samples showed improved resistance to abrasive wear compared to the original samples. This is confirmed by a decrease in the depth and width of wear grooves, indicating an increase in the wear resistance of PEEK and PTFE polymers after irradiation. Work is underway to establish the main patterns of formation of the fine substructure of PEEK and PTFE samples under electron irradiation. The main attention is paid to the analysis of changes in the fine substructure caused by electron beam treatment in order to understand the mechanisms and consequences of such an impact on the materials. Exposure to an electron beam led to changes in the internal bonds of polymers, affecting their physical and mechanical properties. The changes affected the formation of new crystalline and amorphous structures, which improved the resistance of materials to external influences or, in some cases, increased their susceptibility to certain types of deformation. Using the FT-801 spectrometer, spectra were obtained in the range from 4000 to 500 cm^-1. Each measurement provided data on the presence and change of functional groups in the polymer structure with a measurement accuracy ranging from ±1% to ±3%, which guarantees high reliability of the results. XRD analysis, carried out using an X’Pert PRO diffractometer, allowed us to evaluate changes in the crystalline structure of the polymers. The study was carried out in the 2θ angle range from 10 to 40° using CuKα radiation. The obtained XRD analysis results confirmed the microstructural changes associated with irradiation, which contributes to a deeper understanding of the effect of electron irradiation on the studied materials.


2023

  • Ormanbekov, K. D., Rakhadilov, B. K., Zhassulan, A. Z., Mukhamedov, N. E., Shynarbek, A. B., & Magazov, N. M. (2023). Effect of electron irradiation on mechanical, tribological and thermal properties of polytetrafluoroethylene. Eurasian Journal of Physics and Functional Materials, 7(4), 221-231. https://doi.org/10.32523/ejpfm.2023070402
  • Орманбеков К.Д., Рахадилов Б.К., Кусаинов Р.К., Абильмажинов Е.Т. «Воздействие электронного облучения на механико-трибологические свойства полиэфиримида» Труды Университета. Серия «Машиностроение. Металлургия», №3,2023. – С.89-95. https://doi.org/10.52209/1609-1825_2023389
2024


  • Rakhadilov, B., Ormanbekov, K., Zhassulan, A., Mukhamedov, N., Mukhametov, Y., & Kussainov, R. (2024). Study of structural, surface energies, and tribomechanical properties of thermoplastics irradiated by electron beam. Materials Research Express. https://doi.org/10.1088/2053-1591/ad6a02

Study Team Members

  • Fullname: Рахадилов Бауыржан Қорабайұлы, PhD

    Scopus Id: 55539741700

    Researcher Id: ---

    ORCID: 0000-0001-5990-7123

    Additionally: