Applicative Assessment of a Selective Laser Melting 3D-Printed Ti-6Al-4 V Plate with a Honeycomb Structure in the Reconstruction of a Mandibular Defect of a Beagle Dog.

The most challenging problem in oral and maxillofacial surgery is the reconstruction of defects for the oral and maxillofacial complex. Transfer of different autografts is known as the "gold standard" for the reconstruction of bone defects in the oral and maxillofacial region. Graft harvesting, however, can lead to many complications, such as donor-site morbidity, surgical time-consuming, etc. Three-dimensional (3D) printing technology is an innovative technique that allows the fabrication of personalized plates and scaffolds to fit the precise anatomy of an individual's defect. In this study, a selective laser melting 3D-printed Ti-6Al-4 V plate with a honeycomb was designed, and its physical and biological features were characterized. The personalized 3D-printed scaffold and commercialized titanium reconstruction plate were applied to reconstruct a 4 cm mandibular defect in a beagle dog. Effects of the treatment were analyzed radiologically and histologically. Our results showed that the application of a 3D-printed plate with a honeycomb achieved good biocompatibility and osseointegration and has potential clinical application.

Copper-containing titanium alloys promote the coupling of osteogenesis and angiogenesis by releasing copper ions.

Previous investigations have reported on the ability of copper (Cu)-bearing biomaterials to accelerate vascular formation and bone regeneration. However, few studies have explored the effects of Cu-bearing materials on the interactions between angiogenesis and osteogenesis. Therefore, in this study, we prepared Cu-containing alloys using selective laser melting (SLM) technology and investigated the impact of preosteoblasts seeded on Ti6Al4V-4.5Cu alloy on angiogenesis. Our results indicated that Ti6Al4V-4.5Cu alloys increased the expression of proangiogenic genes and proteins in preosteoblasts, which further stimulated vascular formation in endothelial cells. Besides, we discovered that the biological effects of the Ti6Al4V-4.5Cu alloy were partly attributed to the release of Cu ions. In short, our research demonstrated the ability of Ti6Al4V-4.5Cu alloys to promote the coupling of angiogenesis and osteogenesis by releasing Cu ions.

Organic-inorganic hybrid nanoflowers as a new biomimetic platform for ROS-induced apoptosis by photodynamic therapy.

We report here a newly and facile synthesis of the phospholipids@gold nanoflowers (AuNFs) from intact cells as a new biomimetic organic-inorganic hybrid. The most appealing feature of this nanostructure is its dual-absorbing peak in near infrared (NIR) and visible region of spectra, which makes them a potential light-sensitive agent for reactive oxygen species (ROS)-induced apoptosis. Here, in contrast to previous studies, proposed nanostructures are synthesized in a one-pot reaction using phospholipids present in living cell membranes (as a donor cell) with detectable micro process of AuNF formation. The properties of the resulting AuNFs were evaluated through transmission electron microscopy (TEM), as well as FT-IR, 31P-NMR spectra and UV-Vis spectroscopy. Designed cell membrane-based nanostructure looks like an intact cell and would be able to interact with other cells (as a target cell) and also capable to produce cytotoxic singlet oxygen under NIR irradiation. Generated ROS act as a key player in initiation of programmed cell death (apoptosis) and progress of cancer photodynamic therapy (PDT). Cellular experiments on breast cancer MCF-7 cells demonstrated that they may be effective as photodynamic therapy agents.

Antibacterial performance of a porous Cu-bearing titanium alloy by laser additive manufacturing.

Porphyromonas gingivalis (P. gingivalis) is the most common species that causes peri-implantitis. It forms an irreversible dense biofilm and causes inflammation. A novel 3D-printed porous TC4-6Cu alloy was fabricated using selective laser melting (SLM) technology for the dental implant, which is anticipated to inhibit biofilm formation. We attempted to investigate the antibacterial ability and antibacterial mechanism of the 3D-printed porous TC4-6Cu alloy against P. gingivalis. This work used scanning electron microscopy (SEM) and laser confocal microscopy (CLSM) to detect the antimicrobial ability of the alloy against sessile P. gingivalis. The results indicated that the 3D-printed porous TC4-6Cu alloy could cause bacterial fragmentation and deformation. Plate antimicrobial counting experiments showed that the antibacterial rates of the alloy against adherent bacteria and planktonic bacteria after 24 h were 98.05% and 73.92%, respectively. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Cu2+ were tested to appraise the antibacterial property of the alloy against planktonic P. gingivalis. The relationship between the antibacterial mechanism of the alloy with oxidative stress was evaluated through ROS fluorescence intensity and protein leakage concentration. The results revealed that the alloy significantly eliminated adherent bacteria and inhibited biofilm formation. Moreover, 3D-printed porous TC4-6Cu alloy demonstrated significant bactericidal ability by inducing the production of reactive oxygen species (ROS), which could result in protein leakage from the bacterial cell membrane. This research may open a new perspective on the development and biomedical applications for dental implantation.

An efficient and convenient Fiber -2- based latex agglutination test for the detection of antibodies against fowl adenovirus serotype 4 in clinical samples.

To detect the antibody against fowl adenovirus serotype 4 (FAdV-4) in clinical practice, the latex agglutination test (LAT) was developed by using the Fiber-2 protein of FAdV-4 as an antigen bound to sensitized latex microspheres. The concentration, time, and temperature of sensitization latex microspheres by the Fiber-2 protein were studied and optimized; the specificity, sensitivity, and repeatability of LAT were tested; and the method developed in the study was applied. The results showed that the optimum sensitization concentration of Fiber-2 protein was 0.8 mg/mL, the time was 120 min, and the temperature was 37 â„ƒ. Except for antiserum against FAdV-4 and FAdV-10, LAT developed in the study could not agglutinate antisera against FAdV-1, FAdV-2, FAdV-3, FAdV-4, FAdV-5, FAdV-6, FAdV-8a, FAdV-8b, FAdV-11, Newcastle disease virus, infectious bronchitis virus, egg drop syndrome virus and Clostridium perfringens. Compared with the commercial FAdV-4 ELISA Kit, the titers in 21 clinical samples were low when tested by the developed LAT method, but there was no significant difference. The coefficients of variation among different batches and the same batch of latex-sensitized particles were between 0 % and 13.3 % and 0-8.7 %, respectively. The critical value of immune protective antibody against FAdV-4 was 25, and the titers in 40.9 % of clinical samples were higher than the immune critical point. The results showed that the Fiber-2-based LAT developed in the study has the characteristics of high specificity, sensitivity and repeatability, has the advantages of free equipment, long shelf life, and fast and easy operation, and is an effective and convenient method for serological diagnosis of FAdV-4 infection and evaluating the efficacy of vaccines.

Copper modified cobalt-chromium particles for attenuating wear particle induced-inflammation and osteoclastogenesis.

The nature of aseptic prosthetic loosening mainly relates to the wear particles that induce inflammation and subsequent osteoclastogenesis. The ideal approach to impede wear particle-induced osteolysis should minimize inflammation and osteoclastogenesis. In this work, Co29Cr9W3Cu particles were used as a research model for the first time to explore the response of Co29Cr9W3Cu particles to inflammatory response and osteoclast activation in vitro and in vivo by using Co29Cr9W particles as the control group. In vitro studies showed that the Co29Cr9W3Cu particles could promote the generation of M2-phenotype macrophages and increase the expression level of anti-inflammatory factor IL-10, while inhibiting the formation of M1-phenotype macrophages and down-regulating the expression of inflammatory factors TNF-α, IL-6 and IL-1ß; More importantly, the Co29Cr9W3Cu particles reduced the expression of NF-κB and downstream osteoclast related-specific transcription marker genes, such as TRAP, NFATc1, and Cath-K; In vivo results indicated that the Co29Cr9W3Cu particles exposed to murine calvarial contributed to decreasing the amount of osteoclast and osteolysis area. These findings collectively demonstrated that Cu-bearing cobalt-chromium alloy may potentially delay the development of aseptic prosthetic loosening induced by wear particles, which is expected to provide evidence of Co29Cr9W3Cu alloy as an alternative material of joint implants with anti-wear associated osteolysis.

Copper-containing titanium alloys promote angiogenesis in irradiated bone through releasing copper ions and regulating immune microenvironment.

Poor vascularization was demonstrated as a factor inhibiting bone regeneration in patients receiving radiotherapy. Various copper-containing materials have been reported to increase angiogenesis, therefore might improve bone formation. In this study, a Ti6Al4V-1.5Cu alloy was prepared using selective laser melting (SLM) technology. The immunomodulatory and pro-angiogenic effects of the Ti6Al4V-1.5Cu alloys were examined. In vitro, Ti6Al4V-1.5Cu stimulated vascular formation by restraining inflammatory factors and provoking angiogenic factors in non-irradiated and irradiated macrophages. In vivo, the angiogenic effects of the Ti6Al4V-1.5Cu alloy were confirmed using an irradiated rat femur defect model. Moreover, we found that the biological effects of the Ti6Al4V-1.5Cu alloy were partially due to the release of copper ions and associated with PI3K-Akt signaling pathway. In conclusion, this study indicated the potential of the Ti6Al4V-1.5Cu alloy to promote angiogenesis by releasing copper ions and inhibiting inflammation in normal and irradiated tissues.

Corrosion Resistance of Selective Laser Melted Ti6Al4V3Cu Alloy Produced Using Pre-Alloyed and Mixed Powder.

Metallic elemental powder mixture and pre-alloyed metallic powder are both frequently used powder feedstock in the additive manufacturing process. However, little research has been conducted to compare the corrosion behavior of selective laser melting (SLM) alloys, fabricated by pre-alloyed metallic powder and mixed metallic powder. Hence, it is important to investigate the corrosion behavior of SLMed alloys, as well as the corresponding cast ingot, with the aim to better understand the feasibility of designing new materials. In this work, the SLM-produced Ti6Al4V3Cu alloys were manufactured using a metallic elemental powder mixture and pre-alloyed metallic powder, respectively. The corrosion behavior of the different Ti6Al4V3Cu alloys was investigated in following electrochemical tests and ion release measurements. The results showed that the Ti6Al4V3Cu alloy prepared by pre-alloyed metallic powder showed better corrosion resistance than that produced from mixed metallic powder. Moreover, the SLM-produced Ti6Al4V3Cu alloys performed significantly better in corrosion resistance than the cast Ti6Al4V3Cu. The results are expected to achieve a better understanding of the feasibility of designing new materials using mixed powders, contributing to reducing development costs and cycles.

Tuning osteoporotic macrophage responses to favour regeneration by Cu-bearing titanium alloy in Porphyromonas gingivalis lipopolysaccharide-induced microenvironments.

Guided bone regeneration in inflammatory microenvironments of osteoporotic patients with large alveolar bone defects remains a great challenge. Macrophages are necessary for alveolar bone regeneration via their polarization and paracrine actions. Our previous studies showed that Cu-bearing Ti6Al4V alloys are capable of regulating macrophage responses. When considering the complexity of oral microenvironments, the influences of Cu-bearing Ti6Al4V alloys on osteoporotic macrophages in infectious microenvironments are worthy of further investigations. In this study, we fabricated Ti6Al4V-Cu alloy by selective laser melting technology and used Porphyromonas gingivalis lipopolysaccharide (P.g-LPS) to imitate oral pathogenic bacterial infections. Then, we evaluated the impacts of Ti6Al4V-Cu on osteoporotic macrophages in infectious microenvironments. Our results indicated that Ti6Al4V-Cu not only inhibited the P.g-LPS-induced M1 polarization and pro-inflammatory cytokine production of osteoporotic macrophages but also shifted polarization towards the pro-regenerative M2 phenotype and remarkably promoted anti-inflammatory cytokine release. In addition, Ti6Al4V-Cu effectively promoted the activity of COMMD1 to potentially repress NF-κB-mediated transcription. It is concluded that the Cu-bearing Ti6Al4V alloy results in ameliorated osteoporotic macrophage responses to create a favourable microenvironment under infectious conditions, which holds promise to develop a GBR-barrier membrane for alveolar bone regeneration of osteoporosis patients.

[Three-dimensional printed Ti6Al4V-4Cu alloy promotes osteogenic gene expression through bone immune regulation].

OBJECTIVE: To investigate the effects of three-dimensional (3D) printed Ti6Al4V-4Cu alloy on inflammation and osteogenic gene expression in mouse bone marrow mesenchymal stem cells (BMSCs) and mouse mononuclear macrophage line RAW264.7. METHODS: Ti6Al4V and Ti6Al4V-4Cu alloys were prepared by selective laser melting, and the extracts of the two materials were prepared according to the biological evaluation standard of medical devices. The effects of two kinds of extracts on the proliferation of mouse BMSCs and mouse RAW264.7 cells were detected by cell counting kit 8 method. After co-cultured with mouse BMSCs for 3 days, the expression of osteogenesis- related genes [collagen type Ⅰ (Col-Ⅰ), alkaline phosphatase (ALP), Runx family transcription factor 2 (Runx-2), osteoprotegerin (OPG), and osteopontin (OPN)] were detected by real-time fluorescence quantitative PCR. After co-cultured with mouse RAW264.7 cells for 1 day, the expressions of inflammation-related genes [interleukin 4 (IL-4) and nitric oxide synthase 2 (iNOS)] were detected by real-time fluorescence quantitative PCR, and the supernatants of the two groups were collected to detect the secretion of vascular endothelial growth factor a (VEGF-a) and bone morphogenetic protein 2 (BMP-2) by ELISA. The osteogenic conditioned medium were prepared with the supernatants of the two groups and co-cultured with BMSCs for 3 days. The expressions of osteogenesis-related genes (Col-Ⅰ, ALP, Runx-2, OPG, and OPN) were detected by real-time fluorescence quantitative PCR. RESULTS: Compared with Ti6Al4V alloy extract, Ti6Al4V-4Cu alloy extract had no obvious effect on the proliferation of BMSCs and RAW264.7 cells, but it could promote the expression of OPG mRNA in BMSCs, reduce the expression of iNOS mRNA in RAW264.7 cells, and promote the expression of IL-4 mRNA. It could also promote the secretions of VEGF-a and BMP-2 in RAW264.7 cells. Ti6Al4V-4Cu osteogenic conditioned medium could promote the expressions of Col-Ⅰ, ALP, Runx-2, OPG, and OPN mRNAs in BMSCs. The differences were all significant ( P<0.05). CONCLUSION: 3D printed Ti6Al4V-4Cu alloy can promote RAW264.7 cells to secret VEGF-a and BMP-2 by releasing copper ions, thus promoting osteogenesis through bone immune regulation, which lays a theoretical foundation for the application of metal prosthesis.

Copper-modified Ti6Al4V alloy fabricated by selective laser melting with pro-angiogenic and anti-inflammatory properties for potential guided bone regeneration applications.

Custom-made biocompatible titanium alloy mesh can be designed to facilitate the regeneration of alveolar bone defects by supporting a protected space and inhibiting bacterial infections. Copper ions are often incorporated into titanium alloy due to their high bioactivity and outstanding antibacterial properties. However, the impacts of copper-bearing alloys on peri-implanted cell behaviors have rarely been systematically explored. In the present study, a copper-bearing alloy (Ti6Al4V-6Cu) was fabricated by selective laser melting (SLM) technology. The characterization of Ti6Al4V-6Cu alloy and its effects on the behaviors of gingival fibroblasts (HGFs), human umbilical vein endothelial cells (HUVECs), osteoblasts and macrophages were evaluated and compared with Ti6Al4V. The diffraction peaks of the Ti2Cu intermetallic phase were observed in the Ti6Al4V-6Cu alloy. Adding Cu enhanced the release of Ti and Al ions. The chemical state of Cu in the Ti6Al4V-6Cu alloy may exist predominantly in Cu2O or TiCuOx. Ti6Al4V-6Cu did not affect the attachment of HGFs or the osteogenic activity of osteoblasts. Furthermore, it inhibited the activation, proliferation, and pro-inflammatory cytokine secretion of macrophages and upregulated angiogenesis-related gene expression and VEGF-A secretion of HUVECs. These results demonstrate that a Ti6Al4V-6Cu alloy was successfully fabricated that did not negatively impact the cell viability of gingival fibroblasts and osteoblasts, inhibited the inflammatory response of macrophages, and increased the angiogenesis of HUVECs. Thus, Ti6Al4V-6Cu has potential applications for the fabrication of titanium alloy mesh to promote alveolar bone regeneration.

The effect of 3 wt.% Cu addition on the microstructure, tribological property and corrosion resistance of CoCrW alloys fabricated by selective laser melting.

Microstructure, tribological property and corrosion resistance of orthopedic implant materials CoCrW-3 wt.% Cu fabricated by selective laser melting (SLM) process were systematically investigated with CoCrW as control. Equaxied γ-phase together with the inside {111} < 112 > type twin and platelet ε-phase was found in both the Cu-bearing and Cu-free alloys. Compared to the Cu-free alloy, the introduction of 3 wt.% Cu significantly increased the volume fraction of the ε-phase. In both alloys, the hardness of ε-phase zone was rather higher (~4 times) than that of γ-phase zone. The wear factor of 3 wt.% Cu-bearing alloy possessed smaller wear factor, although it had higher friction coefficient compared with Cu-free alloys. The ε-phase in the CoCr alloy would account for reducing both abrasive and fatigue wear. Moreover, the Cu-bearing alloy presented relatively higher corrosion potential Ecorr and lower corrosion current density Icorr compared to the Cu-free alloy. Accordingly, 3 wt.% Cu addition plays a key role in enhancing the wear resistance and corrosion resistance of CoCrW alloys, which indicates that the SLM CoCrW-3Cu alloy is a promising personalized alternative for traditional biomedical implant materials.

Effect of Cu on microstructure, mechanical properties, corrosion resistance and cytotoxicity of CoCrW alloy fabricated by selective laser melting.

In the study, CoCrWCu alloys with differing Cu content (2, 3, 4 wt%) were prepared by selective laser melting using mixture powders consisting of CoCrW and Cu, aiming at investigating the effect of Cu on the microstructures, mechanical properties, corrosion behavior and cytotoxicity. The SEM observations indicated that the Cu content up to 3 wt% caused the Si-rich precipitates to segregate along grain boundaries and in the grains, and EBSD analysis suggested that the Cu addition decreased the recrystallization degree and increased the grain diameter and fraction of big grains. The tensile tests found that the increasing Cu content led to a decrease of mechanical properties compared with Cu-free CoCrW alloy. The electrochemical tests revealed that the addition of Cu shifted the corrosion potential toward nobler positive, but increased the corrosion current density. Also, a more protective passive film was formed when 2 wt% Cu content was added, but the higher Cu content up to 3 wt% was detrimental to the corrosion resistance. It was noted that there was no cytotoxicity for Cu-bearing CoCrW alloys to MG-63 cell and the cells could spread well on the surfaces of studied alloys. Meanwhile, the Cu-bearing CoCrW alloy exhibited an excellent antibacterial performance against E.coli when Cu content was up to 3 wt%. It is suggested that the feasible fabrication of Cu-bearing CoCrW alloy by SLM using mixed CoCrW and Cu powders is a promising candidate for use in antibacterial oral repair products. This current study also can aid in the further design of antibacterial Cu-containing CoCrW alloying powders.

Copper-Modified Ti6Al4 V Suppresses Inflammatory Response and Osteoclastogenesis while Enhancing Extracellular Matrix Formation for Osteoporotic Bone Regeneration.

Copper has been reported to promote bone regeneration by increasing osteogenesis and decreasing inflammation and osteoclastogenesis. However, information on the effects of copper on osteoporotic cells involved in bone regeneration is scarce in the literature. In the current study, Ti6Al4 V-6 wt %Cu (Ti6Al4 V-Cu) was fabricated by selective laser melting (SLM) technology, and the effects of copper on the behaviors of osteoporotic and nonosteoporotic macrophages, osteoclasts, and osteoblasts were evaluated by comparison with Ti6Al4 V. Our results showed that Ti6Al4 V-Cu inhibited the activation, viability, and pro-inflammatory cytokine secretion of osteoporotic macrophages and decreased osteoclast formation and down-regulated osteoclast differentiation-related genes and proteins of osteoporotic osteoclasts. Furthermore, the bone extracellular matrix formation of osteoporotic osteoblasts was up-regulated by Ti6Al4 V-Cu. In conclusion, SLM-fabricated Ti6Al4 V-Cu exhibited excellent anti-inflammation and antiosteoclast capability, optimized extracellular matrix formation, and holds great potential for bone regeneration in osteoporotic patients.

Preliminary study on the corrosion resistance, antibacterial activity and cytotoxicity of selective-laser-melted Ti6Al4V-xCu alloys.

In this study, a series of Cu-bearing Ti6Al4V-xCu (x=0, 2, 4, 6wt%) alloys (shorten by Ti6Al4V, 2C, 4C, and 6C, respectively.) with antibacterial function were successfully fabricated by selective laser melting (SLM) technology with mixed spherical powders of Cu and Ti6Al4V for the first time. In order to systematically investigate the effects of Cu content on the microstructure, phase constitution, corrosion resistance, antibacterial properties and cytotoxicity of SLMed Ti6Al4V-xCu alloys, experiments including XRD, SEM-EDS, electrochemical measurements, antibacterial tests and cytotoxicity tests were conducted with comparison to SLMed Ti6Al4V alloy (Ti6Al4V). Microstructural observations revealed that Cu had completely fused into the Ti6Al4V alloy, and presented in the form of Ti2Cu phase at ambient temperature. With Cu content increase, the density of the alloy gradually decreased, and micropores were obviously found in the alloy. Electrochemical measurements showed that corrosion resistance of Cu-bearing alloys were stronger than Cu-free alloy. Antibacterial tests demonstrated that 4C and 6C alloys presented strong and stable antibacterial property against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) compared to the Ti6Al4V and 2C alloy. In addition, similar to the Ti6Al4V alloy, the Cu-bearing alloys also exerted good cytocompatibility to the Bone Marrow Stromal Cells (BMSCs) from Sprague Dawley (SD) rats. Based on those results, the preliminary study verified that it was feasible to fabricated antibacterial Ti6Al4V-xCu alloys direct by SLM processing mixed commercial Ti6Al4V and Cu powder.

Preliminary assessment of metal-porcelain bonding strength of CoCrW alloy after 3wt.% Cu addition.

In this work, a novel Cu-bearing CoCrW alloy fabricated by selective laser melting for dental application has been studied. For its successful application, the bonding strength of metal-porcelain is essential to be systematically investigated. Therefore, the aim of this study was to evaluate the metal-porcelain bonding strength of CoCrWCu alloy by three-point bending test, meanwhile the Ni-free CoCrW alloy was used as control. The oxygen content was investigated by an elemental analyzer; X-ray photoelectron spectroscopy (XPS) was used to analyze the surface chemical composition of CoCrW based alloy after preoxidation treatment; the fracture mode was investigated by X-ray energy spectrum analysis (EDS) and scanning electron microscope (SEM). Result from the oxygen content analysis showed that the content of oxygen dramatically increased after the Cu addition. And the XPS suggested that Co-oxidation, Cr2O3, CrO2, WO3, Cu2O and CuO existed on the preoxidated surface of the CoCrWCu alloy; the three-point bending test showed that the bonding strength of the CoCrWCu alloy was 43.32 MPa, which was lower than that of the CoCrW group of 47.65 MPa. However, the average metal-porcelain bonding strength is significantly higher than the minimum value in the ISO 9693 standard. Results from the SEM images and EDS indicated that the fracture mode of CoCrWCu-porcelain was mixed between cohesive and adhesive. Based on the results obtained in this study, it can be indicated that the Cu-bearing CoCrW alloy fabricated by the selective laser melting is a promising candidate for use in dental application.

Microstructure, mechanical property and metal release of As-SLM CoCrW alloy under different solution treatment conditions.

In the study, the microstructure, mechanical property and metal release behavior of selective laser melted CoCrW alloys under different solution treatment conditions were systemically investigated to assess their potential use in orthopedic implants. The effects of the solution treatment on the microstructure, mechanical properties and metal release were systematically studied by OM, SEM, XRD, tensile test, and ICP-AES, respectively. The XRD indicated that during the solution treatment the alloy underwent the transformation of γ-fcc to ε-hcp phase; the ε-hcp phase nearly dominated in the alloy when treated at 1200°C following the water quenching; the results from OM, SEM showed that the microstructural change was occurred under different solution treatments; solution at 1150°C with furnace cooling contributed to the formation of larger precipitates at the grain boundary regions, while the size and number of the precipitates was decreased as heated above 1100°C with the water quenching; moreover, the diamond-like structure was invisible at higher solution temperature over 1150°C following water quenching; compared with the furnace cooling, the alloy quenched by water showed excellent mechanical properties and low amount of metal release; as the alloy heated at 1200°C, the mechanical properties of the alloy reached their optimum combination at UTS=1113.6MPa, 0.2%YS=639.5MPa, and E%=20.1%, whilst showed the lower total quantity of metal release. It is suggested that a proper solution treatment is an efficient strategy for improving the mechanical properties and corrosion resistance of As-SLM CoCrW alloy that show acceptable tensile ductility.

Investigation on the microstructure, mechanical property and corrosion behavior of the selective laser melted CoCrW alloy for dental application.

In this study, an experimental investigation on fabricating Ni-free CoCrW alloys by selective laser melting (SLM) for dental application was conducted in terms of microstructure, hardness, mechanical property, electrochemical behavior, and metal release; and line and island scanning strategy were applied to determine whether these strategies are able to obtain expected CoCrW parts. The XRD revealed that the γ-phase and ε-phase coexisted in the as-SLM CoCrW alloys; The OM and SEM images showed that the microstructure of CoCrW alloys appeared square-like pattern with the fine cellular dendrites at the borders; tensile test suggested that the difference of mechanical properties of line- and island-formed specimens was very small; whilst the outcomes from the electrochemical and metal release tests indicated that the island-formed alloys showed slightly better corrosion resistance than line-formed ones in PBS and Hanks solutions. Considering that the mechanical properties and corrosion resistance of line-formed and island-formed specimens meet the standards of ISO 22674:2006 and EN ISO 10271, CoCrW dental alloys can be successfully fabricated by line and island scanning strategies in the SLM process.

Research on the corrosion resistance and formation of double-layer calcium phosphate coating on AZ31 obtained at varied temperatures.

In this study, the effect of varied processing temperatures on the corrosion resistance and formation of dual-layer calcium phosphate coating on AZ31 was investigated. The microstructure, phase and morphology were characterized by a scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffractometer (XRD), respectively. The in vitro degradation behavior of coated AZ31 samples were evaluated by electrochemical and immersion tests in simulated body fluid. The results showed that the varied processing temperatures responded to different microstructure, phase and morphology; and a dual-layer coating was formed during the deposition process at 70°C. Meanwhile the higher processing temperature induced a faster coating formation rate and greater surface coverage. The in vitro degradation tests in simulated body fluid indicated that the corrosion rates of AZ31 alloy were effectively decreased with increasing processing temperature, which was attributed to the denser protective coating. The formation mechanism of dual-layer coating influenced by deposition temperature was proposed.