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This study involved the preparation of hydroxyapatite (HAP) nanoparticle coatings on a Ti6Al4V substrate using electrophoretic deposition (EPD) as the coating technique. Their surface morphology, elemental composition, microstructure, crystalline phases, and mechanical performance were investigated before and after heat treatment using scanning electron microscopy (SEM), X-ray diffraction (XRD), and scratch testing. Heat treatment changed the surface morphology and internal structure of the coatings. Scratch test results showed that the heat-treated samples withstood higher critical loads and exhibited stronger adhesion to the substrate. According to the findings, the heat treatment improves the mechanical properties and bonding strengths of the coating while also improving scratch resistance further improving its efficacy for biomedical coating systems.

The study aimed to investigate the impact of varying stand-off distance (SOD) on the weld interface of pure titanium (Ti)/stainless steel (SS316) clads. Microstructural examination revealed a wavy interface morphology of welded clads. The morphological changes of the bonding interface under different SOD conditions showed that both the wavelength and amplitude increased with an increase in the SOD, with the wavelength demonstrating a more pronounced effect. In addition, a scratch test was also employed to characterize the weld interface. It is an important tool for evaluating the mechanical properties of a material. During scratch tests, an oval-shaped scratch morphology was observed on the Ti side, with the appearance of first divergent and then convergent behavior at the weld interface. In the tensile shear test, the Ti/SS316 clads exhibited higher tensile shear strength in the longitudinal direction compared to the transverse direction. The observed tensile shear strength values were in the range of 352.7–404.6 MPa for the longitudinal direction and 295.7–359.3 MPa for the transverse direction. The study found that the tensile shear strength increased in both the longitudinal and transverse directions as the SOD was increased from 5 to 10 mm. However, at an SOD of 15 mm, a decrease in tensile shear strength was observed in both directions. This decrease was attributed to the presence of non-uniform defects, such as cracks, voids, and high plastic deformation, at the interface zone. The fracture study revealed a combination of ductile and brittle fracture, with ductile fracture dominant at lower SOD and brittle fracture at higher SOD. The study found that the SOD had a substantial effect on the output of the weld results, and a SOD of 10 mm was determined to be the optimal welding parameter for Ti/SS316 clads based on microstructure and mechanical properties.

This study investigates the mechanical behavior of various plastic materials through tensile and scratch testing. Three polypropylene-based composites—PP-GB30GF10, PP-TD40, and PP-GF20—were subjected to uniaxial tensile tests in accordance with standard protocols to assess their strength, stiffness, and elongation characteristics. The results highlight notable differences in the tensile performance depending on the type and percentage of reinforcing fillers, such as glass fibers and talc. In parallel, the scratch resistance was evaluated for specimens produced via stereolithography (SLA) using Formlabs Black V4 resin, a common photopolymer used in prototyping applications. The scratch test aimed to characterize the surface durability under localized mechanical stress. The findings contribute to a better understanding of the mechanical performance of these materials and their potential applications in fields requiring both structural integrity and surface resilience, such as automotive components and functional prototyping.

The scientific research in the biomedical sector has underlined the importance of going beyond the basic requirements of the biomaterials, i.e., to be bioinert and avoid the occurrence of any adverse effects once in contact with a biological environment. In fact, the next generation of biomaterials must ensure anti-bacterial and bioactive properties to, for example, accelerate the bone regrowth. Therefore, the activation of a bioinert surface implies an additional step that is generally carried out after the manufacturing process. In the present work, an alternative route is investigated and is based on the mechanical deposition of hydroxyapatite (HA) particles on a Ti- 6 Al- 4 V ELI by applying a compressive load in superplastic conditions. Embedding tests were experimentally carried out using a designed equipment interfaced with a universal Instron testing machine. The applied load and the holding time were changed over three levels according to a full factorial plan and adopting a HA powder with a controlled particles size ranging from 80 to 150 μm. Post-embedding properties were initially analyzed via optical microscopy and further deepened via scanning electron microscopy (SEM). It was demonstrated that high level of the applied load combined with prolonged holding time led to the embedding of an 18 μm uniformly thick layer of HA. The scratch tests proved that embedding in superplastic conditions could ensure a level of adhesion strength comparable to other deposition techniques.

This study concentrates on NiCrAlY-based coating with nano-boron carbide and cenosphere particles. The composition of NiCrAlY, B 4 C and cenosphere are maintained the same for all the samples. The plasma spray technique is used for coating. The erosive wear is carried out for different impingement angles of 30°, 60°, 75° and 90° at 900°C. The morphology of coating before and after erosive wears is studied using scanning electron microscopic analysis. Further, the study is carried out on surface roughness, scratch resistance and coefficient of friction of the eroded surface of the samples. The significant erosive wear resistance is reported for an impact angle of 60° followed by 30°. The surface roughness results reveal the formation of deep craters and the ploughing effect of material on the coatings. The scratch test and COF show the presence of coating and the brittle nature of the failure of the coating.

Passive commercial gauzes were turned into interactive wound dressings by impregnating them with a chitosan suspension. To further improve healing, and cell adhesion and proliferation, chitosan/bioactive glass wound dressings were produced with the addition of (i) 45S5, (ii) a Sr- and Mg-containing bioactive glass, and (iii) a Zn-containing bioactive glass to the chitosan suspension. SEM and FTIR analyses evidenced positive results in terms of incorporation of bioactive glass particles. Bioactivity was investigated by soaking chitosan-based bioactive glass wound dressings in simulated body fluid (SBF). Cell viability, proliferation, and morphology were investigated using NIH 3T3 (mouse embryonic fibroblast) cells by neutral red (NR) uptake and MTT assays. Furthermore, the wound-healing rate was evaluated by means of the scratch test, using NIH 3T3. The results showed that bioactive glass particles enhance cell adhesion and proliferation, and wound healing compared to pure chitosan. Therefore, chitosan-based bioactive glass wound dressings combine the properties of the organic matrix with the specific biological characteristics of bioactive glasses to achieve chitosan composites suitable for healing devices.

Si 3 N 4 ceramic has the advantages of high hardness, high strength, corrosion resistance, and high-temperature resistance and is widely used in aerospace and other fields. As a hard and brittle material, it is prone to problems such as difficult control of processing surface quality and low processing efficiency. In order to explore the influence of the interaction between abrasive grains on the surface processing quality and processing efficiency of Si 3 N 4 ceramic in rotary ultrasonic grinding, the multigrain grinding simulation is carried out to explore the removal mechanism of Si 3 N 4  ceramic material under multigrain coupling. The multi-abrasive scratch test was carried out to verify the simulation. The results show that as the number of abrasive particles increases, the machining forces in both simulations and experiments increase. Meanwhile, the average grinding force per individual abrasive particle decreases. The maximum stress generated by grinding increases first and then decreases as the number of abrasive particles increases. As the number of abrasive particles increases, the depth of surface cracks and the average depth of scratches caused by grinding first decrease and then increase.

The adhesion behavior of inkjet-printed silver nanoparticles (Ag NPs) on various substrates was investigated after furnace sintering at various temperatures. Glass, polyimide, and polyethylene naphthalate substrates were used to examine the effect of the substrate on the adhesion behavior of inkjet-printed Ag NPs. The adhesive forces were estimated using a scratch test. The critical load and shear stress were determined via a microscratch test. The critical shear stress varies according to the adhesion characteristics of each substrate. Cross-sectional images were obtained using a focused ion beam to investigate the morphologies at the boundaries between the sintered ink line and substrates.

Cobalt–chromium–molybdenum (Co-Cr-Mo) alloy is a material recommended for biomedical implants; however, to be suitable for this application, it should have good tribological properties, which are related to grain size. This paper investigates the tribological behaviour of a Co-Cr-Mo alloy produced using investment casting, together with electromagnetic stirring, to reduce its grain size. The samples were subjected to wear and scratch tests in simulated body fluid (Ringer’s lactate solution). Since a reduction in grain size can influence the behaviour of the material, in terms of resistance and tribological response, four samples with different grain sizes were produced for use in our investigation of the behaviour of the alloy, in which we considered the friction coefficient, wear, and scratch resistance. The experiments were performed using a tribometer, with mean values for the friction coefficient, normal load, and tangential force acquired and recorded by the software. Spheres of Ti-6Al-4V and 316L steel were used as counterface materials. In addition, to elucidate the influence of grain size on the mechanical properties of the alloy, observations were conducted via scanning electron microscopy (SEM) with electron backscatter diffraction (EBSD). The results showed changes in the structure, with a reduction in grain size from 5.51 to 0.79 mm. Using both spheres, the best results for the friction coefficient and wear volume corresponded to the sample with the smallest grain size of 0.79 mm. The friction coefficients obtained were 0.37 and 0.45, using the Ti-6Al-4V and 316L spheres, respectively. These results confirm that the best surface finish for Co-Cr-Mo alloy used as a biomedical implant is one with a smaller grain size, since this results in a lower friction coefficient and low wear.

The paper presents the results of scratch tests on the connection of the Al2O3+40%TiO2 coating with the AZ91 alloy casting. The Al2O3+40%TiO2 coating was applied to the AZ91 alloy casting using the APS (Atmospheric Plasma Spraying) method. Microstructure studies and chemical composition analysis of the substrate material and the Al2O3+40%TiO2 coating were conducted. The analysis of the coating to substrate connection was based on microstructure examinations before and after the scratch test. The scratch was made in the direction from the substrate to the coating. In the scratch test, the depth and width of the scratch were determined. Based on the conducted research, it was found that the Al2O3+40%TiO2 coating has a very good quality connection with the AZ91 alloy substrate. The obtained lower values of the geometric parameters of the scratch (width and depth) for the Al2O3+40%TiO2 coating, compared to the AZ91 alloy substrate, indicate the potential use of the Al2O3+40%TiO2 coating to improve the scratch resistance of elements and machine parts made of the AZ91 alloy. The effect of the indenter's intervention during scratching is the degradation of the microstructure of the AZ91 alloy and the Al2O3+40%TiO2 coating. In this process, cracking plays the main role. In the case of the Al2O3+40%TiO2 coating, the effect of the indenter's action is a network of microcracks, while in the microstructure of the AZ91 alloy, cracks appeared in large precipitates of the γ-Mg17(Al, Zn)12 phase.