Suggesting a full two level experimental factorial model with three factors to optimize Ti-HA biocomposite properties

A metal matrix composites (MMCs) is introduced to serve as synthetic bone grafts. The MMC was synthetized via powder metallurgical method after milling raw powder mixture of hydroxyapatite (HA) particles and pure titanium (Ti) powder. A full two level experimental factorial model with three factors (2^3) was developed to study the effect of three main parameters of synthetizing process on the hardness, density, and crystallite size of the composite. The synthetizing process parameters under consideration were the mechanical alloying time as well as the ceramic powder initial size and its mass fraction in the mixed powder. The results demonstrate that the composite’s hardness is increasing with higher HA mass fraction (W/W) of the composite and longer milling time. The analysis of data also show that the initial HA particle size has insignificant influence on the composite’s hardness, while higher HA content fraction in the MMC decreases the density of the composite

Studying the effect of hydroxyapatite particles in osteoconductivity of Ti-HA bioceramic

Ball milling method and powder metallurgy technology were employed to synthetize metal matrix composites (MMC) for bone grafts' applications. The raw powder of the MMC was prepared by mechanical alloying of pure titanium (Ti) powder with hydroxyapatite (HA) particles. The biocompatibilities of the sintered Ti-HA composites were examined after immersing the samples in simulated body solution (SBF) for different periods of time. SEM image and XRD results analysis were utilised to study the effect of HA on osteoconductivity of the Ti-HA composite. To this purpose, several composites were synthetized from different Ti-HA raw powder combination based on the HA particle size, milling time, and the mass fraction of HA content (% w/w) in the MMC. In-Vitro analysis of Ti-HA composite shows that composite with 30% w/w HA has higher bioactivity in comparison with composite containing pure Ti with 10% w/w HA

Effect of HAP decomposition on the corrosion behavior of Ti-HAP biocomposites

Ti-HAP biocomposites are gained attention for combining the attractive properties of Ti and hydroxyapatite (HAP). However, the decomposition of HAP at elevated processing temperatures is a major concern since it can lead to structural flaws and may deteriorate the corrosion resistance of Ti. The present study aims to investigate the corrosion behavior of Ti-HAP composite processed by powder metallurgy by performing potentiodynamic polarization and electrochemical impedance spectroscopy in 0.9wt% NaCl solution at body temperature. Results show that the presence of Ti lowers the HAP decomposition temperatures resulting in the formation of HAP-depleted zones acting as electrochemically active sites, decreasing the corrosion resistance.This study was supported by the Foundation for Science andTechnology (FCT), Portugal with the reference projects UID/EEA/04436/2013, EXCL/EMS-TEC/0460/2012, and M-ERA-NET/0001/2015, as well, by FEDER funds through the COMPETE 2020–Programa Operacional Competitividade eInternacionalização (POCI) with the reference project POCI-01-0145-FEDER-006941. The authors would also like toacknowledge Prof. Ana Senos (University of Aveiro) andProf. José Carlos Teixeira (University of Minho) for theprovision of the characterization facilities

Microwave assisted solution combustion synthesis of β-tricalcium phosphate nano-powders

A new approach for synthesis of β-tricalcium phosphate (β-TCP) was investigated by microwave-assisted combustion method. Three different fuels, glycine, urea and citric acid were used and their effects on the β-TCP powders formation were investigated. The morphology of powders, chemical and phase constituent were determined by SEM, FTIR and XRD, respectively. The results indicated that β-TCP powders with high purity could be obtained when citric acid is used as fuel; and in case of glycine and urea small amounts of hydroxyapatite (HA), calcium pyrophosphate and calcium hydrogen phosphate were detected by XRD. The morphology of β-TCP particles was found to be depended on fuel type. More uniform particle size with higher β-TCP purity was obtained by citric acid as fuel. Resumen: Se investigó un nuevo método para la síntesis del fosfato β-tricálcico (β-TCP) mediante el método de combustión asistida por microondas. Se utilizaron tres combustibles diferentes, glicina, urea y ácido cítrico, y se investigaron sus efectos sobre la formación de polvos de β-TCP. El componente químico y de fase, la morfología de los polvos fueron determinados por FTIR, XRD y SEM, respectivamente. Los resultados mostraron que se pueden obtener polvos de β-TCP de alta pureza cuando se usa ácido cítrico como combustible, y en el caso de glicina y urea se detectaron pequeñas cantidades de hidroxiapatita (HA), pirofosfato de calcio y fosfato de calcio por XRD. Se encontró que la morfología de las partículas de β-TCP dependía del tipo de combustible. El tamaño de partícula más uniforme con mayor pureza de β-TCP se obtuvo usando ácido cítrico como combustible. Keywords: β-Tricalcium phosphate, Combustion method, Fuel, Morphology, Palabras clave: β-Fosfato tricálcico, Método de combustión, Combustible, Morfologí

Dry Sliding Wear and Corrosion Performance of Mg-Sn-Ti Alloys Produced by Casting and Extrusion

The aim of the present study is to investigate the role of Ti on corrosion and the wear properties of Mg-5Sn-xTi (x = 0, 0.15, 0.75, 1.5 wt.%) alloys. The samples were fabricated by conventional casting followed by hot extrusion, and the studies were examined by means of a pin-on-disc tribometer at various loads of 6, 10, and 20 N with constant sliding velocities of 0.04 m/s at ambient temperature. The corrosion performance, using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), was studied in a basic solution containing 3.5 wt.% NaCl. The observation indicated a drop in the wear rate with an increase in Ti, while the average coefficient of friction was raised in higher Ti contents compared to the base material. The sample with 0.15 wt.% Ti exhibited superior wear properties at 6 and 10 N of normal force, while the sample with 0.75 wt.% Ti presented better wear resistance for 20 N. Electrochemical test observations demonstrated that the Ti deteriorated the corrosion features of the Mg-5Sn alloy, owing to the galvanic effects of Ti. The Mg-5Sn alloy exhibited excellent corrosion behavior (corrosion potential (Ecorr) = −1.45V and current density (Icorr) = 43.92 A/cm2). The results indicated the significant role of Ti content in modulating wear and corrosion resistance of the Mg-5Sn alloy

Effect of Ti Content on Microstructure and Mechanical Properties of Mg-Sn Alloys Produced by Casting and Hot Extrusion

Magnesium (Mg) alloys have received significant attention in various fields of applications due to their low density, high specific strength, good machinability, and damping properties. In this study, Mg95-xSn5Tix (x = 0, 0.15, 0.75, 1.5 wt.%) alloys were produced through casting and hot extrusion; the effect of Ti content was investigated on microstructure and mechanical properties using microscopical analysis, x-ray diffraction, tensile, compaction, and Vickers hardness tests. The obtained results indicated that the presence of Ti leads to sensible grain refinement and a decrease in dendrite arm spacing (DAS). Ti content of 0.15 wt.% caused a fine and homogenous distribution of Mg2Sn phases. The results showed with an increase in Ti content up to 0.75 wt.%, the lotgering factor (LF) of (002) plane decreased, indicating reduced texturing. The sample with 0.75 wt.% showed the greatest ultimate tensile strength (296 ± 6 MPa), and the sample with 1.5 wt.% Ti resulted in the highest ultimate compression strength (479 ± 13 MPa)

Geometric parameters and response surface methodology on cooling performance of vortex tubes

This research has investigated the effect of certain geometric parameters on cooling performance of three vortex tubes. The influencing parameters include three length/diameter ratios L/D = 10, 25, 40, three nozzle cases and each case with number n = 2, 4, 6 nozzles, three cold orifice/diameter ratios β = 0.389, 0.5, 0.611 and three inlet pressures Pi = 2, 2.5 and 3 bar. The experiments are conducted based on three factors, two-level and central composite face-centred design with full factorial. The results are analysed according to the principle of response surface methodology. The goodness of fit of the regression model is inspected using the analysis of variance and F-ratio test. The values of R2 and R2-adjusted are close to 100% which show a very good correlation between the observed and predicted values. The results show that the effect of number of nozzles on the energy separation depends on the L/D values