Influence of Electron Beam Treatment of Co–Cr Alloy on the Growing Mechanism, Surface Topography, and Mechanical Properties of Deposited TiN/TiO2 Coatings

Abstract

This study examines the effect of electron beam treatment (EBT) of Co-Cr substrate on the film growth mechanism, mechanical properties, and surface topography of TiN/TiO 2 coatings deposited by reactive magnetron sputtering. The obtained results and processes that occurred during the deposition are discussed in the context of crystallographic principles, and special attention is paid to the crystallographic orientation and growth mechanism studied by X-ray diffraction (XRD). The mechanical properties were investigated by means of nanoindentation and wear tests. The surface topography was evaluated using atomic force microscopy (AFM). The results obtained in the present study showed that polycrystalline TiN and anatase TiO 2 phases were present in all cases. Electron beam treatment of Co-Cr substrate tended to form a reorientation of the microvolumes from (111) to (200) of TiN, leading to a change in the growth mechanism from three-dimensional (Volmer-Weber) to layer-by-layer (Frank-van der Merwe). It was found that the electron beam treatment process did not significantly affect the thickness of the coatings and the deposition rate. The treatment process led to an increase in surface roughness. The higher surface roughness after the EBT process should be appropriate to support cell growth and adhesion on the surface of the deposited bilayer coating. It was demonstrated that EBT of the substrate caused a decrease in hardness of the deposited coatings from 10 to 5 GPa. The observed decrease in hardness was attributed to the change in the preferred crystallographic orientation and film growth mechanism. The hardness of the bilayer coating after the application of EBT of the Co-Cr substrate was much closer to that of human bones, which means that severe stress shielding effect could not be expected. The evaluated coefficient of friction (COF) exhibited significantly lower values in the case of EBT of the substrate compared to the untreated Co-Cr material.resistance, which depends mostly on the surface properties and can be overcome by appropriate surface modification technologies [4].During the last decades, considerable attention has been paid to surface manufacturing of materials by high-energy fluxes (HEFs) (i.e., electron and laser beams). In these technologies, the electrons or photon fluxes interact with the surface of the sample, heat the treated area, and form a thermal distribution. The rate of heating and cooling can be characterized by quite high values (about 10 5 -10 6 K/s), which lead to some structural changes in the functional properties [5][6][7][8][9][10]. The authors of [11] demonstrated an innovative approach for controlling the surface topography and tribological behavior of biomedical alloys, such as Ti6Al4V, by means of electron beam surface treatment. Other researchers [12,13] have successfully demonstrated the possibilities for enhancing the wear and corrosion properties of steel by the formation of carbon fiber-reinforced Ni-based composite coatings via laser cladding. Laser beam technologie...

Electron-Beam Surface Treatment of Metals and Alloys: Techniques and Trends

“…Furthermore, the obtained values for the hardness after the EBT of the substrate are closer to that of the human bones and the severe stress-shielding effect after implants insertion into the body could not be expected. Similar work was carried out by Valkov et al [45]. The authors studied the effect of electron-beam treatment of Co-Cr alloy on the growing mechanism, surface topography and mechanical properties of bilayer TiN/TiO2 coating.…”

“…In addition, the treatment process led to an increase in the surface roughness, about 3 times and a decrease in the hardness from 10 GPa to 5 GPa. The aforementioned works [44,45] demonstrated an interesting approach for controlling the surface properties of biomedical materials. The problem related to an increase in the contact area and cell-adhesion support was solved by increasing the surface roughness.…”

Improving the Properties of Laser-Welded Al–Zn–Mg–Cu Alloy Joints by Aging and Double-Sided Ultrasonic Impact Compound Treatment

“…To improve the comprehensive properties of 7075 aluminum alloy joints, post-weld treatment is an ideal and popular method [ 12 , 13 , 14 ]. Many post-weld treatment methods exist for welded joints, such as electron beam treatment [ 15 , 16 ], heat treatment and mechanical treatment. However, welded joints of 7075 aluminum alloy normally undergo post-weld heat and mechanical treatments, of which the heat treatment is usually aging treatment [ 17 , 18 ], and the mechanical treatment usually ultrasonic impact treatment (UIT) [ 19 , 20 ].…”

Formation Mechanism of Micro- and Nanocrystalline Surface Layers in Titanium and Aluminum Alloys in Electron Beam Irradiation

“…Micro-, submicro-and nanocrystalline structures with a high level of hardness and wear resistance meet these requirements [3]. To form these layers concentrated energy flows are applied i.e., the heterogeneous plasma flow processing in conjunction with the succeeding low energy high current electron beam irradiation [4][5][6]. The latest research in this field [7,8] has highlighted microand nanocrystalline layers with a columnar structure ( Figure 1) form when irradiating titanium and silumin processed prior by the electric explosion plasma of yttrium powder.…”