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In the present work, a new material design of Ti6Al4V-PEEK hybrid cellular structure with improved wear resistance is proposed. Samples with different dimensions of the open-cells (350, 400, 450, 500 μm) were fabricated by Selective laser melting (SLM) technology, while Hot pressing (HP) technology was employed to produce Ti6Al4V-PEEK hybrid cellular structures. The tribological tests were performed in Phosphate Buffered Saline solution at 37 ± 2 °C. Results demonstrated that the addition of the biomedical PEEK protected the Ti6Al4V cellular structures, thus improving these hybrid structures wear resistance when increasing the amount of PEEK. The obtained results indicated that the Ti6Al4V-PEEK hybrid cellular structure with the dimensions of the open-cells of 500 μm is a suitable structure for orthopedic implants, with improved properties. [ABSTRACT FROM AUTHOR]

The aim of this paper was to study the influence of different surface treatments procedures on tribological behavior of Yttria-tetragonal zirconia polycristals (Y-TZP) against human enamel. The Y-TZP plates were divided into four areas and each area was subjected to a surface treatment according to the groups: GC - no surface treatment, GM – unidirectional milling with high speed tapered bur, GPK – polishing kit Kenda and GPD – polishing kit Diacera. The results demonstrated that the surface treatments play a relevant role on wear behavior of zirconia. In all cases the tooth suffered a greater wear than the Y-TZP plates. In the case of the polished groups it was obtained an improvement on the wear resistance of the tribopair. [ABSTRACT FROM AUTHOR]

The Ti6Al4V alloy constitutes an alternative choice to the most common metal-polymer solutions for total hip arthroplasty (THA) due to good biocompatibility, optimal mechanical properties and high load bearing capacity. However, as Ti6Al4V is not bioactive in its conventional form, hydroxyapatite (HAp) and tricalcium phosphate (TCP) have been widely used as coatings of metal prostheses due to their osteogenic properties and ability to form strong bonds with bone tissue. A promising approach consists in creating a bioactive surface metal matrix composite Ti6Al4V+β-TCP or Ti6Al4V+HAp, obtained by hot pressing (HP) of powders. In this work, the tribological performance of Ti6Al4V+β-TCP and Ti6Al4V+HAp composites is studied to evaluate the frictional response and surface damage representative of prosthesis implantation, key factors in bone fixation. Biocomposites with 10 vol% β-TCP and 10 vol% Hap, as well as base titanium alloy, were prepared by HP with two surface finishing conditions – polished (Ra = 0.3–0.5 μm) and sandblasted (Ra = 2.1–2.5 μm) – for tribological testing against bovine cortical bone tissue. The static friction increases with surface roughness (from 0.20 to 0.60), whereas the kinetic regime follows an inverse trend for the biocomposites. In contrast with current knowledge, this study shows that an implant design solution based on Ti6Al4V+β-TCP or Ti6Al4V+HAp biocomposites with polished surfaces results in an improved primary stability of implants, when compared to traditional rough surfaces. Moreover, it is also expected that the secondary stability will improve due to the adhesion between bone and HAp/β-TCP, increasing the overall stability of the implant. [ABSTRACT FROM AUTHOR]

On modern prosthodontics, CAD/CAM technology is the main manufacturing technique to produce the all-ceramic restorations. Zirconia stabilized with 3%mol of yttria (3Y-TSZ) is the most used material in the production of dental prostheses (e.g. crowns), due to its high biocompatibility, high mechanical strength, oxidation and abrasion resistance, high hardness and fracture toughness. The machining of crowns can produce a waste of approximately 30% of the initial blank, generating a significant economic loss (∼US$ 1087/kg) for the prosthetic laboratories. This work describes the beneficiation of zirconia powder resultant from CAD/CAM milling process, and suggests different applications based on the new properties. Is proposed a recycling solution by mixing the residues with commercial powder with 5, 10 and 50 vol% of residues and prepared by dry mixing, then pressed at 100 MPa and sintered at 1500 °C for 2 h. The quality control of the residues included the particle size distribution, the crystalline phases and chemical composition. For the recycled mixtures it was analyzed the color difference, the microstructure and mechanical properties, as Young and Weibull modulus, and flexural strength, to evaluate the potential uses of this new material. These residues can be used without any additional treatment on applications such as zirconia sand blasting for prosthodontics and as raw material for jewelry, pigment and refractory industries. In the case of the recycled mixtures is suggested the use in jewelry applications, taking advantage of their uniform color and mechanical properties which are similar to hardened noble metals alloys. [ABSTRACT FROM AUTHOR]

The development of new design approaches for biomedical applications using conventional and well accepted bio inert materials is an actual challenge. This study proposes a bilayered materials design approach obtained by hot pressing and is concerned with the influence of sintering pressure on the interface reaction between titanium alloy (Ti6Al4V) and zirconia (ZrO 2 ), on density and mechanical properties of the Ti6Al4V-ZrO 2 . For this purpose, different sintering pressures were studied (P = 5, 20 and 100 MPa). Bilayered materials were produced by hot pressing process, at T = 1175 °C. Microstructural characterization showed that Ti6Al4V reacts with ZrO 2 (for P ≥ 20 MPa) and that the interface reaction is strongly dependent on pressure. Additionally, an oxygen-deficient ZrO 2 − x black zirconia layer was obtained for specimens produced at P = 20 and 100 MPa as result of decreased O/Zr ratio due to Ti diffusion into ZrO 2 side. Young's modulus and hardness properties were evaluated by nanoindentation test. The results showed that these properties are influenced by sintering pressure, increasing with an increase on sintering pressure, with the highest improvement for specimens produced at higher pressure. [ABSTRACT FROM AUTHOR]

This study is concern with tribocorrosion behaviour of Ti6Al4V-HA biocomposites. The Ti6Al4V composites reinforced with different contents of hydroxyapatite (HA) particles 5–15%, vol%) were produced by hot pressing technique. The tribocorrosion tests were performed by using a ball-on-plate configuration in artificial saliva at 37 °C. The tests were carried out under open circuit potential (OCP), with a sliding duration of 1800 s, 1 N normal load and 1 Hz frequency. The open circuit potential and wear mechanisms for all tested biocomposites are presented and discussed. The results suggest that HA plays a relevant role on tribocorrosion behaviour of Ti6Al4V-HA composites. All composites samples presented better wear resistance and also a relatively lower tendency to corrosion with increasing HA content. [ABSTRACT FROM AUTHOR]

Joining cemented carbides and steels is particularly challenging due to the very dissimilar thermal properties that lead to high residual stresses at the interface, where in addition, brittle phases can be formed. An effective carbide-steel joint can unleash the creation of multi-material parts for several applications, and in this sense, it is of utmost importance to develop efficient methods for their fabrication. This work proposes a novel approach, using the high fabrication freedom of laser powder bed fusion technology to additively manufacture 316L stainless steel on a WC-Co substrate, to obtain complex multi-material cutting tools, with dissimilar materials in different locations. Results showed a good bonding between materials, since a dense, well-defined, and capable of withstanding cutting forces interface was obtained. The 316L stainless steel hardness ranges from 238 HV to 302 HV, with a direct correlation being found between the energy density used during laser powder bed fusion and the obtained hardness. This approach was found effective to produce multi-material WC-Co/316L stainless steel cutting tools with good metallurgical bonding and mechanical strength, without the need of adding an interfacial material. [Display omitted] • LPBF proved to be a viable approach for joining cemented carbides to steels. • Good metallurgical and mechanical bonding was achieved with a smooth and narrow interface. • 316L SS hardness varied from 238 HV to 302 HV depending on the energy density. • A direct correlation between energy density and 316L SS hardness was found. • This approach was found effective to produce complex multi-material WC-Co/316L SS cutting tools. [ABSTRACT FROM AUTHOR]

• High-quality Inconel 718-Aluminium parts with no defects, such as pores or cracks. • Good metallurgical bonding with no significant diffusion of elements (5 µm thickness) • Inconel 718-Aluminium specimens display a lower density than the Inc718 bulk (<13 %) • Thermal conductivity Inconel 718-Aluminium was 1.87 times higher than Inconel 718 bulk. In this study, the combination of Inconel 718 (IN718) alloy, widely used in aerospace applications, and a highly conductive low-density Aluminium (Al) was hypothesized to achieve a disruptive solution with improved thermal conductivity and significantly lower weight, key aspects of aerospace industry. A multi-material IN718 – Al solution was designed and later fabricated by combining laser surface texturing and hot-pressing techniques. The multi-material IN718 – Al specimens were produced without significant defects and exhibited a significantly lower density than the IN718 bulk (<13 %), contributing to a weight decrease which can be considered strongly beneficial for improving energy efficiency of aerospace components. The Vickers' microhardness measurements were coherent results with literature and the interface between the two dissimilar materials exhibited a good metallurgical bonding with no significant diffusion of elements. The thermal conductivity of the multi-material IN718 – Al solution was 1.87 times higher than that of IN718 bulk. Multi-material IN718 – Al specimens have shown a high potential to decrease weight and enhance the thermal efficiency of an aerospace component. [ABSTRACT FROM AUTHOR]

Poly-ether-ether-ketone (PEEK) veneers are attractive materials for biomedical contacting surfaces. In the present study, PEEK veneers with thicknesses between 0.1 and 2 mm were synthesized on Ti6Al4V substrates by hot pressing. The influence of PEEK thicknesses on the friction and wear behavior of veneering PEEK to Ti6Al4V structures was studied under reciprocating sliding conditions against an alumina counterbody immersed in artificial saliva at 37 °C. Additionally, numerical simulations were carried out to evaluate the influence of PEEK thickness on the contact stress. The results revealed that the coefficient of friction and the wear rate increased with decreasing the PEEK thickness. It was revealed that the increase of both coefficient of friction and wear rate are correlated with increased contact stress level on PEEK veneer. Such factors are determinant on the long term success of veneering biomedical PEEK to Ti6Al4V for oral applications. [ABSTRACT FROM AUTHOR]

The aim of this paper was to study the interface reaction between an AlSi alloy reinforced with Ni coated Multi-Wall Carbon Nanotubes (MWCNTs). A powder metallurgy processing route was used to produce AlSi composites. SEM, DSC, XRD and TEM analysis showed the formation of Al 3 Ni due to the presence of Al from AlSi matrix and Ni from CNT coating. This contributes to stress transfer from matrix to CNT reinforcement and consequently to enhancement of mechanical properties of the composites. Also it was observed some dissolution of Ni to AlSi and that the CNTs are very stable as they maintain their integrity. The coating of CNTs seems to be a good solution for application of this reinforcement in commercial alloys. [ABSTRACT FROM AUTHOR]

The aim of this work was to investigate the influence of the processing conditions on the tribocorrosion behavior of hot pressed CoCrMo biomedical alloys. Several samples were processed as a function of different processing temperatures (900, 1000 and 1100 °C) and times (10, 30 and 60 min). Tribocorrosion tests were carried out in artificial saliva at 37 °C, under 1 N normal load, 1 Hz frequency and 3 mm stroke length. Open circuit potential was measured. The worn surfaces were inspected by means of SEM/EDS. Results revealed a decrease of wear rate with increasing hot pressing time. The samples hot pressed at 1000 °C revealed the lowest wear rate. These findings showed that the processing conditions play a relevant role on tribocorrosion behavior of CoCrMo. [ABSTRACT FROM AUTHOR]

Lightweight metal-matrix composites (MMC) are being applied in many fields such as aerospace and automotive, where detailed knowledge about their elastic and inelastic properties is required to make optimal design of the component. In this study the high-temperature damping capacity and dynamic Young’s modulus of hot-pressed AlSi-based hybrid composites reinforced with silicon carbide particles (SiC p ) and carbon nanotubes (CNTs) were experimentally measured and compared with AlSi–SiC p and AlSi–CNT composites. Results show that by reinforcing AlSi–SiC p with CNTs, the damping capacity is improved without reducing mechanical properties. The highest damping capacity value was attained by AlSi–(CNT–SiC p ) hybrid composite, for all the studied frequencies and temperatures, followed by AlSi–SiC p and AlSi–CNT composites. The possible damping mechanisms for all these produced composites are presented and discussed. Unlike to damping capacity, the dynamic Young’s modulus shows no substantial changes after adding CNTs to AlSi–SiC p . Results show that by using a proper combination of materials (including different types of reinforcements), scales (nano- and micro-sized reinforcements) and manufacturing processes, the design of a material with required damping capacity and mechanical properties is possible. [ABSTRACT FROM AUTHOR]

The aim of this paper was to study the mechanical behavior of a hybrid AlSi–2 wt.%CNTs–5 wt.%SiCp composite. For comparison purposes the unreinforced AlSi alloy, AlSi–2 wt.%CNTs and AlSi–5 wt.%SiCp composites were used. A powder metallurgy processing route was used to produce the unreinforced AlSi alloy and AlSi composites. Tensile and fatigue tests were performed and the results showed that the hybrid composite AlSi–2 wt.%CNTs–5 wt.%SiCp proposed in the present paper, provided better overall properties than the single reinforcement composites. The improvement is attributed to the combined effects of two different reinforcements that act at different scales. [ABSTRACT FROM AUTHOR]

The effect of SiC particle size on the resultant damping capacity and dynamic modulus of aluminum metal matrix composites (AMMCs) was studied. Damping capacity, as well as dynamic Young's modulus, was measured at 1, 10 and 20 Hz, at room temperature. Image analysis and chemical composition were performed in order to investigate the AlSi–SiC interfacial reaction. The damping capacity of AlSi–SiC p composites, with three different particle size, was compared to AlSi unreinforced. The damping mechanisms involved were discussed in light of the results obtained from damping capacity. The results show that damping capacity and dynamic modulus of AlSi can be improved through the addition of SiC particles. Further, through a selection of specific sizes of SiC particles, it is possible to tailor the final composite stiffness and damping capacity. [ABSTRACT FROM AUTHOR]

Selective Laser Melting (SLM) processing parameters are known to greatly influence 316L stainless steel final properties. A simple energy density calculation is insufficient for explaining mechanical and physical properties as well as microstructural characteristics, which are known to significantly influence these parts performance. In fact, parts produced by using different combinations of processing parameters, even presenting similar energy density, can display different properties. Thus, it is necessary to assess their influence as isolated parameters but also their interactions. This work presents a study on the influence of several SLM processing parameters (laser power, scanning speed and scanning spacing) on density, hardness and shear strength of 316L stainless steel. The influence of these processing parameters on the abovementioned properties is assessed by using statistical analysis. In order to find the significant main factors and their interactions, analysis of variance (ANOVA) is used. Furthermore, in order to assess the effect of the part building orientation, two different building strategies were tested. The influence of these processing parameters on shear strength, hardness and density were assessed for the two building strategies, thus resulting six different models that can be used as predictive design tools. The microstructures experimentally obtained were analyzed, discussed and correlated with the obtained models. [ABSTRACT FROM AUTHOR]

Bioactivity of CoCrMo can be enhanced by incorporation of hydroxyapatite (HAP), but the poor mechanical properties of HAP is the most serious hindrance for its application on load-bearing implants, especially when exposed to corrosion and wear, simultaneously. Thus, the present work aims to investigate the tribocorrosion behaviour of CoCrMo−HAP composites. The tribocorrosion tests were performed under open circuit potential (OCP) in 8 g/l NaCl at 37 ºC by using a ball-on-plate tribometer. Results suggested that HAP particle addition increased the corrosion rate due to localized corrosion taking place on the pore sites near the matrix/reinforcement interface. However, under tribological action, composite samples presented relatively lower tendency to corrosion and lower coefficient of friction values. [ABSTRACT FROM AUTHOR]

The use of metal matrix composite structures in biomedical implants can be a solution for decreasing the amount of degradation products. Thus, the present work aims to investigate the synergism between corrosion and wear on CoCrMo matrix 10% (vol) Al 2 O 3 particle reinforced composites in phosphate buffer solution (PBS) at body temperature. Corrosion behavior was investigated by electrochemical impedance spectroscopy and potentiodynamic polarization. Tribocorrosion tests were performed under open circuit potential, as well as under cathodic and anodic potentiostatic conditions using a reciprocating ball-on-plate tribometer. Results suggest that the addition of Al 2 O 3 particles did not create a significant effect on corrosion behavior of CoCrMo alloy, however, it increased the wear resistance and decreased the corrosion kinetics when sliding in PBS solution. [ABSTRACT FROM AUTHOR]

• Textured areas were produced for further introduction of reinforcement materials. • High-quality Inconel 718 surface grooves were produced by using a Nd: YV0 4 laser. • The use of 0.06 and 0.96 W and 500 and 2000 mm/s laser parameters promote laser ablation. • The grain size was greatly affected by increasing laser power (from 0.06 to 0.96 W). • Development of width and depth mathematical models of the surface grooves. This work presents a detailed study on Inconel 718 alloy surface texturing by a Nd: YVO 4 fibre laser aiming to create localized textured areas for further introduction of reinforcement materials for improvin relevant properties such as thermal conductivity (copper alloys), lightweight (aluminium alloys) or avoid chemical oxidizing reactions (stainless steel alloys). Various laser parameters – there are laser power (P), scan speed (S) and number of passes (N) – and different line spacing (D) were combined. The characterization of the textured surfaces was carried out by scanning electron microscopy (SEM) and analyzed using image analysis software (Image J) to measure the depth and width of the grooves. The textured Inconel 718 specimens were etched to analyze the effect of the laser interaction with the grain morphology. The influence of laser parameters on the grain morphology was assessed by using statistical analysis. In order to find the significant main factors and their interactions an analysis of variance (ANOVA) was used. Results show high-quality textured surfaces are obtained by using low power values and medium scan speed values and remelting areas are produced when considering a low number of passes. Moreover, the grain size is larger when considering high power values when compared with non-textured areas. The mathematical models demonstrated that laser power, scan speed and number of passes affect the depth and width of the grooves. According to its significance, the power (P) is the variable that most affects width of the grooves and the number of passes (N) is the significant variable that most influences the depth variable. [ABSTRACT FROM AUTHOR]

The aim of this paper was to examine the wear behaviour of a hybrid AlSi–2wt%CNTs–5wt%SiCp composite. For comparison purposes the unreinforced AlSi alloy, AlSi–2%wtCNTs and AlSi–5wt%SiCp composites were used. A powder metallurgy processing route was used to produce the unreinforced AlSi alloy and AlSi composites. Dry reciprocating pin-on-plate wear tests were performed and the results showed that the wear behaviour was improved for all produced composites when compared to the unreinforced AlSi alloy. However the best wear behaviour was achieved in the case of AlSi hybrid composite. This improvement is attributed to the combine effects of both constituent reinforcements. The dominant wear mechanisms were characterized by scanning electron microscopy with X-Ray Energy Dispersive Spectrometry analysis. [ABSTRACT FROM AUTHOR]

The damage of piston rings is attributed first to wear, then to lubrication and fatigue. Their damage may be substantially mitigated by creating a FGM-Functionally Graded Material composite with optimized mechanical behavior. The aim of this paper was to produce an AlSi–CNTs functionally graded material (FGM) that can be considered for engine compression piston rings. The AlSi graded composites (reinforced with 0–2 wt.% CNT FGM approach) was obtained with a new equipment that was designed to produce FGMs by powder metallurgy (PM) processing route. SEM analysis showed that the produced FGMs have a gradual change in wt.% of reinforcement and on mechanical properties. Results of yield strength, ultimate tensile strength, tensile strain, fatigue limit performance and wear loss are presented and discussed. It is expected that the obtained AlSi–CNTs functionally graded composite developed for piston rings may have a global equilibrium of properties. [ABSTRACT FROM AUTHOR]

This experimental study is concerned with the influence of metallic (Ti) and ceramic (SiC) reinforcements in an aluminumfsilicon (AlSi) alloy, when regarding tensile properties and wear behavior. Several micron sized particulate reinforced composites were produced by hot-pressing technique: AlSi–SiC and AlSi–Ti composites and AlSi-(Ti–SiC) hybrid composites. Regarding tensile properties, all composites presented higher ultimate tensile strength (UTS) than the AlSi matrix, with the highest UTS being attained by a hybrid composite (AlSi-11.25%Ti–5%SiC). Regarding wear behavior, reciprocating pin-on-plate wear tests were performed for unreinforced AlSi; AlSi–Ti composites and AlSi-(Ti–SiC) hybrid composite against a gray cast iron (GCI) counterface. The wear mechanisms for all the tested tribopairs are presented and discussed. It was observed that the wear behavior of the AlSi–Ti/GCI and also AlSi-(Ti–SiC)/GCI tribopairs are improved when compared with the AlSi/GCI system. AlSi-11.25%Ti-5%SiC hybrid composite exhibited the highest improvement in wear rate. [ABSTRACT FROM AUTHOR]

This study is concerned with the influence of Nickel, as reinforcement, in an aluminum–silicon (AlSi) alloy when regarding wear behavior. For these composites, the effect of Ni content, in the tribopair performance, was evaluated. For this purpose, the pin but also the counterface wear behavior was analyzed. Nickel particulate reinforced aluminum–silicon (AlSi) composites, with 5, 12.5 and 20 wt.% Ni were produced by a hot-pressing route. Microstructural characterization showed a uniform distribution of the Ni particulates in the AlSi matrix. EDS and XRD analyses revealed that the particle/matrix interface was formed by Al 3 Ni intermetallic. Reciprocating pin-on-plate wear tests were performed with AlSi and AlSi–Ni pins against a gray cast iron (GCI) counterface. It was observed that the wear behavior of the AlSi–Ni/GCI tribopair is improved when compared with the AlSi/GCI system. [ABSTRACT FROM AUTHOR]

Highlights: [•] CoCrMo implant materials were produced by hot pressing. [•] HP-CoCrMo samples presented better wear resistance in dry sliding conditions. [•] HP-CoCrMo samples presented comparable wear resistance in tribocorrosion conditions. [•] HP can be considered as a simple and low-cost production route for CoCrMo implants. [ABSTRACT FROM AUTHOR]

WC-Co cutting tools performance under demanding cutting conditions largely depend on the efficiency of the cutting fluid, mainly its ability to remove heat and reduce friction, both highly dependent on the wettability and drop spreading behaviour of the fluid. In this context, this study focuses on the spreading behaviour of machining cutting fluid and water in WC-10 wt%Co cutting tools surface. Contact angles were experimentally measured and then used for performing numerical simulations by the level set method. A contact angle of 75.3˚ and 92.8˚ were measured for the machining cutting fluid and distilled water, respectively, and coincident values were found by numerical simulation, as well as a strong agreement in the drop shape. It was also possible to observe that machining cutting fluid has a lower spreading time than water, due to a lower contact angle and higher viscous dissipation, allowing to reach equilibrium phase sooner. Also, the machining cutting fluid presents a higher drop radius than water, meaning a 24.2% contact area increase over 50 ms of spreading time. Furthermore, numerical simulation showed that the drops spreading over the capillary-inertial time, at the early stage of spreading, follow an exponential dependency with a spreading factor of approximately t 1/2 , which indicates that the initial spreading of both drops is driven and controlled by the balance between inertial and capillary forces. This work intends to contribute to the knowledge on the phenomena that drive the drop spreading behaviour on WC-10 wt%Co cutting tools, being the development of numerical models to predict this behaviour of utmost importance, since it can lead to the development of novel surface improved tools, with an enhanced lubrification effect and heat removal capacity closer to the cutting zone during machining processes, and consequently allowing an improvement in the tribological and cutting performance of these tools. [Display omitted] • Contact angle of 75.3˚ for machining cutting fluid and 92.8˚ for distilled water. • Drop spreading behaviour of both fluids on WC-10wt%Co evaluated by level set method. • Results showed a good agreement between the numerical and experimental drop shape. • Exponential dependency with a spreading factor of approximately t 1/2 . • Initial spreading stage controlled by balance between inertial and capillary forces. [ABSTRACT FROM AUTHOR]

Orthopaedic implants for load-bearing applications are usually composed of titanium-based materials. Aiming to propose a strategy able to improve the bone-implant interface on these implants, commercially pure titanium and Ti6Al4V alloy were subjected to anodic oxidation, hydrothermal treatment and to anodic oxidation followed by hydrothermal treatment and the produced oxide film was investigated. In addition, different mechanical (as-received vs mechanical polished) and chemical pre-treatments (alcohol cleaning vs acidic pre-treatment) were studied. No significant differences were found between the chemical pre-treatments, whereas upon different surface treatments the TiO 2 layer presented different characteristics, namely regarding its crystallinity, roughness, thickness and wettability. The hydrothermal treatment followed by immersion for 24 h in 5XPBS was effective in creating a potentially bioactive oxide film, given the presence of anatase and rutile phases, and a hydrophilic layer for both Ti materials. Ti grade 2 subjected to alcohol cleaning and hydrothermal treatment resulted in a surface roughness of 226.7 ± 3.1 nm and water contact angle of 67.2 ± 8.7°, whereas for the Ti grade 5 subjected to the same surface treatment, Ra was equal to 20.4 ± 1.7 nm and the water contact angle to 83.5 ± 4.7°. In this context, the hydrothermal treatment is proposed as a simple treatment capable of improving the characteristics of the implant surface, thereby promoting osteoconductivity. [Display omitted] • Titanium grade 2 and Ti6Al4V were used as substrates for surface modification. • Oxide films produced by different surface treatments were extensively characterized. • No substantial differences were found between alcohol and acidic pre-treatments. • A potentially bioactive and hydrophilic layer was obtained by hydrothermal treatment. • Hydrothermal treatment is the strategy proposed to enhance the bone-implant interface. [ABSTRACT FROM AUTHOR]

In this study, a multi-material NiTi-PEEK cellular structured solution was designed, produced and characterized targeting orthopedic applications. For that purpose, Selective Laser Melting (SLM) technique was used to produce NiTi cellular structures with different open-cell sizes and wall thicknesses. Hot Pressing (HP) technique was used to introduce PEEK in the open-cells of NiTi structures to obtain multi-material components. Morphological characterization showed that the selected SLM processing parameters were suited to achieve high-quality parts without significant defects. Tribological characterization proved an enhanced wear resistance to the multi-material specimens when compared with the mono-material NiTi structures. These multi-material structures are a promising solution for providing a customized stiffness and superior wear resistance to NiTi structures to be integrated in innovative orthopedic designs. Image 1 • NiTi-PEEK multi-material structures were produced by SLM with HP techniques. • These structures can provide a customized stiffness and superior wear resistance. • Tribological tests were performed for mono and multi-material structures. • Wear results revealed an enhanced wear performance for multi-material structures. [ABSTRACT FROM AUTHOR]

• A hybrid approach for printing micro-wires on zirconia substrate were presented. • The resistivity of the micro-wires was assessed by the four-probe method. • The mechanical performance of zirconia before and after wire printing was presented. • Laser technology was successfully used both to create channel and sinter silver powder inside them. Smart implants are endowed with functions of sensing, actuating and control to solve problems that may arise during their use. The assembly of these functions along the implant surface is still a challenge. However, with the advent of 3D printing, it is possible to print on implants' surface, communication channels or micro-antennas or even sensoric/actuating areas. Hence, a positive impact on the long-term performance of the implants (including hip, dental and knee) may be expected with the proposed approach. Despite titanium and Ti6Al4V titanium alloy are the standard choice for implants fabrication, 3Y-TZP (tetragonal 3% mol yttria-stabilized zirconia) has emerged as a ceramic material suitable to overcome titanium alloy problems, due to its numerous advantages. In this sense, this work is concerned with the ability of printing silver-based communication system in zirconia substrates by using laser technology. For this purpose, micro-cavities were created on ZrO 2 substrate, where the silver powder was placed and sintered into them. Through the laser approach, silver-based wires with great quality and low resistivity values were achieved. The flexural strength results showed that the mechanical resistance of zirconia disks was affected by laser micro-wire printing, which decreased as the laser passage was performed. Based on the results, it is believed that the proposed approach seems to be effective for the manufacturing of implants with intrinsic capacities, useful for smart implant applications. [ABSTRACT FROM AUTHOR]

• NiTi-Ti6Al4V multi-material structures were designed and produced by SLM; • A commercial equipment (SLM 125 HL from SLM Solutions) was used; • Effective bonding between the materials in the transition region was achieved; • Shear bond strength of ≈33 MPa was obtained for the multi-material structures; • The fabrication strategy and the SLM processing parameters were validated; The amount of hip revision surgeries is significantly increasing due to the loss of fixation between implant and bone, that leads to implant failure. The stiffness mismatch between Ti6Al4V hip implants and bone tissue, the non-uniform implant-bone contact pressure, and the poor wear resistance of Ti6Al4V are pointed as three critical issues that contribute to these implant's failure. In this study, a multi-material design and fabrication concept was exploited aiming to change traditional manufacturing paradigms, by allocating different biomaterials in a single component targeting a multi-functional hip implant. Selective Laser Melting technology was explored to fabricate NiTi-Ti6Al4V multi-material cellular structures with a Ti6Al4V inner region and a NiTi outer region. This work was focused on the SLM fabrication and processing parameters validation on a commercial SLM equipment. The morphological analyses allowed to assess a successful solidification and bond between NiTi and Ti6Al4V materials in the transition region. The shear tests revealed a high bond strength of the transition region with an average strength of 33 MPa. The nano-indentation results showed that the Ti6Al4V region exhibits a higher hardness and elastic modulus when compared with the NiTi region. This work is a part of a broader objective that aims to create a NiTi-Ti6Al4V multi-material and cellular structured hip implant capable to provide customized stiffness, superior wear resistance and a controlled NiTi outer region volume change. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• A hybrid approach for printing micro-wires on titanium substrate were presented. • The resistivity of the micro-wires was assessed via experimental and computational. • A comparative study between laser and anodizing for insulation layer was performed. • Laser technology was successfully used in additive and subtractive approaches. Endow the implant with intrinsic communication system between sensors and actuators or between implant and patient is a key factor for its long-term success. The capacity of early diagnosis of failures and the ability to remedy them are necessary to minimize expensive complications and reducing revision procedures. Ti6Al4V is the most used titanium alloy for implant's fabrication. In this sense, this work presents a promising approach to print communication systems by using laser technology, aiming integrate the smart components on titanium implants. Laser has been employed as a versatile tool to modify the surface in different ways, such as texturing, oxidizing and sintering. Silver wires have been printed on Ti6Al4V surface in order to conduct electrical current. To minimize current loss for the substrate, titanium oxide layer has been produced by different methods (laser and anodization). Laser sintering (LS) has been also compared to a conventional method (Hot-pressing- HP) to consolidate the silver powder into the cavities. In comparison to the conventional techniques, laser demonstrated to be a competitive approach to oxidizing the surface and also for consolidating the micro-wires on Ti6Al4V surface. Consequently, the micro-wires printed by laser approach presented satisfactory results in terms of electrical resistance, actuating as the conductor path for electrical current, with values of 0.0131 Ω, which is similar to the resistance of the wire printed in an insulator substrate. [ABSTRACT FROM AUTHOR]

Two composite blends of CuCoBe and synthetic diamond with different particle sizes, (0.1–0.5 μm and 40–60 μm), were obtained by mechanical alloying and were used as a reinforcement of a laser textured 316L stainless steel in this work. Consolidation/sintering of the powders was conducted by hot pressing. From all the samples studied, the 316L stainless steel reinforced with the CuCoBe + diamond (40–60 μm) composite presented the lowest values of specific wear rate and coefficient of friction (5.83 × 10−7 mm3/N.m and 0.14, respectively), showing the potential of this material in applications where good tribological behaviour is required, e.g. for the fabrication of improved automotive piston rings. • New approach for producing textured diamond-reinforced 316L steel matrix composites. • This new approach might be used to selectively reinforce functional surfaces. • Reinforced 316L steel matrix composites with improved tribological properties. [ABSTRACT FROM AUTHOR]

Laser texturing is a technique that has been increasingly explored for the surface modification of several materials on different applications. Laser texturing can be combined with conventional coating techniques to functionalize surfaces with bioactive properties, stimulating cell differentiation and adhesion. This study focuses on the cell adhesion of laser-sintered coatings of hydroxyapatite (HAp) and 45S5 bioactive glass (45S5 BG) on zirconia textured surfaces using MC3T3-E1 cells. For this purpose, zirconia surfaces were micro-textured via laser and then coated with HAp and 45S5 BG glass via dip coating. Afterwards, the bioactive coatings were laser sintered, and a reference group of samples was conventionally sintering. The cell adhesion characterisation was achieved by cell viability performing live/dead analysis using fluorescence stains and by SEM observations for a qualitative analysis of cell adhesion. The in vitro results showed that a squared textured pattern with 100 μm width grooves functionalized with a bioactive coating presented an increase of 90% of cell viability compared to flat surfaces after 48 h of incubation. The functionalized laser sintered coatings do not present significant differences in cell viability when compared to conventionally sintered coatings. Therefore, the results reveal that laser sintering of HAp and 45S5 BG coatings is a fast and attractive coating technique. • Production of squared textures on zirconia substrates by laser texture technique • Production of bioactive coatings using different powders via laser sintering • No chemical differences between laser-sintered and conventionally sintering • Increase of 90% cell viability using laser sintered bioactive coatings • Mechanism of cell layer formation based on four stages of cells proliferation [ABSTRACT FROM AUTHOR]

The development of new surface designs to enhance the integration process between surgically placed implants and biological tissues remains a challenge for the scientific community. In this way and trying to overcome this issue, in this work, laser technology was explored to produce novel textures on the surface of green zirconia compacts produced by cold pressing technique. Two strategies regarding line design (8 and 16 lines design) and different laser parameters (laser power and number of laser passages) were explored to assess their influence on geometry and depth of created textures. The produced textures were evaluated with Scanning Electron Microscopy (SEM) and it was observed that well-defined textured surfaces with regular geometric features (cavities or pillars) were obtained by laser combining different strategies lines design and parameters. The potential of proposed textures was also evaluated regarding surface wettability, friction performance (static and dynamic coefficient of friction evolution) against bone, aging resistance and flexural strength. Results demonstrated that all the produced textures display a super hydrophilic or hydrophilic behavior. Regarding the friction behavior, it was experimentally observed a high initial static coefficient of friction (COF) for all produced textures. Concerning the aging resistance, all the textured surfaces revealed a low monoclinic content, less than 25% after 5 h of hydrothermal aging. The flexural strength results showed that the mechanical resistance of zirconia was not significantly compromised with the laser action. Based on the obtained results, it is possible to prove that the processing route used for manufacturing the new and different surface designs (cold pressing technique followed by laser texturing) showed to be particularly effective for the production of zirconia implants with customized surface designs according to the properties required in a specific application. These new surface designs besides to enhance the surface wettability and also to improve the fixation at the initial moment of the implantation, do not significantly compromise the resistance to aging and the mechanical performance of zirconia. Hence, a positive impact on the long-term performance of the zirconia implants may be expected with the proposed novel laser textured surface designs. Image 1 • Laser texturing was proven effective for producing novel surface designs on ZrO 2. • Laser parameters and strategies had influenced the geometry and depth of textures. • ZrO 2 surface textures with improved wettability and primary stability are proposed. • ZrO 2 aging resistance and mechanical behavior were not greatly affected by the laser. • This approach showed to be a promising way to produce customized surface implants. [ABSTRACT FROM AUTHOR]

Orthopedic implants are under incessant advancement to improve their interactions with surrounding bone tissue aiming to ensure successful outcomes for patients. A successful biological interaction between implant and surrounding bone depends on the combination of mechanical, physical and topological properties. Hence, Ti6Al4V cellular structures appear as very promising solutions towards the improvement of conventional orthopedic implants. This work addresses a set of fundamental tools that allow improving the design of Ti6Al4V cellular structures produced by Selective Laser Melting (SLM). Three-point bending tests were carried out to estimate the elastic modulus of the produced structures. Morphological analysis allowed to evaluate the dimensional differences that were noticed between the model CAD and the SLM structures. Finite element models (adjusted CAD) were constructed with the experimentally obtained dimensions to replicate the mechanical response of the SLM structures. Linear correlations were systematically found for the dimensions of the SLM structures as a function of the designed model CAD dimensions. This has also been observed for the measured porosities as a function of the designed CAD models. This data can be used in further FE analyses as design guidelines to help engineers fabricating near-net-shape SLM Ti6Al4V cellular structures. Besides, polished and sandblasted surface treatments performed on the Ti6Al4V cellular structures allowed to obtain suitable properties regarding roughness and wettability when compared to as-produced surfaces. The capillarity tests showed that all the analyzed Ti6Al4V structures are able to transport fluid along its structure. The cell viability tests demonstrate Ti6Al4V cellular structures SLM produced did not release toxic substances to the medium, indicating that these structures can assure a suitable environment for cells to proliferate and attach. This study proposes a design methodology for Ti6Al4V cellular structures, that owe suitable mechanical properties but also provide a proper combination of porosity, roughness, wettability, capillarity and cell viability, all of them relevant for orthopedic applications. A Ti6Al4V cellular structured hip implant prototype gathering the suitable features addressed in this study was successfully SLM-produced. • Linear correlations between SLM produced and CAD structures dimensions are proposed. • Suitable elastic modulus is obtained by Ti6Al4V cellular structure with ≈65% porosity. • Cell viability tests prove that SLM structures do not release toxic substances. • Super hydrophilic behavior is obtained for polished and sandblasted surfaces. • A Ti6Al4V cellular structured hip implant prototype was fabricated by SLM. [ABSTRACT FROM AUTHOR]

• The successful chemical route to synthesis ZnO and its surface modification. • Coating with simultaneous photocatalytic/hydrophobic properties. • Modification of water contact angle with UV radiation. • Changes of water contact angle at low temperature. • Efficient dye degradation by ZnO/PDMS nanocomposite. The polydimethylsiloxane (PDMS)/ZnO nanocomposite coatings were deposited on the borosilicate substrate by spray method. ZnO nanoparticles were synthesized by polyol method and further surface modification by functionalization with [(3-Aminopropyl)triethoxysilane] (APTS) in different concentrations (0.5, 1.0, and 1.5 ml). The results showed that there is an influence in the exposure to UV radiation and a decrease in the temperature, consequently presenting decreases in the contact angle of ZnO/PDMS nanocomposites. The 0.5 ml of APTS was the best design for ZnO/PDMS nanocomposite with photocatalytic and hydrophobic characteristics, showing a contact angle of 117° and 25% of MB discoloration in 90 min. [ABSTRACT FROM AUTHOR]