1,721,000 research outputs found
Electropolishing in ecofriendly solution of Ti6Al4V parts produced by electron beam melting
No full textThe additive manufacturing process is gaining increasing interest due to the possibility of producing components with a complex shape, very close to the final geometry. On the other hand, however, it involves a very high final roughness, such as to compromise the mechanical performance and resistance to corrosion. Therefore, post-processing treatments are required. Electropolishing could be the ideal treatment to reduce the roughness of these components. It is known that various parameters, such as the type of electrolyte solution, the voltage or current applied, the treatment time, agitation, etc. They could affect the effectiveness of the electropolishing treatment. The most used electrolyte solutions are dangerous to handle and difficult and expensive to dispose of. The aim of this work was to study a possible electropolishing treatment on Ti6Al4V samples made by Electron Beam Melting (EBM) using an “eco-friendly” electrolytic solution
Systematic study of preparation technology, microstructure characteristics and mechanical behaviors for SiC particle-reinforced metal matrix composites
Full text linkThis article provides a review of the research progress on SiC particle-reinforced metal matrix composites (MMCs), which are a novel type of structural material known for their high strength, hardness, and thermal stability. The potential applications of these composites in aerospace, automobiles, electronics, and specialized mechanical equipment are discussed. The article covers the preparation technology, microstructure, mechanical properties, wear resistance, and application of SiC particle-reinforced MMCs. The advantages, disadvantages, and applicability of different methods are compared. Furthermore, this study explores the relationship between the mechanical properties and microstructure of SiC particle-reinforced MMCs. It also examines the influence of interfacial reactions on the macroscopic properties of these materials. Finally, this article summarizes the application of SiC particle-reinforced MMCs in aerospace, automotive, electronics, and other industries. It also discusses the possible future development directions of these materials. These research results serve as a valuable reference for future research and application of SiC particle-reinforced MMCs. Furthermore, they contribute to the advancement of MMC research and development by offering innovative design concepts and research methodologies to create high-quality structural composite materials. Additionally, this research may inspire the proposal of new manufacturing methods to produce composites with enhanced overall performance in the future
As-Built EBM and DMLS Ti-6Al-4V Parts: Topography–Corrosion Resistance Relationship in a Simulated Body Fluid
No full textMachined devices made of titanium or titanium alloys are widely used in biomedical applications. Recently, additive manufacturing technologies (AM) were proposed to reduce the cost of parts and customise their shape. While several researchers have studied the characterisation of the machined surfaces of AM products, less attention has been focused on the study of the surfaces of as-produced parts. The aim of this study was to compare the surface and bulk properties of Ti-6Al-4V alloy products obtained using two types of AM—i.e., electron beam melting and direct metal laser sintering—in comparison to the wrought material and analyse their metallographic, crystallographic, topographic, and electrochemical properties. The metallographic and crystallographic, as well as topographic, analysis showed different microstructures and surface area extensions between the tested specimens. Potentiodynamic polarisation tests highlighted the complex electrochemical behaviour of additively manufactured parts if compared to that of the traditionally fabricated ones. The tests performed on mechanically polished parts underlined similar electrochemical performance between them, even if the additive manufactured ones exhibited a certain instability. Although the as-produced additive manufactured parts present exciting surface shapes, useful in the biomedical field, significant drawbacks remain. A more in-depth study of the device surface modifications, to improve their electrochemical behaviour, is needed
Evaluation of roughness and electrochemical behavior of titanium in biological environment
No full textThe increasing use of titanium in the biomedical field arises from the excellent biocompatibility due to the ability to spontaneously become covered with a passive layer. Several studies have shown that some surface treatments can enhance the biological response and corrosion resistance of the implants. The aim of this work is to study the effect of surface treatments of sandblasting and etching with HF on the electrochemical behavior in biological environment and on the roughness of two types of commercially pure titanium, Ti grade 2 and Ti grade 4, used for prostheses and dental implants. The electrochemical characterization has allowed showing that the passive current density increases with the duration of the sandblasting treatment for both alloys. A smaller increase was found in samples subjected to blasting and subsequent etching. It follows that the variation of specific surface induced by blasting is partially canceled by the chemical treatment. The value of passive current density was used to assess the extent of the increase of the real surface of the samples. The roughness analysis showed that the blasting process produces a surface with a large number of peaks, and that the etching with HF tends to level the surface attenuating peaks. The sandblasting and etching treatments, alone or combined, significantly modify the surface of the samples and the magnitude of this change differs depending on the alloy used. Finally, it is proposed to use four roughness parameters to characterize the treated surfaces
Mechanical strength of cold plasma treated PET fibers
No full textIn this work, the effects of cold plasma treatment on the mechanical strength of polyethyleneterephthalate (PET) fibers has been verified. Single fibers were treated with oxygen and a mixture of oxygen and tetrafluoroethylene in a cold plasma reactor for 30, 100 and 200 s. The single fibers were then tested in tensile mode and the mechanical strength was analyzed by using the Weibull distribution function. © 1999 Kluwer Academic Publishers
Designing the Surface of Medical Devices
No full textThe most important properties of metal medical devices are i) biocompatibility, ii) mechanical strength and, in some cases, iii) reliable osseointegration. The surface of biodevices can be designed and then modified to improve these properties. After a brief review of the technologies used to modify the surface of metallic biodevices, some examples of surface treatments used to improve their properties are given. The effect of acid etching on the surface shape of the metal material to improve implant osseointegration, to produce a surface with more ‘valleys’ than ‘peaks’, a requirement for improved osseointegration, is shown. It is demonstrated that the “shape” of the surface can be easily and quantitatively measured by using appropriate roughness parameters. In addition, to reduce the risk of implant rejection, nanoscale reservoirs for controlled drug delivery can be formed on the previously acid-etched implant surface. To this end, the methods used to grow titania nanotube dental screws from commercially pure titania are presented. The shape and length of the nanotubes can be varied to increase or decrease the duration of drug delivery as required
The Electropolishing of Additively Manufactured Parts in Titanium: State of the Art
No full textRecently, additive manufacturing technologies have begun to play a significant role in the industrial field due to the possibility to build complex, near-net-shape, and porous parts, optimizing costs, and time processing. Simultaneously, the high roughness of additively manufactured parts remains a critical drawback, limiting their use like an as-built component. Therefore, postprocessing treatments are needed. The electropolishing (EP) treatment could be ideal for simple, complex, or porous parts characterized by low surface quality. Herein, it is aimed to provide the state of the EP treatment's art carried out, to date, on additively manufactured parts made of titanium and Ti6Al4V alloy. A scientific literature research on EP of additively manufactured titanium and Ti6Al4V alloy is conducted using the Scopus database. The evaluation of recent research, still very few to date, reveals that a significant reduction of the roughness can also be achieved in complex shape additively manufactured parts. Although the EP is a versatile technique to reduce the roughness of additively manufactured parts, further studies are needed to improve its effectiveness, especially for complex and porous structures, to reduce the environmental impact of the materials used
Metallic Biomaterials Surface Engineering
No full textMetals are widely used as biomaterials due to their good thermal conductivity and mechanical and surface properties [...
Corrosion resistance of additive manufactured titanium alloy parts: The effect of recycled powders
No full textThe possibility to reduce costs of the additive manufacturing (AM) technologies by using recycled powders is still an open question. The present paper aims to investigate the effect of using virgin and recycled powders on the corrosion resistance of Ti6Al4V titanium alloy additive manufactured parts. Although the study of the electrochemical behaviour of titanium parts produced by using AM is present in the literature, the corrosion resistance of samples manufactured using recycled powders is less investigated. This work would like to contribute to the deepening of this aspect. The experimental investigations have been carried out on as-built samples as well as on samples after mechanical polishing. The metallographic observations of additive manufactured samples showed a martensitic microstructure inside the prior β grain grew up as columnar structure. X-ray diffraction analysis revealed the presence of titanium oxide in rutile crystallographic phase. The electrochemical characterisation unveiled the lower corrosion resistance of the as-built additive manufactured components compared to the traditional counterpart. It also highlighted the effect due to the use of recycled powders when the bulk of the samples has been investigated
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