Ti6Al4V alloy was shot peened by using stainless-steel shots with different sizes (0.09–0.14 mm (S10) and 0.7–1.0 mm (S60)) for two durations (5 and 15 min) using a custom-designed peening system. ...The shot size was the main parameter modifying the roughness (0.74 µm for S10 vs. 2.27 µm for S60), whereas a higher peening time slightly increased roughness. Hardness improved up to approximately 35% by peening with large shots, while peening time was insignificant in hardness improvement. However, longer peening duration with large shots led to an unwanted formation of micro-cracks and delamination on the peened surfaces. After dry sliding wear tests, the mass loss of peened samples (S60 for 15 min) was 25% higher than that of un-peened samples, while the coefficient of friction decreased by 12%. Plastically deformed regions and micro-scratches were observed on the worn surfaces, which corresponds to mostly adhesive and abrasive wear mechanisms. The present study sheds light on how surface, subsurface and tribological properties of Ti6Al4V vary with shot peening and peening parameters, which paves the way for the understanding of the mechanical, surface, and tribological behavior of shot peened Ti6Al4V used in both aerospace and biomedical applications.
AA1050 Al alloy samples were shot-peened using stainless-steel shots at shot peening (SP) pressures of 0.1 and 0.5 MPa and surface cover rates of 100% and 1000% using a custom-designed SP system. The ...hardness of shot-peened samples was around twice that of unpeened samples. Hardness increased with peening pressure, whereas the higher cover rate did not lead to hardness improvement. Micro-crack formation and embedment of shots occurred by SP, while average surface roughness increased up to 9 µm at the higher peening pressure and cover rate, indicating surface deterioration. The areal coverage of the embedded shots ranged from 1% to 5% depending on the peening parameters, and the number and the mean size of the embedded shots increased at the higher SP pressure and cover rate. As evidenced and discussed through the surface and cross-sectional SEM images, the main deformation mechanisms during SP were schematically described as crater formation, folding, micro-crack formation, and material removal. Overall, shot-peened samples demonstrated improved mechanical properties, whereas sample surface integrity only deteriorated notably during SP at the higher pressure, suggesting that selecting optimal peening parameters is key to the safe use of SP. The implemented methodology can be used to modify similar soft alloys within confined compromises in surface features.
We performed tomographic investigation of the most heavily perturbed (thus highly radioactive) rod and its pristine/unirradiated replicate from the target No. 12 of the Swiss neutron spallation ...source (SINQ). The tomographic dataset reveals the 3D re-distribution of the lead filling inside the irradiated Zircaloy tube. The change in the linear attenuation coefficient of both the lead filling and the Zircaloy tube of the irradiated rod (due to the presence of the entrapped spallation products) in comparison with the pristine/unirradiated material is quantified. The dataset provides valuable input for the enhancement of safety and efficiency of future spallation targets at SINQ.
The present study aims to examine the effects of operational parameters on the surface topography and wear mechanisms of monolithic and conventional yttria‐stabilized zirconia (Y‐TZP) ceramics in the ...micro blasting process, performed under various acceleration pressures (1.5–3 bar), particle impact angles (30°–90°), and erodent particle sizes (50–460 μm). Three‐dimensional (3D) surface topography, surface roughness, and surface morphology of micro‐blasted specimens were analyzed by using non‐contact optical profilometry and SEM‐EDS. The micro blasting characteristics of both Y‐TZP were similar that increased blasting pressure and erodent particle size increased surface roughness. Erosion rate increased with increasing blasting pressure, whereas it decreased with increasing erodent particle size. Particle size was the most effective parameter on changing surface topography, while the particle impact angle had no distinct effect on the erosion rate, surface roughness, and surface topography of Y‐TZP ceramics. SEM‐EDS analyses showed that the primary wear mechanism during micro blasting was micro‐cutting with a substantial amount of embedded particles on the material's surface.
The present study aims to: (1) examine the effects of operational parameters on the surface topography of yttria‐stabilized zirconia (Y‐TZP) ceramics in micro blasting process, and to (2) investigate wear and deformation mechanisms affecting surface topography during roughening of monolithic and conventional Y‐TZP ceramics via micro blasting process, which was performed under various acceleration pressures (1.5–3 bar), particle impact angles (30°–90°), and erodent particle sizes (50 –460 μm) via a micro blasting test rig. The micro blasting characteristics of both Y‐TZP were similar that increased blasting pressure and erodent particle size lead to increase in surface roughness, and erosion rate rises with increasing blasting pressure, whereas it decreases with increasing erodent particle size. Particle size is the most effective parameter on changing surface topography while particle impact angle had no distinct effect on the erosion rate, surface roughness, and surface topography of Y‐TZP ceramics.
The present study aims to reveal the effectiveness of grit blasting when modifying the surface properties of a Ti6Al4V alloy deteriorated due to shot peening. Ti6Al4V samples shot-peened under ...different parameters were grit-blasted (at impingement angles of 30° and 90°, blasting pressures of 1.5 bar and 3 bar). Grit blasting proved to be an effective way of tailoring the surface topography as the surface roughness of shot-peened samples (approx. 10 µm) declined to approx. 2 µm. The surface modifications mainly occurred via micro-ploughing and micro-cutting wear mechanisms, indicating that grit blasting at 30° was more favourable than at 90° for modifying the deteriorated surface properties after shot peening. Shot-peened samples behaved similarly to mirror-polished unpeened samples during grit blasting, showing that the modified surface and subsurface properties obtained via shot peening have an insignificant effect on grit blasting of the alloy. A quantitative analysis of the area covering the embedded particles on the surface of the alloy due to grit blasting showed that the area almost doubled when the alloy was grit blasted at 90° compared to 30°, highlighting an excessive amount of embedding, which would be critical when surface decontamination is important.
Titanium alloys have been used in biomedical and aerospace applications owing to their excellent biocompatibility, high strength/weight ratio, and high corrosion resistance. The reactivity of contact ...surfaces of titanium alloys can be improved by roughening up the surface via grit blasting, which significantly improves the biocompatibility and the adhesion strength between substrate and coating for coating applications. This study investigates the effects of grit blasting parameters (grit size and blasting pressure) on the 3D surface topography, areal surface roughness, and surface morphologies of Ti6Al4V alloy. Ti6Al4V alloy specimens were blasted by various size garnet particles (20/40 and 180 mesh) under different blasting pressures (1.5, 3, and 4 bar) at constant particle impingement angle (90°). 3D optical microscope analyses and scanning electron microscopy analyses were carried out to determine the areal surface roughness, 3D surface topographies, and morphologies of the grit blasted specimens. The increases in particle size and blasting pressure increased the surface roughness of the specimens. The 3D surface topographies of grit blasted specimens were visualized and discussed. The 3D surface topographies and morphologies of the specimens were varied depending on both parameters. Finally, particle embedment was determined due to the grit blasting and detected via EDS analysis.
Grit blasting has been used to tailor the surface properties of specifically biomaterials for the last decades. It utilizes repeatedly impacts of erodent particles to tailor the surface roughness of ...biomaterials for improving their biocompatibility and adhesion strength. Titanium alloys, specifically Ti6Al4V alloy, have been prevalently used as biomaterials and are generally subjected to grit blasting to improve surface properties. In this study, the effects of particle impingement angle, which is widely reported as an important operation parameter in grit blasting, on the 3D surface topography and areal surface roughness of titanium alloys have been investigated in detail. Ti6Al4V alloy specimens were grit blasted by garnet particles (20-40 mesh) under constant particle blasting pressure (1.5 bar) at various particle impingement angles (15°, 30°, 45°, 60°, 75°, and 90°). The surface properties of grit blasted Ti6Al4V alloy; the areal surface roughness values and the 3D surface topographies were obtained by a 3D optical microscope and scanning electron microscopy analyses were also carried out to investigate the surface morphologies. The results show that particle impingement angle significantly affected the surface properties of Ti6Al4V alloy, the areal surface roughness values and the surface morphologies dramatically varied depending on the impingement angle.
Neutron imaging has gained significant importance as a material characterisation technique and is particularly useful to visualise hydrogenous materials in objects opaque to other radiations. ...Particular fields of application include investigations of hydrogen in metals as well as metal corrosion, thanks to the fact that neutrons can penetrate metals better than e.g. X-rays and are at the same time highly sensitive to hydrogen. However at interfaces for example those that are prone to corrosion, refraction effects sometimes obscure the attenuation image, which is used to for hydrogen quantification. Refraction, as a differential phase effect, diverts the neutron beam away from the interface in the image which leads to intensity gain and intensity loss regions, which are superimposed to the attenuation image, thus obscuring the interface region and hindering quantitative analyses of e.g. hydrogen content in the vicinity of the interface or in an oxide layer. For corresponding effects in X-ray imaging, a phase filter approach was developed and is generally based on transport-of-intensity considerations. Here, we compare such an approach, that has been adapted to neutrons, with another simulation-based assessment using the ray-tracing software McStas. The latter appears superior and promising for future extensions which enable fitting forward models via simulations in order to separate phase and attenuation effects and thus pave the way for overcoming quantitative limitations at refracting interfaces.
PDF
