Commercial Purity Research Articles

Mechanobactericidal Nanotopography on Nitrile Surfaces toward Antimicrobial Protective Gear.

We have much to learn from other living organisms when it comes to engineering strategies to combat bacterial infections. This study describes the fabrication of cicada wing-inspired nanotopography on commercially pure (CP) nitrile sheets and nitrile gloves for medical use using the reactive ion etching (RIE) technique. Antibacterial activity against P. aeruginosa was tested using two different surface morphologies. It was observed that the etched nitrile surfaces effectively minimized bacterial colonization by inducing membrane damage. Our findings demonstrate a single-step dry etching method for creating mechanobactericidal topographies on nitrile-based surfaces. These findings have utility in designing next-generation personal protective gear in the clinical setting and for many other important applications in the age of antimicrobial resistance.

Failure mechanism during incremental sheet forming of a commercial purity aluminum alloy

Incremental sheet forming (ISF) is known for many advantages over conventional forming, such as part flexibility, low tooling cost and higher formability. Previously various studies have explored the failure mechanism experimentally and numerically. However, limited studies have been performed on the micro-mechanics of failure during ISF process. This study involves failure mechanism during incremental sheet forming of a commercial purity aluminum alloy (AA1050). During experiments, failure (fracture) was observed in truncated cone specimens by increasing the wall angle from 71° to 72°. The mechanism behind failure was explored with detailed microstructural characterization and finite element (FE) simulations. Various samples were taken from the successfully formed and failed cones for microstructural analysis. The electron backscatter diffraction (EBSD) based microtexture measurements associate this failure with more grain fragmentation and necking or localized deformation in the failed cone. Further, the X-ray diffraction (XRD) based residual stress measurements indicate high positive (tensile) hydrostatic stresses (∼157 MPa) on the outer surface of the failed (fractured) cones. Finite element analysis (FEA) with Gurson-Tvergaard-Needleman (GTN) damage model was used for fracture prediction. The FEA results also support the residual hydrostatic stress evolution in the cones, albeit at a slightly different wall angle. Based on microstructural and finite element analysis it is concluded that deformation becomes inhomogeneous when the failure occurs during ISF process.

Effect of Bimodal Grain Structure on the Yielding Behavior of Commercial Purity Titanium Under Quasi-static Tension

Effect of Bimodal Grain Structure on the Yielding Behavior of Commercial Purity Titanium Under Quasi-static Tension

Electrochemical, Biological, and Technological Properties of Anodized Titanium for Color Coded Implants.

Anodization coloring of titanium tools or implants is one of the common methods for the differentiation of each application by its size or type. Commercial purity titanium grade 4 plates (50 × 20 × 0.1 mm) were tested to obtain their electrochemical and other technological properties. The coloring process was done using the potential of 15, 30, 45, 60, and 75 Volts for 5 s in 1 wt. % citric acid in demineralized water solution. Organic acids solutions generally produce better surface quality compared to inorganic acids. The contact angle of colored surfaces was measured by the sessile drop method. Electrochemical impedance spectroscopy and potentiodynamic polarization were used for the determination of selected electrochemical and corrosion parameters of the tested surfaces. It was found that the anodization process decreases corrosion potential significantly. It was also confirmed that a higher potential used for anodization results in higher polarization resistance but also a decrease in corrosion potential. The anodization process at 75 V produces surfaces with the lowest corrosion rate under 1 nm/year and the noblest corrosion potential. It was confirmed that the anodization process in citric acid does not affect titanium cytotoxicity.

The effect of Sr modification on the eutectic structure of AlSi7Mg alloys at different purity levels

The effect of different Sr levels on the solidification path and the microstructure of the Al-Si eutectic in AlSi7Mg alloys at 3 different levels of purity (high purity, commercial purity, and secondary alloy) was investigated. Thermal analysis technique was performed to obtain the cooling curves and characteristic temperatures of the eutectic reactions. Microstructural investigations were carried out to study the variation of the eutectic structure due to Sr addition and alloy’s purity. The results indicate how the commercially pure alloy shows the highest nucleation and growth temperatures among the unmodified alloys, while the secondary alloy has the lowest ones. Sr addition decreases the characteristic eutectic temperatures. Even though the growth temperature is similar after Sr modification in the commercial and high purity alloys, this last shows a finest eutectic structure. Different levels of Sr are required to fully modify the eutectic of the AlSi7Mg alloy at different purity grade.

ATI CP GRADE 17 TITANIUM

Abstract ATI CP Grade 17 Titanium is an unalloyed titanium grade that contains 0.04–0.08% palladium. This palladium-containing alloy extends the range of application of commercially pure (CP) titanium in hydrochloric, phosphoric, and sulfuric acid solutions. ATI CP Grade 17 Titanium is used in applications requiring excellent corrosion resistance in chemical processing or in storage applications where the media is mildly reducing or fluctuates between oxidizing and reducing. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, and joining. Filing Code: Ti-188. Producer or source: ATI.

Formation of Ultrafine Grain and Mechanical Properties in Commercial Pure Titanium Subjected to Heavy-Reduction Thermomechanical Processing Around Β Transus Temperature

Formation of Ultrafine Grain and Mechanical Properties in Commercial Pure Titanium Subjected to Heavy-Reduction Thermomechanical Processing Around Β Transus Temperature

Microstructure and corrosion resistance of commercial purity aluminum sheet manufactured by continuous casting direct rolling after ultrasonic melt pre-treatment

During the new continuous casting direct rolling (CCDR) process for manufacturing commercially pure aluminum sheet for foils, casting defects tend to arise as the raw material with huge mass flow rapidly solidifies under a high cooling rate, which generates negative effects on the formability of aluminum sheets and the performance of final foil products. Therefore, melt pre-treatment during continuous casting is very essential to improve the quality of the billet. In this study, multi-source ultrasonic field was employed to pretreat an Al melt during the continuous casting stage in a Hazelett CCDR strip production line. The Ti content distribution in the melt, the microstructure and corrosion behaviors of the rolled sheet with and without ultrasonic melt pre-treatment (UMPT) were investigated. The microstructure of the rolled sheet was refined due to the increased Ti content and uniformly distributed Al3Ti particles under UMPT. In addition, the morphology of the Fe-containing secondary phase was modified from an aggregated to a scattered structure, with reduced continuity. As a result, under the combined effects of the refined α-Al grains and secondary phase, the corrosion resistance of the rolled sheet was improved. The underlying mechanisms for the modifications of the microstructure and corrosion resistance after UMPT are also interpreted, which gives theoretical guidance on the practical applications of the ultrasound-assisted continuous casting in industrial production.

Thermal stability, grain growth kinetics, mechanical properties, and bio-corrosion resistance of pure Mg, ZK30, and ZEK300 alloys: A comparative study

Thermal stability, grain growth kinetics, tensile properties, and corrosion resistance of commercially pure (CP) magnesium can be tailored by zinc addition in conjunction with small additions of zirconium and rare earth (RE) elements, which need to be systematically investigated. Accordingly, the thermal stability, grain growth kinetics, tensile properties, and bio-corrosion resistance of hot rolled CP Mg, and ZK30 (Mg-3Zn-0.5Zr) and ZEK300 (Mg-3Zn-0.5RE-0.5Zr) alloys were compared in this work. The solute drag effect of Zn in the ZK30 alloy and the Zener pinning effect of CeZn 5 compound in the ZEK300 alloy were responsible for the improved thermal stability and higher grain growth activation energy of these alloys compared to CP Mg. The tensile properties of hot rolled ZK30 and ZEK300 alloys were superior due to their fine grain sizes. Moreover, corrosion tests in simulated body fluid (SBF) solution confirmed the higher corrosion resistance of the ZEK300 alloy for biomedical implant applications. The shear punch testing (SPT) results revealed that the ZEK300 alloy can better retain its superior mechanical properties during deformation/testing at elevated temperatures. Grain growth annealing led to a decrement in strength but an increment in the total elongations, and hence, the highest tensile toughness was obtained for the ZEK300 alloy with an average grain size of ~ 8.5 μm. Accordingly, this work proposed that RE addition at the micro-alloying level to a lean Mg-Zn alloy is quite effective in the enhancement of thermal stability, room/elevated-temperature mechanical properties, and bio-corrosion resistance.

An effective laser surface treatment method to reduce biofilm coverage of multiple bacterial species associated with medical device infection

Device associated infection (DAI) is recognized as a worldwide health challenge in total joint replacement (TJR). Bacteria exhibit very strong antibiotic tolerance when they attach to a device and form a biofilm and thus DAI is difficult to treat. In this study, a one-step, clean (no chemicals or additional materials involved) and effective surface engineering approach via laser surface treatment (LST) to tackle the DAI challenge is reported. Commercially pure (CP) Ti were laser-treated in open air using continuous wave (CW) fibre laser. The laser-treated CP Ti was tested against five bacterial species including Gram positive (Staphylococcus aureus and Staphylococcus epidermidis) and Gram negative (Pseudomonas aeruginosa, Escherichia coli and Proteus mirabilis). Live/Dead staining and image analysis results indicated that LST can significantly reduce biofilm coverage of the five tested bacterial species on the CP Ti surfaces. Overall biofilm coverage as a percentage of the surface reduced after laser treatment averaging from 4.24 % to 17.4 %. This meant that relative to the untreated surface, biofilm coverage was reduced after laser treatment, ranging from 84.9 % to 95.6 % across the five species. Furthermore, cytotoxicity results (using MTT assay) showed that the laser-treated CP Ti is non-toxic across both L929 fibroblast and RAW macrophage cell lines. Surface properties after LST were investigated using WLI and AFM (measuring micro-/nano-surface roughness and topography) as well as ToF-SIMS (measuring surface chemistry and oxide thickness), respectively. The cross-sectional microstructure at the surface was imaged using SEM and analysed by XRD, whilst the surface wettability was measured using sessile drop method. To summarise, the reduction of biofilm coverage can be attributed to the favourable changes in surface roughness and topography together with the increased concentration of oxides at the topmost surface after LST.

Statistical characterization of twin transmission across grain boundaries in magnesium

A detailed statistical analysis of twin transmission (TT) across grain boundaries is performed in rolled, commercial purity magnesium compressed along the rolling direction. EBSD images are acquired from two different cuts: a section containing the rolling (RD) and normal (ND) directions; and a section at 35° to the ND which contains transverse direction (TD). An automated twinning analysis software, METIS, is used to obtain the statistical correlations between deformation twins and other microstructural features by analyzing EBSD microstructures comprising thousands of grains and twins. This detailed statistical analysis reveals that the TT propensity is sensitive to the grain boundary (GB) misorientation angle but not to the GB misorientation axis. Specifically, TT propensity decreases with increasing GB misorientation angle; however, the decreasing trend is not monotonic. Further, the detailed analysis of TT events combining macroscopic Schmid factor and the geometric measures (m’: accounts for the alignment of both twin plane normal and shear directions; m”: accounts for the alignment of only twin shear directions; and m”’: accounts for the alignment of only twin plane normal) helps in understanding and identifying the process of twin-pair formation, i.e., co-nucleation versus transmission, also to identify the role of local stresses at GBs induced by inter-grain interaction versus twinning shear transformation processes. In addition, Bayesian inference is used to draw statistically meaningful conclusions as to the likelihood of transmission given misorientation angles. Lastly, twin chain frequency as a function of chain length is predicted using the probability distribution obtained from the Bayesian inference and compared with the actual data from the EBSD microstructures.

TIG-cladding of Al-Cu and Al-Cu-Sn alloys on pure Al substrate

A tungsten inert gas (TIG) welding process was utilized successfully to produce a dense and hard cladding layer on a commercial purity Al substrate using two commercial filler wires (L-CuP6 and L-CuSn6). Effect of the type of filler wire, welding frequency, and the type of electrical current (AC or DCEN) on the microstructure, hardness, and the residual stress of the cladding layer were studied using scanning electron microscopy, X-ray diffraction, and a hardness test. The results showed that the L-CuP6 wire produced a homogeneous layer containing Al 2 Cu-Al eutectic in an α-Al matrix. The microstructure of the cladding layer formed with the L-CuSn6 wire also contained Al 2 Cu (θ) primary intermetallic and β-Sn grains. The hardness of the cladding layer was found to depend on the fraction of Al 2 Cu intermetallic formed in the microstructure. Increasing the frequency or using a DCEN instead of AC caused the fraction of Al 2 Cu formed to decrease. These effects were attributed to the decrease in the volume of the weld pool and the inability of the DCEN to remove the oxide film from the Al substrate, respectively.

Fabrication and microstructure evolution of novel laminated TiAl composite

In this paper, we designed and prepared the novel laminated TiAl composite (LTC) consisting of alternating Ti5Si3-rich/equiaxed γ-TiAl layers (TELs) and Ti5Si3-lean/lamellar (α2/γ) layers (TLLs), which were realized by hot pressing of stacking commercial purity Ti foils and Al6Si alloy foils followed by in situ reaction annealing. The microstructure evolution and phase transformation of the laminated Ti-(AlSi) composite during different reaction annealing processes were systematically investigated by means of scanning electron microscopy, transmission electron microscope and X-ray diffraction. In addition, the formation mechanism of the LTC based on the diffusion, solution and reaction was explored in detail.

Effect of Beam Oscillation on Microstructure and Tensile Property of Electron Beam-Welded Commercially Pure (CP) Titanium

Effect of Beam Oscillation on Microstructure and Tensile Property of Electron Beam-Welded Commercially Pure (CP) Titanium

Predicting oxidation‐limited lifetime of Ni‐Al‐Cr porous radiant burners made by combustion synthesis

Ni-Al intermetallic alloys have superior high-temperature properties such as excellent oxidation resistance and high yield strength, making them particularly attractive as materials for the fabrication of porous components of energy conversion and combustion devices. In this study, the cyclic oxidation resistance of highly permeable Ni-Al-Cr alloys has been investigated. The porous alloys with a structure of irregular porous scaffold comprised of welded mm-sized spheroidal strut elements forming a net of mm-sized interconnected pore channels (porosity of 0.55–0.60, specific surface area below 10−3 m2/g) were manufactured by the combustion synthesis method using μm-sized Ni, Al, and Cr powders of commercial purity as starting reagents. The surface area of alloys exposed to oxidation was calculated with an accuracy of 6% using quantitative 2D stereology. The cyclic oxidation tests were conducted in dry artificial air at 1150 ℃ for 100 h. The Ni‐Al‐Cr alloys, compared to Ni‐Al alloys, exhibited a twofold increased oxidation resistance because of decreased scale spallation. The porous alloys were also tested in a combustion environment. The lifetime prediction showed that Ni‐Al‐Cr radiant burners could be used for > 10,000 h at a temperature of 1000 ℃, which makes them relevant for application in domestic combustion appliances such as water heating boilers.

Deformation mechanism of commercially pure titanium under biaxial loading at ambient and elevated temperatures

Commercially pure (CP) titanium is thermally processed and subjected to biaxial stress. However, the evolution of the microstructural deformation mechanisms under such circumstances is not adequately understood. In this study, the mechanical responses and microstructural deformation mechanisms of TA2 CP titanium sheets under equi-biaxial loading at room temperature (RT), 300 °C, and 400 °C were studied. The activated slip and twinning systems were investigated by transmission electron microscopy (TEM) after polished cruciform specimens were biaxially tensile-tested at RT and elevated temperatures. The results show that {112¯2} contraction twinning and {101¯2} extension twinning are the main deformation mechanisms of RT biaxial deformation, while dislocation glide is predominant in biaxial deformation at 300 °C and 400 °C. This difference yields varied work-hardening behaviors at RT and elevated temperatures. In biaxial deformation at 400 °C, the main slip trace type is multiple slip. The interaction of different slip systems in multiple slip created shear deformation concentration areas and further induced cross-slip. However, in biaxial deformation at 300 °C, the amounts of simplex and multiple slip were significantly reduced compared to those at 400 °C because the lower temperature increased the critical resolved shear stress and insufficient activated slip systems were available for grain deformation. Therefore, several stress-concentration areas were generated with the activation of cross-slip.

Corrosion behavior of novel titanium-based composite with engineering 3D artificial nacre-like structures

Metallic composites with engineering 3D bioinspired architectures are difficult to construct by traditional processing methods. Inspired by nacre structure, a novel titanium-based composite (TCCP) with engineering 3D artificial nacre-like structures consisting of commercial purity titanium (CPTi, served as brick) and Ti6Al4V (TC4, served as mud) were firstly produced by coupling selective laser melting (SLM) and hot isostatic pressing (HIP). To determine the introduction of “brick-mud” interfaces potentially whether would change the corrosion behavior of the alloy, electrochemical tests were used to express the corrosion mechanism of the TCCP. The outcomes indicated that this composite structural material also exhibits excellent corrosion resistance, which was superior to the HIP treated SLM-TC4 and close to the HIP-produced CPTi. Moreover, a continuous passive film could form on the interface between the CPTi-brick and TC4-mud region in the TCCP matrix. The study is expected to provide new insight into designing artificial nacre-like composite alloys.

Phase transformations mechanism in commercially pure titanium subjected to multiple laser shock peening

The phase transformations in commercially pure (CP) titanium subjected to multiple laser shock peening (LSP) impacts were investigated by means of scanning electron microscopy (SEM), X-ray Diffraction (XRD) and transmission electron microscopy (TEM) observations. The results showed that the LSPed samples underwent α → ω → fcc→α phase transformations as a function of the number of laser shock impacts. The α → ω phase transformation occurred during the second shock impact. The orientation relationship (OR) was {0001}ω//{11−20}α, which was consistent with the Silcock pathway. The fcc-Ti appeared after the third impact, and the content of fcc-Ti in the samples first increased and then decreased with the impact times. The α → ω → fcc phase transformations could be attributed to the input energy accumulation by multiple laser shocks, which refined the grains and formed lots of nano twins. The fcc→α reverse transformation may be related to the residual heating which is converted from laser shock energy.

Surface Free Energy and Composition Changes and Ob Cellular Response to CHX-, PVPI-, and ClO2-Treated Titanium Implant Materials.

The study evaluated the interaction of a titanium dental implant surface with three different antibacterial solutions: chlorhexidine, povidone-iodine, and chlorine dioxide. Implant surface decontamination is greatly challenging modern implant dentistry. Alongside mechanical cleaning, different antibacterial agents are widely used, though these could alter implant surface properties. Commercially pure (CP) grade 4 titanium (Ti) discs were treated with three different chemical agents (chlorhexidine 0.2% (CHX), povidone-iodine 10% (PVPI), chlorine dioxide 0.12% (ClO2)) for 5 min. Contact angle measurements, X-ray photoelectron spectroscopy (XPS) analysis, and cell culture studies were performed. Attachment and proliferation of primary human osteoblast cells were investigated via MTT (dimethylthiazol-diphenyl tetrazolium bromide), alamarBlue, LDH (lactate dehydrogenase), and fluorescent assays. Contact angle measurements showed that PVPI-treated samples (Θ = 24.9 ± 4.1) gave no difference compared with controls (Θ = 24.6 ± 5.4), while CHX (Θ = 47.2 ± 4.1) and ClO2 (Θ = 39.2 ± 9.8) treatments presented significantly higher Θ values. All samples remained in the hydrophilic region. XPS analysis revealed typical surface elements of CP grade 4 titanium (Ti, O, and C). Both MTT and alamarBlue cell viability assays showed similarity between treated and untreated control groups. The LDH test revealed no significant difference, and fluorescent staining confirmed these results. Although there was a difference in surface wettability, a high proliferation rate was observed in all treated groups. The in vitro study proved that CHX, PVPI, and ClO2 are proper candidates as dental implant decontamination agents.

The joining of CP-vanadium and Ti–6Al–4V using the Electron Beam Melting Additive Manufacturing method

The use of electron beam welding for dissimilar welding (DW) of commercially pure (CP) vanadium to Ti–6Al–4V has been investigated via ARCAM S12, an additive manufacturing powder-bed system. Investigations of bead-on-plate welds for Ti–6Al–4V were first conducted to identify the process parameters for full penetration welds with a minimum energy input of 37 mA at a traverse speed of 7 mm/s. Vanadium bead on plate welds produced a penetration of approximately 75%, which was enough to proceed onto DW experiments. Defect-free full penetration welds were produced. The DW weld zone microstructure revealed an elongated dendritic structure comprised of bulky βTi grains and a fine substructure of α' laths. Thermal imaging (TI) showed an increment in radiance temperature ahead of the melt pool, indicating that there is a minimum energy required before keyhole welding is present, confirming mathematical calculations. Mechanical characterisation finds a fair range of hardness across both base metals (BM), heat affected zones (HAZ) and fusion zones (FZ). With no yield plateau in tensile test curves, the material is confirmed to fail on the side with lower mechanical properties, i.e., vanadium, which draws a fair process window for dissimilar welding between Ti6Al4V and vanadium alloys.